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Title: Field, Forest and Farm: Things interesting to young nature-lovers, including some matters of moment to gardeners and fruit-growers
Author: Fabre, Jean-Henri
Language: English
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FIELD, FOREST AND FARM
THINGS INTERESTING TO YOUNG NATURE-LOVERS,
INCLUDING SOME MATTERS OF MOMENT TO GARDENERS
AND FRUIT-GROWERS
BY
JEAN-HENRI FABRE
Author of “The Story-Book of Science,” “Our
Humble Helpers,” “Social Life in
the Insect World,” etc.
TRANSLATED FROM THE FRENCH
BY
FLORENCE CONSTABLE BICKNELL
NEW YORK
THE CENTURY CO.
1919
CONTENTS
CHAPTER PAGE
I The Staff of Life 3
II The History of Tobacco 11
III The Origin of Fertile Soil 16
IV Different Kinds of Soil 21
V Different Kinds of Soil (Continued) 25
VI Potash and Phosphorus 30
VII Phosphates and Nitrogen 35
VIII Vegetation and the Atmosphere 42
IX Lime 47
X Lime in Agriculture 52
XI Plaster of Paris 56
XII Plaster of Paris in Agriculture 60
XIII Natural Fertilizers—Guano 65
XIV The Stalk of the Plant 70
XV The Root 74
XVI Buds 80
XVII Adventitious Buds 84
XVIII Bulbs and Bulblets 89
XIX Tubers—Starch 93
XX Uses of Starch 98
XXI History of the Potato 102
XXII Ascending Sap 107
XXIII Descending Sap 112
XXIV Tree-Pruning 116
XXV Pinching—Bud-Nipping 120
XXVI Making Fruit Trees Bear 124
XXVII The Seed 129
XXVIII The Seed’s Food-Supply 134
XXIX Germination 138
XXX The Blossom 144
XXXI Pollen 150
XXXII The Grain of Wheat 155
XXXIII Cultivated Plants 159
XXXIV Different Ways of Propagating 165
XXXV Layering 170
XXXVI Slipping 178
XXXVII Grafting 184
XXXVIII Grafting (Continued) 190
XXXIX Grafting (Concluded) 197
XL Rotation of Crops 202
XLI Rotation of Crops (Continued) 208
XLII Land-Drainage 214
XLIII Paring and Burning 219
XLIV Wine-Making 223
XLV The Stag-Beetle 228
XLVI Sheath-Winged Insects 235
XLVII The June-Bug 242
XLVIII Caterpillars and Butterflies 249
XLIX Ants 256
L The Ant-Lion 264
LI Venomous Animals 271
LII The Phylloxera 279
LIII The Phylloxera (Continued) 288
LIV Nocturnal Birds of Prey 295
LV The Smaller Birds 300
LVI Birds’ Nests 305
LVII Migration of Birds 317
LVIII Carrier-Pigeons 322
LIX Some Prehistoric Animals 328
LX The Origin of Coal 336
LXI The Farmer’s Helpers 342
LXII The Farmer’s Helpers (Continued) 348
FIELD, FOREST AND FARM
CHAPTER I
THE STAFF OF LIFE
With his nephews as willing companions and eager listeners, Uncle Paul
continued his walks and talks in the pleasant summer afternoons.
“Bread is made of flour,” he began, “and flour is wheat reduced to
powder under the millstone. What an interesting mechanism that is, the
flour-mill, driven by water, by the wind, sometimes by steam! What
wearisome effort, what waste of time, if we had not this invention and
were forced to do its work of grinding by sheer strength of arm!
“I must tell you that in ancient times, for want of knowing how to
grind wheat, people had to content themselves with crushing it between
two stones after parching it a little over the fire. The coarse meal
thus obtained was cooked in water to a sort of porridge and eaten with
no further preparation. Bread was unknown.
“Later the plan was hit upon of kneading the meal with water and of
cooking the dough between two hot stones. Thus was obtained a crude
sort of biscuit, about as thick as your finger, stodgy and hard, and
mixed with charcoal and ashes. It was preferable to the porridge, the
insipid paste, of the earlier time, but far inferior to the poorest
bread of to-day. To make a long story short, by trial after trial
success was at last attained in the making of bread like ours. It
became necessary then, without possessing anything to compare with our
mills, to grind wheat in large quantities.
“Flour was obtained by triturating the wheat in a hollowed stone with a
pestle. This latter was sometimes light enough to be operated directly
by hand; sometimes, to produce quicker results, it was so large and
heavy that it had to be turned in its stone mortar with the help of a
long bar. Such was the first mill. With appliances of this sort I leave
you to imagine how long a time was required for the production of a
single handful of flour. For bread enough to feed one person at one
meal, wretched slaves were kept toiling from morning till night and
from night till morning in turning the pestle.”
“What cruel masters they must have had!” exclaimed Emile.
“Yes, the slaves were harnessed to the bar like beasts of burden; and
when, weakened with fatigue, they did not go fast enough, a rawhide was
applied to their bare shoulders. These unfortunate millers were poor
wretches taken in war and afterward sold in the market with the same
indifference with which a drover sells his cattle. Such, then, were the
hardships that led the way to the modern mill which to-day, with a few
turns of its water-wheel, and to the cheerful accompaniment of its
tick-tack, can make flour enough for a whole family.
“But let us leave the mill and turn our attention to the following
interesting experiment. Take a handful of flour and with a little water
make it into dough. This done, knead the dough with your fingers over a
large plate while an assistant moistens it continually with water from
a pitcher. Keep the dough well in hand and continue kneading it,
flattening it out and gathering it together again, turning it over and
over under the fine stream of water poured from above.
“Examine carefully the water that passes over the dough and washes it.
It falls into the plate as white as milk, showing that it carries with
it something from the flour. This something will finally settle at the
bottom of the liquid, and we shall find it to be a substance not unlike
the starch used for starching linen. In fact, it is starch, or fecula,
as the chemists call it—neither more nor less. The starch used in the
laundry is obtained in considerable quantities by similar means: dough
is washed and the whitened water, left undisturbed, deposits a layer of
starch which has only to be gathered together and dried. [1]
“So much, then, is made clear: flour contains starch, but it contains
something else also. There is a limit beyond which the washed dough
yields no more starch; it is useless to knead it, the water falls
colorless into the plate. What remains in one’s hands after this
prolonged washing is a soft, gluey substance, having something of the
elastic quality of rubber. Grayish in color, it has a rather pronounced
odor. When dried in the sun, it becomes hard and translucent like horn.
It is called gluten from its gluelike character, its viscosity.
“Now this substance, so unattractive in appearance, all soft and sticky
and getting clogged between the fingers—this gluten, in short—do you
know what it is? Don’t try to dispute me, for what I am going to tell
you is the exact truth. In its composition gluten does not differ from
flesh. It is vegetable flesh, capable of becoming animal flesh by the
simple process of digestion, without any material loss or gain.
Therefore it is gluten, first and foremost, that gives to bread its
great nutritive value.
“Of all the cereals wheat contains the most gluten, with rye holding
second place. Maize and rice, as well as chestnuts and potatoes, are
wholly lacking in this ingredient; and for that reason flour made from
them, rich though it be in starch, is not at all the kind of flour for
bread. This will explain to you the superiority of wheat over all other
farinaceous grains.
“Wheat, the only cereal that can give us white bread, that superior
bread which nevertheless is not always to your taste unless spread with
a little butter, does not grow in all countries. Open your atlas and
run over with your finger the countries bordering on the Mediterranean;
your travels will embrace the principal regions where wheat flourishes.
Farther north it is too cold for the successful culture of the precious
cereal; farther south it is too warm.
“But that is not all. In the privileged regions not every district is
adapted to this incomparable crop: wheat needs the mild temperature and
fertile soil of the plains, not the harsh climate and dry slopes of the
mountains. Let us consider France in particular. Its plains produce
excellent wheat, but not enough to feed the entire population;
therefore in the hilly and cooler regions, where this cereal cannot be
raised, recourse is had in the first place to rye, which yields a bread
that is compact, brown, and heavy, but on the whole preferable to any
other except, of course, wheat. This rye bread is the customary food of
the country in the greater number of our departments.
“The raising of rye becomes in its turn impossible in regions too cold
and too sterile. There then remains, as a last resort, barley, the
hardiest of cereals, which is found in the mountains until we reach the
neighborhood of perpetual snow, and can be raised even in the frigid
climate of the extreme North.
“You ought to taste the miserable bread made from barley in order to
find our bread good—or, I might better say, in order to find it an
exquisite dainty even without butter or jam. Barley bread is full of
long bristles that stick in the throat; it contains more bran than
flour; it is bitter, stodgy, and of a disagreeable odor. Oh, what sorry
stuff! And yet many have to be content with it, and are only glad if
they can get enough of it.
“In the greater part of the world wheat, widely distributed by
commerce, furnishes bread only for the tables of the rich. The rest of
the population knows nothing, as a rule, of this article of food, has
never so much as seen it, and at most has only heard of it as a rare
curiosity. In place of bread the people eat here one thing, there
another, according to the country. Asia has rice, Africa millet,
America maize. In India and China the people have hardly anything to
eat but rice boiled in water with a little salt. Half the entire world
has practically the same diet.
“The plant that produces rice has a stalk resembling that of wheat, but
instead of ending in an upright ear it bears a cluster of feeble and
pendent branches, all loaded with seeds. The leaves are narrow and
ribbon-shaped, rough to the touch. This plant is aquatic. In order to
flourish, it must send down its roots into the submerged mud and spread
its foliage, excepting the tip, in the flood. Marshy shallows,
inundated a part of the year, are adapted to its cultivation.”
“But what do they do where there are no such marshes?” asked Louis.
“When such marshes are lacking, the ingenious Chinaman floods the
lowlands with water from some near-by stream until the ground is all
soft and muddy. He then draws off the water through a series of little
canals, and works the mud with a light plow drawn by a buffalo, a kind
of ox with a long beard hanging from its chin and a mane waving on its
back.
“The seed once sown in the furrows and the young plants started, the
water from the stream is again made to flood the fields, where it
remains until harvest time. Then for the second time it is drawn off,
and the reaper, sickle in hand and with the black mud up to his knees,
cuts down the rice-laden tops of the stalks.
“Maize, or Indian corn, is the staple food of South America, as rice is
that of Asia. Many call it Turkish wheat, a name doubly inappropriate,
for in the first place this grain is not indigenous to Turkey, but to
America, and in the second place it has nothing in common with the
wheat from which bread is made. From America its cultivation has spread
to our part of the globe.
“The ear of maize is very large and is composed of full, rounded
kernels, yellow and shiny, closely packed in regular rows. Like rice,
maize furnishes a fine flour of pleasing appearance but lacking in one
essential: it contains no gluten. Hence the utter impossibility of
using either rice or maize for making bread, despite the good
appearance of the flour made from them.
“Nevertheless maize is a very wholesome article of food, and one of
great value in the country, where the appetite is sharpened by open air
and hard work. Only it is not in the form of bread that it best yields
its nourishment, but rather in that of porridge, or boiled meal and
water.”
CHAPTER II
THE HISTORY OF TOBACCO
“Before taking the form of the powder which the user of snuff pushes up
into his nose to tickle his nostrils and promote sneezing, before being
rolled into the cigar or reduced to that crisp, moss-like substance
which the smoker stuffs into his pipe, tobacco has had a previous
existence as a plant bearing this same name. A stalk about one meter in
height, large, clammy leaves of a strong odor, bright red flowers each
shaped like a narrow funnel and expanding into the five points of a
star at the orifice, dry capsules filled with innumerable little
seeds—there you have the tobacco plant.
“Only the leaves are used, and these only after undergoing certain
processes that intensify their natural properties and cause them to
lose their green color. Rolled into compact little cylinders, they
become cigars; cut very fine, they take the form of smoking tobacco.
Reduced to powder, they furnish what is known as snuff.
“America, the same land to which we owe the potato, also gave us
tobacco. When, almost four centuries ago, Christopher Columbus
discovered the new world, one of the first landings he made was on the
large island of Cuba. Apprehensive of danger in the forests from the
savage tribes on every side, Columbus sent scouts ahead to reconnoitre
the country.
“The sailors forming this party encountered on the way, to their
extreme surprise, numerous Indians, both men and women, holding each a
sort of lighted fire-brand between the teeth and inhaling the smoke.
These fire-brands, called ‘tabagos,’ were made of a plant rolled up in
a dry leaf. There, then, were the first smokers and the first cigars
recorded in history.
“The natives of Cuba and the neighboring islands had, we infer, been
addicted to smoking for a long time, probably for centuries, when the
Europeans first appeared among them. They had their rolls of dry
leaves, or tabagos, and their smoking appliances of soft stone or baked
clay, appliances called by us ‘pipes’ and by them ‘calumets.’ Tobacco,
in fact, played a prominent part in their medicine, their superstitious
observances, and their political assemblies.
“Consulted as to future events, the soothsayer first of all inhaled the
smoke of several tabagos, while the other persons present, seated in a
circle, vied with one another in the energy of their smoking, their
ultimate object being to enwrap themselves in a dense cloud. Then from
the midst of this cloud the soothsayer, his imagination wrought to a
high pitch by the fumes of the tobacco, delivered his oracles in
unwonted terms that made the hearers believe they were listening to the
voice of God.
“A like ceremony was observed in the assemblies held for discussing
public affairs. Seated on a stone and inhaling the smoke from his
calumet, the orator who was about to take the floor waited in passive
silence while the chiefs of the nation approached him, one at a time,
to blow into his face plenteous puffs from their pipes and to commend
to him the interests of the tribe. These fumigations concluded, the
orator abandoned himself to his eloquence amid the enthusiastic acclaim
of the assembly.
“Seeing the islanders smoking, Columbus’s companions wished to try this
singular custom for themselves. To the gratification of this desire the
Indian lent his ready assistance: he showed them how the tabago is
rolled, and how the calumet is filled and lighted. Though history is
silent on the subject, it is clear that the first sailor to undertake
the inhalation must have been seized with that fearful nausea which no
novice in smoking can escape. A stomach of any delicacy would have been
forever repelled; the harsh gullet of the mariner found a certain charm
in the thing when once the trying experiences of initiation were over.
“The taste for smoking was so soon acquired that, on their return to
Spain, the companions of Columbus very quickly extended this Indian
custom in their own country. Before long, too, there was discovered a
new way to use tobacco: some one conceived the idea of reducing the
leaf to a dry powder and stuffing it into the nostrils, sniffing with
each pinch of the powdered substance. The Indian had discovered smoking
tobacco; the European in his turn invented snuff.
“Spain and Portugal numbered their smokers and snuff-takers by the
thousand when, in 1560, tobacco made its first appearance in France.
Nicot, French ambassador at Lisbon, sent as an object of curiosity to
his sovereign queen, Catherine de Médicis, some seeds of the
fashionable plant and a box of tobacco in powdered form. Charmed with
this gift, the queen quickly contracted the habit of taking snuff. To
please her, tobacco was cultivated, and snuff-takers soon became
numerous in all the provinces. It was said that a certain great
personage of the period took as much as three ounces daily. He
certainly must have had his nose well tanned.
“From one nation to another the use of tobacco gradually spread, but
not without serious opposition. The Turks are to-day passionately
addicted to smoking, extremely fond of their long pipes; yet hear what
sort of a reception they at first gave to tobacco. Against smokers and
snuff-takers their emperor, Amurat, issued an edict severe to the point
of cruelty. Every delinquent was condemned to receive fifty strokes
with the rod on the soles of his feet.”
“That ought to have driven tobacco out of the country in short order,”
remarked Jules.
“That was merely a warning to first offenders,” returned his uncle.
“For a second offense the luckless person caught in the act had his
nose cut off. It was a radical measure to discourage the snuff-taker:
no more nose, no more snuff. But the smokers, after this horrible
mutilation, persisted in their smoking.
“A king of Persia devised what he thought would cure even this habit:
every one caught with a pipe in his mouth had his upper lip cut off. At
the same time, of course, every nose proved guilty of snuff-taking fell
under the executioner’s knife. But the atrocious edict of the Persian
king proved as futile as that of the Turkish emperor. Despite all the
noses struck off, all the lips cut away, all the feet made to tingle
under the rod, the use of tobacco still continued to spread. These
fruitless severities had to be abandoned.
“Other regulations sprang up here and there, less cruel, but
sufficiently fruitful in fines, imprisonments, vexations of all sorts.
Still nothing was of any avail; smokers and snuff-takers remained
incorrigible. Finally, taking wiser counsel, the government authorities
conceived a plan for making this passion, which no severity had been
able to subdue, yield them large revenues. The government itself became
exclusive vender of the very article it had at first proscribed with
such rigor. France alone derives a yearly revenue of almost three
hundred million francs from the sale of tobacco.”
CHAPTER III
THE ORIGIN OF FERTILE SOIL
“Fertile or arable soil,” resumed Uncle Paul, “constitutes only the
surface layer of earth, that which is worked by the farmer’s implements
and yields nutriment to the roots of plants and promotes their
development. In one place you will see bare rocks and utter barrenness;
in another you find fertile soil to a depth of an inch or two, scantily
carpeted with grass; and again, in a third, you come upon rich earth so
deep as to maintain abundant vegetation. But nowhere does this fertile
layer have an indefinite thickness: at a depth never very considerable
a subsoil having the qualities of the neighboring mountains is sure to
be found. How then has there come to be formed this layer of earth
whence is derived all the nutriment required by plants, animals, and
men?
“Undermined all winter, and even the whole year round on high
mountains, by the ice that forms in their slightest fissures, rocks of
all kinds break into small fragments, divide into grains of sand, fall
into dust, and furnish the powdery mineral matter which the rain washes
away and deposits in the valleys. This as a rule is the origin of
broken stones, sand, clay, and fertile soil. Ice by its expansive force
has detached them from the tops of mountains and the waters have swept
them away and carried them further. One can form an idea of the action
of ice in crumbling rocks to make soil of them and enrich the valleys,
by examining the surface of a hard road at the moment of thawing.
Firm underfoot before freezing, this surface loses its firmness after a
thaw and is pushed up here and there in little finely-powdered clods.
At the moment of freezing, the humidity with which the soil was
impregnated turned into ice which, increasing in volume, reduced to
fine particles the surface layer of the road. When the thaw comes,
these particles which the ice no longer holds together form first mud,
then dust. In exactly this manner arable land was formed by the
disintegration of rocks of all kinds, which were reduced to particles
by the action of frost.
But soil suitable for agriculture contains not only powdery mineral
matter, but also a little mold from the decomposition of vegetable
matter. To give you an idea of the causes which from the very earliest
times have little by little fertilized this rock-dust with vegetable
mold, let us take the following example.
Geography has taught you what a volcano is. It is a mountain whose
summit is hollowed out in an immense funnel-shaped excavation called a
crater. From time to time the ground trembles near a volcano and
formidable noises similar to the rolling of thunder and the booming of
cannon are heard from the depths of the mountain. The crater throws up
into the air a lofty column of smoke, dark by day, fiery red at night.
All at once the mountain is rent and vomits up through the crevices a
stream of fire, a current of melted rock, or lava. Finally the volcano
quiets down; the source of the terrible flood dries up. The streams of
lava harden and cease running; and after a lapse of time which may be
years they become quite cold. Now what is to become of this enormous
bed of black stone similar in character to the slag from a forge? What
will this sheet of lava covering an area of several square miles
produce?
“This desolate, blasted expanse seems destined never to be clothed with
verdure. But in any such assumption one would be mistaken. After
centuries and centuries a vigorous growth of oaks, beeches, and other
large trees will have taken root there. In fact, you will see that air,
rain, snow, and, above all, frost attack in turn the hard surface of
the lava, detach fine particles from it, and slowly produce a little
dust at its expense. On this dust there will spring into being certain
strange and hardy plants, those white or yellow patches, those
vegetable incrustations, calculated to live on the surface of stone and
known as lichens. These lichens fasten themselves to the lava, gnaw it
still more, and in dying leave a little mold formed from their decaying
remains. On this precious mold, lodged in some cavity of the lava,
there is now a growth of mosses which perish in their turn and increase
the quantity of fertilizing material. Next come ferns, which require a
richer soil, and after that a few tufts of grass; then some brambles,
some meager shrubs; and thus with each succeeding year the fertile soil
is added to from the new remnants of lava and mold left by the
preceding generation of plants that have gone to decay. It is in this
way that gradually a lava-bed finally becomes covered with a forest.
“Our own arable land had a similar origin. Sterile rocks, hard as they
are, contributed the mineral part by being reduced to dust through the
combined action of water, air, and frost; and the successive
generations of plant-life, beginning with the simplest, furnished the
mold.
“Notice how admirably, in the processes of nature, the smallest of
created beings perform their part and contribute as best they can to
the general harmony. To produce fertile soil there is needed something
more than the frosts and thaws that crumble the hardest rock: there is
need of plants hardy enough to live on this sterile soil, such as tough
grasses, mosses, lichens, which gnaw the stone. It is through the
medium of these rudimentary plants, so pitiful in appearance and yet so
hardy, that the dust of the rocks is enriched with mold and converted
into a soil capable of bearing other and more delicate plants.
“It is not in cultivated fields that you will find those thick carpets
of mosses and lichens, valiant disintegrators of stone; it is on the
mountain-tops that they can be seen at their work of crusting over the
smooth rock in order to convert it into fertile soil. It is from these
heights that this fertile soil has descended, little by little, washed
down by the rain, until it has fertilized the valleys. This work is
going on all the time; in hilly regions plants of the lowest order are
constantly adding to the extent of arable land. The little threads of
rain-water that furrow these regions carry away with them some of this
humus and bear it to the plains below.
“What a worthy subject for our thoughtful study is this formation of
arable soil by these legions of inferior plants, obscure workers
indefatigably crumbling the rock! What immense results obtained by the
simplest means!”
CHAPTER IV
DIFFERENT KINDS OF SOIL
“Four substances, mingled in very variable proportions, enter into the
composition of fertile soil, or arable land, namely: sand or silica,
clay, limestone, and humus, or vegetable mold. Each one of these
ingredients separately would make but very poor soil, quite unsuited
for agriculture; but united, mixed together, they fulfill the
conditions necessary to fertility. Arable land generally contains all
four, with the predominance sometimes of one, sometimes of another. The
soil takes the name of its most abundant constituent. Thus have arisen
the names, silicious soil, argillaceous soil, calcareous soil, and
humous soil, to designate the fertile lands dominated respectively by
sand, clay, limestone, and humus. Compound terms are also used. For
example, when it is said of a certain soil that it is
argillo-calcareous, it is meant that clay and limestone are its chief
constituents.
“Sand consists of particles, more or less minute, of very hard rock,
sometimes opaque, sometimes as transparent as glass, and always easily
recognizable by its property of emitting sparks when struck with steel.
Flint and white pebbles belong to this kind of rock, which is called
silex, silica, or quartz. These three expressions mean about the same.
Sandy soils have little consistency, are easily permeated by water, and
freely absorb the sun’s heat, which makes them very subject to drought.
“The name of granite is given to a rock composed chiefly of silica and
which forms whole mountains, as in central France and in Brittany. The
soil formed by the gradual disintegration of this rock is sometimes
called granite soil. It is not very good for agriculture. Chestnut
trees prosper in it, as well as certain wild plants characteristic of
this kind of land. The principal ones are the various species of
heather and the purple digitalis. Heather, with its dainty little pink
blossoms, carpets in richest abundance the poorest of sandy soils. The
purple digitalis is a large-leaved plant whose flowers, red on the
outside, striped with purple and white inside, are arranged in a long
and magnificent distaff reaching almost to the height of a man. The
flowers are in the shape of long tun-bellied bells or, rather,
glove-fingers; hence the plant is sometimes called foxglove, sometimes
lady’s fingers.
“The soil composed of substances thrown up by volcanoes is also sandy,
and is called volcanic soil. It is generally black and sometimes very
fertile.
“Sandy-clay soil is found in the valleys of great rivers. It is the
most fruitful and the easiest to cultivate. Such are the soils of the
Rhone valley, the valley of the Loire, and that of the Seine. It is
still more fertile if it is flooded by the stream at high water. Then
the river deposits a rich slime composed of clay and organic matter
washed down by the current.
“The soil of heathy or shrubby land is composed of fine sand and of
humus from the decayed leaves of heather and other plants. It is only
used for flower gardens, and furnishes an example of what might be
called sand-and-humus soil.
“Clay is a soil which, when moistened with water and thoroughly
kneaded, becomes a soft and tenacious dough, suitable for molding into
any desired shape. When perfectly pure it is white, and is known as
kaolin, a rare substance of which porcelain is made. Plastic clays are
those that are unctuous to the touch, forming with water a yielding
mass that hardens with firing. They are used in making pottery.
Smectite, or fuller’s earth, is a clay of very different character, not
pliable when moistened, but very absorbent of grease and hence used by
fullers for cleansing cloth of the oil left on it in weaving. Ochres
are clays colored either red or yellow by iron-rust. They are used in
coarse painting. Red chalk belongs to this class of clays. Marl is a
mixture in variable proportions of clay and limestone. According to
which constituent predominates, it is called argillaceous or
calcareous. Subjected to the action of air and moisture, marl becomes
flaky and crumbles to dust. Marl is used in agriculture to improve the
soil.
“A clay soil is quite the opposite of a sandy soil: water makes it
swell and converts it into a sticky paste which clings tenaciously to
farming implements. Once wet, it is cold, that is to say it dries very
slowly. A spade can only divide it into dense clods slow to crumble in
the air and not fit for receiving seed. The farmer must be careful to
drain off the water and break up the ground by working it before and
during frosts. It is improved by mixing with it sand, coal-ashes, and
lime. Wheat flourishes better in a clayey soil than in any other kind.
“Clayey soils are recognized by their vegetation. The wild plants
peculiar to this kind of soil are colt’s-foot and danewort. Colt’s-foot
is also called horse-foot from the shape of its leaves, the outline of
which reminds one of a horse’s hoof. The leaves are white underneath.
The flowers are yellow like little marigolds, and they appear at the
beginning of spring before the leaves. Danewort is a kind of herbaceous
elder of about half the height of a man. Its small white flowers are
succeeded by berries full of a violet-red juice.”
CHAPTER V
DIFFERENT KINDS OF SOIL
(Continued)
“Limestone is the rock from which lime is obtained. It is composed of
carbonic acid and lime. To obtain the latter, the limestone is
subjected to intense heat in a furnace or lime-kiln. The carbonic acid
escapes, is dissipated in the air, and only the lime remains. In arable
land limestone is found rather often in smaller or larger pieces, but
more frequently as a fine powder which the eye can scarcely distinguish
from the other constituents, especially clay. The water of rivers and
other streams almost always contains a small proportion of dissolved
limestone. Thence comes the thin layer of stone that accumulates little
by little on the inner surface of bottles, coating the glass. Some
waters contain enough of this dissolved limestone to deposit a mineral
crust on objects immersed in them, as mosses and aquatic plants, and to
obstruct their aqueducts. The clearest water, in which no foreign
substance can be seen, absolutely none, nevertheless contains dissolved
limestone, just as sweetened water contains invisible sugar. In
drinking a glass of water we drink a little stone at the same time. Our
body, in order to grow strong and increase in size, needs considerable
calcareous matter for the formation of bones, which are to us what its
solid framework is to a building. This material, so necessary to us, is
not created by us; we obtain it from our food and drink. Water plays
its part in furnishing this limestone, which it furnishes also to
plants; they all contain a greater or less proportion of this mineral
matter.
“Calcareous soils are whitish from their chief constituent, chalk.
Entirely sterile when the proportion of limestone is excessive, they
are tolerably productive when clay is added. They are especially
suitable for vineyards and for raising lucerne, sainfoin, and clover.
Champagne and the south of France offer examples of this kind of soil.
Its principal varieties are chalky soil, which is nearly sterile,
containing as much as ninety-five per cent of chalk, and marly soil
which is composed of clay and chalk.
“The plant-life characteristic of calcareous soils comprises the
box-tree, whose compact and fine-grained wood is so esteemed by
turners; the wild cornel, whose red, olive-shaped fruit is one of the
best-liked autumn products that nature offers us; and the alkekengi, or
winter cherry, whose yellow berries are used for coloring butter. These
berries are encased in a large, gorgeously red membranous bag.
“Wood, leaves, herbage, left a long time in contact with air and
moisture, undergo a slow combustion; in other words, they rot. The
result of this decomposition is a brown substance called humus or
vegetable mold. The heart of old hollow willows is converted into
humus; it is the same with leaves that fall from the trees and rot on
the ground. Humus from the remains of earlier generations of plant-life
nourishes the plant-life of to-day, and this in turn will become mold
from which future plants will spring. It is in this way that vegetation
is maintained in places not cultivated by man. Humus, then, is nature’s
manure. Where it is allowed to form freely, vegetation never loses its
vigor, using over and over again the same material, which takes
alternately the two forms of plant and humus. But hay from the field is
stored in the hay-loft, and the annual harvest of wheat is taken to the
granary. Thus the land is robbed of the mold that would be formed
naturally by the rotting of this hay and wheat; therefore we must give
back to it, under some form or other, this mold that has been taken
away, since otherwise the soil will become less and less productive
until finally it is quite sterile. This restitution is made in the form
of animal manure, which is a sort of humus produced by digestive
processes instead of by natural decay.
“Humus plays a twofold part in the soil. First, it mellows the land, or
in other words makes it more easily permeable by air and water.
Secondly, by the slow combustion taking place in the humus there is
constantly being liberated a small quantity of carbonic acid gas, which
is taken up by the adjacent roots. Agriculture can succeed only in so
far as the soil contains humus. Wheat requires nearly eight per cent,
oats and rye only two per cent. In poor, sandy soils, to increase the
amount of vegetable mold, it is customary to plow certain green crops
under, as the farmers express it; that is, the surface soil is turned
over and the growing crop intended for manuring purposes is buried and
left to decay in the ground. That is what is done when the plowman
turns under a field of growing grass or a stretch of clover. When it is
proposed to improve a piece of land by this process, it is the practice
to begin by raising a crop (which will later be turned under) that
derives the greater part of its nourishment from the air, since the
soil in this instance cannot of itself furnish this nourishment. Among
the plants satisfying these conditions are buckwheat, clover, lupine,
beans, vetches, lucerne, and sainfoin.
“Soils rich in humus have for their chief constituent the brown
substance that results from the decaying of leaves and other vegetable
matter. Turf land stands first as rich in humus. Turf is a dark, spongy
substance that forms in moist lowlands from the accumulation of
vegetable refuse, especially mosses. Turf, or peat, as it is also
called, is used for fuel. To turn such a soil to account, it must first
be made wholesome by drainage, it must be mellowed by paring and
burning and by the addition of sand and marl, and a proportion of lime
must be mixed in to hasten the decomposition of all vegetable matter.
Turf lands are recognized by their sphagnei, great mosses that grow
with their roots in the water; and by their flax-like sedges, from the
tops of which hang beautiful tufts of down having the softness and
whiteness of the finest silk.”
CHAPTER VI
POTASH AND PHOSPHORUS
“Let us burn a plant, no matter what kind. The first effect of the heat
is to produce carbon, which, mixed with other substances, constituted
the plant. If combustion continues, this carbon is dissipated in the
air in the form of carbonic acid gas, and there remains an earthy
residue which we call ashes. Here then are two kinds of material,
carbon and ashes, which without exception enter into all plant-life.
The plant did not create them, did not make them out of nothing, since
it is impossible to obtain something from nothing. It must, then, have
derived them from some source. We shall take up before long the subject
of coal and its origin, and shall find that it comes chiefly from the
atmosphere, whence the leaves obtain carbonic acid gas, which they
decompose under the action of the sun’s rays, retaining the carbon and
throwing off the air in a condition fit for breathing. The vegetation
of the entire earth thus finds its principal nutriment in the
atmosphere, an inexhaustible and increasingly abundant reservoir,
because the respiration of animals, putrefaction, and combustion are
continually giving forth as much carbonic acid gas as the combined
plant-life of the earth can consume. To maintain the fertility of his
fields, therefore, the farmer need not give a thought to the subject of
carbon; with no assistance from him his growing crops find in the air
all the carbonic acid gas they require. There remains for our
consideration, then, the residue left after combustion, the ashes in
fact, a mixture of various substances of which we will now examine the
most important.
“Let us put a few handfuls of ashes to boil in a pot of water. After
boiling a little while we will let the contents cool. The ashes settle
to the bottom and the liquid at the top becomes clear. Well, we shall
find this liquid emitting a peculiar odor, exactly like that which
comes from the lye obtained by passing water through a barrel of ashes.
We shall also find that it has an acrid, almost burning taste. This
smell of lye, this acrid taste were not in the water at first; they
come from the ashes, which have yielded a certain constituent to the
water.
“Hence we see that ashes must contain at least two substances of
different kinds, of which the principal one cannot dissolve in water,
but settles at the bottom as an earthy deposit, while the other,
forming but a very small part of the whole, dissolves easily in water
and gives it its properties, especially its odor and its acrid taste.
“If we wish to obtain this latter element by itself, we can very easily
do so. All that is necessary is to put the clear liquid into a pot over
the fire and boil it until all the water has evaporated. There will be
left a very small quantity of whitish matter resembling table salt. But
despite its appearance it is not table salt by any means; far from it,
as we shall quickly discover from its unbearable taste. It is known as
potash, and it is what makes lye so good for cleaning linen.
Furthermore, of the various components of ashes it is the one most
essential to vegetation. Every tree, every shrub, every plant, even to
the smallest blade of grass, contains a certain proportion of it,
sometimes larger, sometimes smaller, according to the kind of
plant-life, and therefore must find it in the soil in order to thrive.
Let us add that in growing plants potash is not as the action of fire
leaves it after the plants have been reduced to ashes. In nature it is
combined with other substances which free it from that burning
acridity. In the same way carbon, when combined with other elements,
loses its blackness and hardness; in fact, it is no longer common coal.
“What else is there in ashes? A short account of the matter will tell
us. In 1669 there lived in Hamburg, Germany, a learned old man named
Brandt, whose head was a little turned and who sought to turn common
metals into gold. From old iron, rusty nails, and worn-out kettles, he
hoped to produce the precious metal. But he did not succeed in his
endeavors, nor was it destined that he should succeed, for the simple
reason that the thing is impossible. Never is one metal changed into
another. When he was about at the end of his resources he took it into
his head to conceive a crowning absurdity. He imagined that in urine
would be found the ingredient capable of turning all metals into gold.
Behold him, then, boiling urine, evaporating it, and cooking the
disgusting sediment, first with this, then with that, until at last one
evening he saw something shining in his phials. It was not gold, but
something more useful: it was phosphorus, which to-day gives us fire.
Don’t make fun of old Brandt and his foolish cooking: in seeking the
impossible he made one of the most important discoveries. To him we owe
the sulphur match, that precious source of light and fire so easily and
quickly used.
“If you examine a sulphur match you will see that the inflammable tip
contains two substances: sulphur, laid on to the wood, and another
substance added to the sulphur. This last is phosphorus, colored with a
blue, red, or brown powder, according to the caprice of the
manufacturer. Phosphorus by itself is slightly yellow in color and
translucent like wax. Its name means ‘light-bearer.’ When rubbed gently
between the fingers in the dark, it does indeed give out a pale gleam.
At the same time there is a smell of garlic; it is the odor of
phosphorus. This substance is excessively inflammable: with very little
heat or with slight friction against a hard surface, it catches fire.
Hence its use in the manufacture of matches.
“Phosphorus is a horribly poisonous substance. By melting a little of
it in grease a poison can be obtained that will destroy rats and mice.
Crusts of bread are smeared with this composition and exposed in places
frequented by these animals. A nibble is enough to ensure speedy death.
Hence you perceive that because of their poisonous nature matches are
to be handled with extreme care. Contact with food might produce the
gravest consequences.”
CHAPTER VII
PHOSPHATES AND NITROGEN
“Phosphorus, which is a dangerous poison, as we have seen, is
nevertheless found in abundance in the bodies of all animals. It occurs
in the urine, whence Brandt was the first to extract it; it is found
still more plentifully in the bones, and from thence it is now
obtained. There is some in meat, in milk, and in cheese; also in
plants, notably cereals; hence flour and bread contain it. But do not
be alarmed: we shall not die of poison like the rats that have nibbled
crusts smeared with grease and phosphorus.”
“But why not,” asked Emile, “if we eat it as the rats do?”
“I will try to explain,” replied his uncle. “When two or more
substances are mixed together, they lose their original properties,
while the new substance obtained by their combination is found to
possess new properties having nothing in common with the old ones. Thus
carbon, when combined with the air that we breathe, becomes an
invisible gas, subtle, and unfit for breathing. In like manner lime,
burning to the taste, is converted by union with carbonic acid gas into
chalk, a calcareous stone void of taste. Furthermore, poisonous
substances, deadly in a very small dose, may become harmless and even
enter into the composition of our food when they are combined with
other substances. Thus it is with phosphorus. What, then, is united
with phosphorus in the form in which it ceases to be poisonous and
enters into the composition of meat and flour? That is what we will now
consider.
“When phosphorus is burned it produces a thick white smoke, of which
you can get some idea by striking a number of matches all at once. This
white smoke with the slightest trace of humidity is reducible to an
extraordinarily acid liquid called phosphoric acid. Since this compound
results from the combustion of phosphorus, just as carbonic acid is the
result of the combustion of carbon, it must and in fact does contain
the air without which no combustion can take place. Phosphoric acid is
no longer inflammable, however much it may be heated; being itself the
product of combustion, it cannot burn again. But if there is no danger
of its catching fire, phosphoric acid is nevertheless dangerous on
account of its intense acidity, which makes it violently corrosive in
its action on flesh. If mixed with lime, however, this formidable
compound loses its injurious properties and is changed into a white
substance without the least taste or the slightest poisonous effect.
This substance is called phosphate of lime. Burnt phosphorus and lime,
thus united, furnish the greater part of the mineral matter found in
bones. Put a bone into the fire: the grease and juices that permeate
its substance will be burnt up and the bone will lose a part of its
weight and become friable and perfectly white. Well, this bone,
calcined in the fire for a long time, is composed chiefly of phosphate
of lime. It contains phosphorus, the most combustible of substances,
and yet is itself absolutely incombustible; it contains one of the most
poisonous substances, and yet is itself quite harmless; into its
composition there has entered an ingredient possessing atrocious
acidity, and yet the compound itself has no taste. Similarly combined
and equally harmless, phosphorus is found in meat, milk, cereals, in
flour and bread.
“A cow can furnish each week about 70 liters of milk containing 460
grams of phosphate. This phosphate comes from hay, which obtains it
from the soil. But as the soil contains only a moderate quantity of it,
and the hay continually takes it away, the supply will at last become
exhausted and the milk will become poorer and less abundant. If a
kilogram of powdered bones, containing about the same quantity of
phosphate as the 70 liters of milk, is spread over the pasture, it will
make good the weekly loss in phosphate that the soil undergoes in the
production of the cow’s milk. Hence the efficacy of powdered bones on
exhausted pasture land.
“Phosphoric acid combined with other substances is found in all our
agricultural products, and hence the phosphate from bones has a very
marked effect on our crops. Harvests have been doubled as if by magic
through the use of powdered bones. A kilogram of this powder contains
enough phosphoric acid for the growth of a hundred kilograms of wheat.
Despite their great value as a fertilizer bones will never be thus used
except to a limited extent, because they are not abundant enough and
also because they are much in demand in various arts and manufactures.
Fortunately in some localities phosphate of lime is found in certain
coarse pebbles called nodules or coprolites. These precious stones are
carefully collected and ground to powder in a mill. Then, in order to
make the substance more soluble in damp soil, and thus better fitted
for the nutrition of plants, it is sprayed with an extremely corrosive
liquid called sulphuric acid or, more commonly, oil of vitriol. In this
way is obtained the superphosphate of lime which manufacture gives to
agriculture as one of the most powerful of fertilizers, especially for
the raising of grain.
“We were wondering a little while ago what substances could be
contained in the ashes of a burnt plant, and we have now found potash
to be one of them. Moreover, since all vegetation must have phosphate
in order to thrive, this also ought to be found in the ashes, phosphate
being indestructible by heat. And, in fact, after the incineration of
any vegetable matter whatever, as a bundle of hay or a handful of
grain, the delicate processes of science can always recover this
compound of phosphorus; and they further find lime, iron in the form of
rust, the silicious component of pebbles, and divers other substances
of less interest.
“To finish this difficult but very important subject of the nutrition
of plants, I must say a few words about ammonia. This word does not
tell you anything since it is a new word to you. But I will make its
meaning clear to you by a familiar illustration.
“You must have noticed the strong, penetrating odor prevalent in
ill-kept water-closets; and you have also perceived the same odor when
soiled garments are cleaned with a certain liquid that looks like clear
water. Well, this odor, so pungent that it almost produces the effect
of fine needles thrust up into the nostrils and brings tears to the
eyes, is the odor of ammonia.
“Ammonia is an invisible gas capable of being taken up in large
quantities by water, the mixture being known as aqua ammoniæ, or water
of ammonia. Combined with other substances ammonia loses its pungent
odor and forms compounds which are among the most effective
fertilizers. These compounds furnish vegetation with one of its
essential ingredients called nitrogen. By itself nitrogen is an
odorless and colorless gas. In this state it forms four-fifths of the
volume of ordinary air, the air we breathe. The other fifth is composed
of a second gas called oxygen, also colorless and odorless. It is
oxygen that our lungs demand when we breathe, and it is oxygen that is
necessary when we wish to burn anything. It is this alone that plays
its invaluable part in the combustion of certain substances in our
blood and in the generation of natural heat; it is this that in the
process of combustion releases carbon, phosphorus, sulphur, and other
combustibles, to combine with them and produce a compound known as
carbonic acid gas in the case of burnt carbon, phosphoric acid in the
case of phosphorus. In fact, to it belong the properties that we have
until now attributed to the atmosphere as a whole. As for nitrogen, it
has no other purpose in the atmosphere than to moderate by its presence
the too violent energies of oxygen; it plays there the part of the
water that we put into too strong wine.
“All vegetation requires nitrogen. Wheat, for example, must have it to
develop the grain in the ear; peas, beans, lentils demand it in order
to fill out their pods; the pasture and the hay-field need it if they
are to furnish the nutriment that the sheep and the cow will transform
into milk. But plants cannot take this nitrogen from the air, where it
is so abundant; it must be served up to them after a certain necessary
preparation. We ourselves need phosphorus, since it enters into the
composition of our bones; we need carbon still more, the principal fuel
used in maintaining the heat of the body. But are we to eat the
charcoal that the charcoal-burner manufactures in his furnace, and the
phosphorus used in the making of matches? Certainly not. The first
would be a frightful mouthful, the second an atrocious poison. We must
have them prepared in a suitable way, such as they are found in bread,
milk, meat, fruits, vegetables. In the same manner plant-life requires
nitrogen, not as it occurs in the atmosphere, but as it exists in
certain combinations, of which the most notable are the compounds of
ammonia. This explains to us the highly beneficial effect of manure on
our crops. Manure is composed of the bedding used in stables and the
animal excrement with which it has become mixed and impregnated. Now
this excrementitious matter, especially urine, yields ammonia in
decomposing, as is proved by the odor arising from latrines in hot
weather and so powerfully affecting the eyes and nose. Thus manure may
be said to hold ammonia compounds in storage, and from them plants
derive their nitrogen, as also many other ingredients.
“Let us summarize these details. In the nutrition of plants four
substances are of prime importance. First, carbonic acid gas, which
yields carbon, the most widely diffused of all the elements (but which
we need not dwell upon here), since plants take it chiefly from the
atmosphere, to which it is supplied unceasingly. After carbonic acid
come potash, phosphoric acid, and nitrogen, all of which the roots
extract from the soil, where it occurs in some compound or other. These
are the ingredients that the soil, if it is to remain fertile, must
have given back to it as fast as they are exhausted by the crops. Such
is the part played by fertilizers, without which the soil becomes
exhausted and ceases to produce.”
CHAPTER VIII
VEGETATION AND THE ATMOSPHERE
“The carbonic acid gas produced simply by the breathing of the great
human family amounts every year to about 160,000,000,000 cubic meters,
which represents 86,270,000,000 kilograms of burnt carbon. Piled up,
this carbon would form a mountain one league round at its base and
between four hundred and five hundred meters high. So much carbon is
required by man to maintain his natural heat. All of us together eat
this mountain of carbon in our food and in the course of the year
dissipate it all in the air, a breathful at a time; after which we
immediately begin the dissipation of another mountain of carbon. How
many mountains of carbon, then, since the world was created, must
mankind have exhaled into the atmosphere!
“We must take account, too, of the animals, which, collectively, those
of the land and those of the sea, use up a big mountain of combustible
matter. They are much more numerous than we; they inhabit the entire
globe, both continents and seas. What a quantity of carbon it must take
to sustain the life of our planet! And to think that it all goes forth
into the air, as a deadly gas, of which a few breaths would cause
death!
“Nor is that all. Fermentation, as in grape-juice and rising dough, and
putrefaction, as in decaying manure, produce carbonic acid gas. And it
needs only a light layer of manure to cause a cultivated field to give
forth between one hundred and two hundred cubic meters of carbonic acid
gas per day for each hectare.
“The wood, coal, and charcoal burnt in our houses, and especially the
quantities consumed in the great furnaces of factories—are not they
also returned to the atmosphere in the form of harmful gas? Just think
of the amount of carbonic acid gas vomited into the atmosphere by a
factory furnace into which coal is poured by the carload! Think also of
the volcanoes, gigantic natural chimneys which in a single eruption
throw up such quantities of gas that furnaces offer no comparison. It
is very clear: the atmosphere is constantly receiving carbonic acid gas
in torrents that defy computation. And yet animal life has nothing to
fear for the present or for the future, since the atmosphere, though
continually being poisoned with carbonic acid gas, is at the same time
always being purged of it.
“And what is the purgative agent commissioned by Providence to maintain
the salubrity of the atmosphere? It is vegetation, my friends,
vegetation, which feeds on carbonic acid gas to prevent our perishing
and turns it into the bread of life for our sustenance. This deadly
gas, which absorbs into itself all sorts of putrefaction, is the
choicest of nourishment for plant-life; and thus out of the bosom of
death the blade of grass builds up new life.
“A leaf is riddled with an infinite number of excessively minute
orifices, each encircled by two lips which give it the appearance of a
half-open mouth. They are called stomata. On a single leaf of the
linden more than a million can be counted, but so small are they as to
be quite invisible without a magnifying-glass. This picture shows you
how they look under a microscope. Well, through these orifices the
plant breathes, not pure air such as we breathe, but poisoned air,
fatal to an animal but wholesome for a plant. It inhales through its
myriads of millions of stomata the carbonic acid gas diffused through
the atmosphere; it admits this gas into the inner substance of its
leaves, and there, under the sun’s rays, a marvelous process follows.
Stimulated by the light, the leaves operate upon the deadly gas and
take from it all its carbon. They unburn (the word is not in the
dictionary, more’s the pity, for it gives the right idea)—they unburn
the burnt carbon, undo what combustion had done, separate the carbon
from the air with which it is bound up; in a word, they decompose the
carbonic acid gas.
“And do not think it any easy thing to unburn a burnt substance, to
restore to their original condition two substances united by fire.
Scientists would need all the ingenious means and powerful drugs they
possess to extract carbon from carbonic acid gas. This task, which
would tax the utmost resources of the man of science, leaves accomplish
noiselessly, without effort, even instantaneously, and with the sole
requirement that they shall have the aid of the sun.
“But if sunlight fails, the plant can do nothing with the carbonic acid
gas, the chief item in its diet. It then pines away with hunger, shoots
up as if in quest of the missing sunshine, while its bark and leaves
turn pale and lose their green color. Finally it dies. This sickly
state induced by the absence of light is called etiolation. It is
artificially produced in gardening for the purpose of obtaining
tenderer vegetables and of lessening or even entirely removing the too
strong and unpleasant taste of some plants. In this way some salad
greens are bound with a rush so that the heart, deprived of the sun’s
rays, may become tender and white; and thus, too, celery is banked up
and left to whiten, since otherwise its taste would be unbearable. If
we cover grass with a tile or hide a plant under a pot turned upside
down, we shall after a few days of this enforced darkness find the
foliage all sickly and yellow.
“When, on the other hand, the plant receives the sun’s rays without
hindrance, the carbonic acid gas is decomposed in no time, the carbon
and the air separate, and each resumes its original properties. Freed
of its carbon, the air becomes what it was before this admixture: it
becomes pure air, fit to maintain both fire and life. In this state it
is restored to the atmosphere by the stomata to be used again in
combustion and respiration. It entered the plant as a fatal gas, it
leaves it as a vivifying gas. It will return some day with a new charge
of carbon, which it will deposit in the plant, and then, restored to
purity once more, it will recommence its atmospheric round. A swarm of
bees goes and comes, from the hive to the fields and from the fields to
the hives, on one trip lightened and eager for booty and on the other
heavily laden with honey and returning to the comb on wearied wing. In
the same way air on coming to the leaves is charged with carbon from an
animal’s body, a burning fire-brand, or decaying matter; it gives it to
the plant and departs for a fresh supply.
“It is thus that the atmosphere preserves its salubrity despite the
immense torrents of carbonic acid that are cast into it. The plant
lives on deadly gas. Under the action of the sun’s light it decomposes
the gas into carbon, which it keeps for building up its own substance,
and breathable air, which it returns to the atmosphere. From this
carbon combined with other substances come wood, sugar, starch, flour,
gum, resin, oil, in fact every kind of vegetable product. Animal and
plant are of mutual assistance, the animal producing carbonic acid gas,
which nourishes the plant, and the plant changing this deadly gas into
air fit to breathe and into food. Thus our dependence on plants is
twofold: they purify the atmosphere and they give us food.”
CHAPTER IX
LIME
To make mortar with which masonry is held in place it is customary to
use lime. In a sort of trough lined with sand are placed lumps of stone
having a calcined appearance, and on these stones water is poured. In a
few moments the pile becomes heated to high temperature, cracks and
splits and finally crumbles into dust, at the same time absorbing the
water, which disappears little by little as it is taken up by the solid
matter or vaporized by the heat. More water is added to reduce it all
to paste, which is finally mixed with sand. The product of the mixture
is mortar. Such is the process often witnessed by Emile and Jules, who
are always surprised, that stone, by having water poured on to it,
should become hot and turn the water into jets of steam. “Lime,” Uncle
Paul explained to them, “is obtained from a widely diffused stone
called limestone or, in more learned language, carbonate of lime. The
process is of the simplest sort. It consists of heating the stone in
kilns built in the open air in the vicinity of both limestone and fuel,
so as to avoid the expense of transportation in the manufacture of a
product that it is desirable to furnish at a low price.
“A lime-kiln is about three meters high, and is lined with fire-proof
brick. An opening at the bottom serves for taking out the lime when the
firing has continued long enough. In filling the kiln it is the usual
practice to begin by laying large pieces of limestone so as to form a
sort of rude vault over the fireplace, and on this vault are piled
smaller fragments until the entire cavity is filled. The fuel used may
be fagots, brushwood, turf, or coal. After the firing has gone on long
enough, operations are suspended and the lime is withdrawn by breaking
down the vault supporting the entire mass, which crumbles and comes
crowding out at the lower opening, whence it is usually removed.
“Another method still followed in some localities and of more ancient
origin consists of filling the kiln with alternate layers of fuel and
limestone. The whole rests on a bed of fagots that serves for starting
the fire. As soon as the fire has spread throughout the mass, the
opening at the top is closed with pieces of sod in order to make the
combustion slower and more even.”
“Nothing could be simpler,” said Jules, “than lime-making. Now I should
like to know what effect the heat of the kiln has on the limestone. How
does it happen that stone turns into lime by passing through fire?”
“Limestone,” answered his uncle, “contains two different substances:
first, lime, and then an invisible substance, impalpable as air itself,
in fact, a gas, carbonic acid gas. The name of carbonate of lime given
to the limestone denotes precisely this combination. As it is when
taken from the ground, the stone contains the two substances closely
united, so incorporated indeed as no longer to have the qualities
characterizing them when apart. Heat destroys this union: the lime
stays in the kiln, and the carbonic acid gas is dissipated in the
atmosphere with the smoke from the burnt fuel. After this liberation of
the gas the lime is left in its pure state, no longer masked by the
presence of another substance, but just as it is needed by the mason
for making mortar.”
“Then all that the fire does,” queried Jules, “is just to break apart
the limestone and drive out the carbonic acid gas that it contained?”
“What takes place in the lime-kiln,” replied his uncle, “is nothing but
the separation of the lime and the gas. Now let us turn our attention
to the mortar. When lime is watered, it gets very hot, swells, cracks
open, and crumbles into a fine powder like flour. The heat that is
generated comes from the violence with which the two substances rush
together. Before absorbing water lime is called quicklime; after this
absorption, which has reduced it to powder, it is called slaked lime.
This slaked lime is reduced to a paste with water, and then well mixed
and kneaded with sand. The result is the mortar used in laying stone
and brick in order to hold the courses firmly together and give
solidity to the building.
“There is one thing I advise you to note, if you have not already done
so, since it will explain to you the part played by mortar in masonry.
Look at the water that for several days has covered a bed of lime
slaked by the masons. You will see floating on the surface small
transparent particles resembling ice. Well, these tiny fragments of
crust are nothing but stone like that from which the lime was obtained;
in a word, they are limestone or carbonate of lime. To make stone of
that kind two substances are necessary, as I have just told you: lime
and carbonic acid gas. The lime is furnished by the water, in which it
must be present in solution, since the water covers a thick bed of this
material; and as to the carbonic acid gas, it is furnished by the air,
where it is always to be found, though in small quantities. Lime, then,
has this peculiarity, that it slowly incorporates the small amount of
carbonic acid gas present in the atmosphere, and so once more becomes
the limestone that it was before.
“A similar process goes on in mortar: the lime takes back from the
atmosphere the gas that it had lost in the heat of the lime-kiln, and
little by little becomes stone again. The sand mixed with it serves to
disintegrate the lime, which thus more easily absorbs the air necessary
for its conversion into limestone. When the mortar has fully resumed
the form of limestone the courses of masonry are so strongly bound one
to another that the stones themselves sometimes break rather than give
way.
“What is known as fat lime is lime that develops great heat when
brought into contact with water, and also increases considerably in
volume, forming with the water a thick, cohesive paste. On the other
hand, poor lime develops but little heat, disintegrates slowly, and
increases scarcely any in volume. The first kind comes from nearly pure
limestone and can be mixed with a large proportion of sand, thus making
a great quantity of mortar. The second kind is obtained from limestone
having various foreign substances and will admit of but a small
admixture of sand, thus yielding less mortar than the other. Both have
the property of hardening in the air by the absorption of carbonic acid
gas which converts them into limestone.
“There is a third variety of lime called hydraulic lime, which has the
peculiar merit of being able to harden under water. It is made from a
limestone containing a certain proportion of clay. Hydraulic mortar is
used for the masonry of bridges, canals, cisterns, foundations, vaults,
in fact for all stone and brick work under water or in damp soil.”
CHAPTER X
LIME IN AGRICULTURE
“To be fertile a soil must contain limestone, sand, and clay, besides
the organic substances coming from humus and fertilizers. Now it may be
that nature has not endowed the soil with a sufficient quantity or with
any of these three constituents. Then the character of the soil must be
corrected by giving it what it lacks. That is what is called improving
the land. Thus a soil that is too sandy is improved by the addition of
limestone and clay; one that is too compact, too clayey, is improved by
adding sand and, still more, by adding limestone. Mineral substances
thus added to the soil to correct it are called correctives. These
substances coöperate also in the nutrition of plants, and from this
point of view may be regarded as mineral fertilizers.
“One of the most valuable of correctives is lime, which is
indispensable to soils lacking limestone, indispensable also to the
nutrition of nearly all our cultivated vegetables. It acts in various
ways. First, it energetically attacks vegetable substances, decomposing
them and converting them into humus. A pile of leaves that would take
long months to rot becomes in a short time a mass of humus when mixed
with lime. Hence its great utility in fields overgrown with weeds, and
in newly cleared land—in short, wherever there are old stumps, piles of
leaves, remnants of wood, and patches of heather, which need to be
decomposed. With the help of lime all these herbaceous or woody
substances are quickly converted into humus, with which the soil
becomes enriched to the great advantage of future crops.
“In the second place, lime corrects or neutralizes the acidity peculiar
to certain soils, as is proved by the following experiment. Let us mix
some vinegar, no matter how strong, with a little lime. In a short time
the smell and acid taste of the vinegar will have disappeared. Now
wherever masses of vegetable refuse, such as leaves, mosses, rushes,
old stumps, are undergoing decay, there are produced certain
sour-tasting substances or, in other words, acids, which are invariably
harmful to agriculture. This generation of acid occurs notably in turfy
soils, which have an excessive acidity favorable to the growth of
coarse rushes and sedges that are valueless to us, and at the same time
this acid is highly injurious to all our cultivated plants. Lime,
therefore, which is sure to correct this acidity, works wonders in
marshy lands, damp meadows, and turfy soils. We are warned of the need
of lime by the appearance of ferns, heather, sedge or reed-grass,
rushes, mosses and sphagnei.
“Thirdly, when once mixed with the soil, lime speedily resumes the form
it wore before passing through the lime-kiln; that is to say, it
becomes limestone, but in the shape of fine powder. This return to the
limestone condition is brought about by union with the carbonic acid
gas coming from the atmosphere or thrown off by the substances decaying
in the ground. Under this new form lime continues to play a useful part
by supplying the calcareous ingredient to soil that lacked it, and also
by preventing the clay from becoming too cohesive, too impervious to
air and water.
“The addition of lime to the soil should take place at the end of
summer, when the ground is dry. Little heaps of quicklime, each
containing about twenty kilograms, are placed at intervals of five
meters and covered with a few spadefuls of earth. In a short time the
moisture in the atmosphere reduces the lime to a fine powder, which is
then spread evenly with a shovel and covered with earth—an operation
involving no severe labor.
“Lime should never be applied with seed. Mere contact with it would
burn the young shoots. Neither should it be mixed with manure before it
is used, since the immediate result would be a total loss of great
quantities of ammonia, thrown off in gaseous form; and ammonia, as I
have explained, is one of the richest of fertilizers. Lime and manure,
therefore, should be used separately.
“Soils rich in turf, clay, or granite are the ones on which lime acts
most beneficially. Because of the important results attained by the use
of lime, its manufacture for purely agricultural purposes by certain
expeditious and effective methods is customary in many places. Thus in
Mayenne, where this application of lime has converted tracts of
uncultivated clayey land into rich pastures or into wheat fields of
exceptional fertility, lime is made in enormous kilns a dozen meters
high and supported by the cliff that furnishes the limestone and
sometimes the fuel also.
“All animal matter makes excellent fertilizer. Of this class are old
woolen rags, stray bits of leather, fragments of horn, dried blood from
slaughter-houses, and flesh not fit for human consumption. All these
substances are rich in nitrogen and phosphates, and if mixed with farm
manure they add greatly to its value. Lime furnishes us the means of
utilizing one of these substances, flesh, in the best way possible.
“Dead bodies of animals, heedlessly left for dogs and crows and magpies
to devour, should be cut up in pieces and then buried with a mixture of
earth and quicklime. This attacks the flesh and quickly decomposes it,
so that in a few months’ time there would be available a deposit of the
most powerful fertilizer instead of a useless, disease-breeding
carcass. As to the bones, resistant to the action of lime, they are
burned to render them more friable, and then reduced to powder. This
bone-dust, mixed with the fertilizer furnished by the decayed flesh,
will contribute to grain-field or pasture a rich supply of phosphorus.
To uses of this sort the farmer should put all horses and mules that
have had to be killed, as well as all large farm animals that have died
of disease.”
CHAPTER XI
PLASTER OF PARIS
“Though less important than lime, plaster of Paris is nevertheless much
used in building, especially for ceilings, molded chimney-pieces, and
in the filling of cracks and cavities. It is a white powder which is
made into a paste by adding water, prepared a little at a time and only
as fast as needed.”
“I’ve seen them do it,” Emile interposed; “the workman takes a few
handfuls of that powder out of a bag, and then he mixes it with a
little water in his trough with a trowel. He scrapes the paste all
together in his hand and uses it immediately, before making any more.
Why don’t they mix all the plaster at once, as they do with lime when
they make mortar?”
“Plaster is not all prepared beforehand for the reason that it hardens
very quickly, turns to stone, and is then unfit for use. Accordingly,
to have it in a suitable state of softness, it must be prepared at the
moment of using.”
“And what do they make that powder of that turns to stone when it is
mixed with water?”
“Plaster is made from a stone called gypsum, which, always the same as
to its nature, varies much in appearance according to its state of
purity. Sometimes it is a shapeless rock, whitish and more or less
grained; sometimes a fine fibrous mass with a silky luster; or, again,
a substance as transparent as glass and splitting into very thin scales
which show, here and there, the superb colors of the rainbow. Struck by
their beauty, workmen engaged in quarrying gypsum have given the name
of ‘Jesus-stone’ to these brilliant laminæ. Also, from their brilliance
and their cheapness, they are called ‘donkey’s mirrors.’ In ancient
times these beautiful sheets of transparent gypsum were used as
window-panes.
“Impure gypsum, in the form of shapeless rock, is used for ordinary
plaster, while pure gypsum, which comes in glass-like sheets or in
blocks of a silky appearance, is used for fine plaster, as in all sorts
of molding. The stone from which plaster is obtained occurs in
abundance in several departments of France, where it forms hills and
even whole mountains, as for example in the departments of the Seine,
the Mouths of the Rhone, and Vaucluse. For conversion into the usual
plaster of Paris this stone must be subjected to a moderate heat. To
this end it is the practice to build with gypsum blocks a row of small
vaults, and on these vaults to pile fragments of smaller size. Then the
firing is done by burning fagots and brushwood under these vaults.”
“And is it carbonic acid gas this time, too, that is driven out by the
heat, as in the manufacture of lime?” asked Jules.
“No, my friend: gypsum does not contain any carbonic acid gas. It is
made of lime, as in limestone, but united with sulphuric acid, which
heat is powerless to drive out. Besides this it contains water, which
forms a fifth of the total weight of the stone. This water, and nothing
further, escapes under the action of heat. With this expelled the
gypsum is turned to plaster.
“But this latter has a strong tendency to take on again the moisture
parted with in the kiln, and thus to become once more what it was in
the beginning—primitive stone. It is this peculiarity that renders
gypsum suitable for plaster. Moistened in the trough, the powdery
matter quickly incorporates the water that is thus restored to it, and
the whole hardens into a block having the solidity of gypsum that has
not yet passed through the kiln. Lime turns to stone by being permeated
with carbonic acid gas, which restores it to its limestone state.
Plaster becomes stone by absorbing water, which brings it back to the
state of gypsum. The transformation of lime is slow, of plaster very
rapid.
“As soon as it comes from the kiln plaster is ground under vertical
millstones and then sifted. The powder must be kept in a very dry
place, since it contracts moisture easily and then will not harden or
set, as they say, when mixed with water. You will perceive clearly
enough that after being more or loss impregnated with moisture plaster
cannot have the same tendency to absorb the water necessary to change
it into a solid mass; the substance being already somewhat soaked will
not show the same thirst when the time comes for using it. All damp
and, still more, all wet plaster is of no further use.
“Statues, busts, medallions, and various other ornamental objects are
made by casting with fine plaster of Paris. This is prepared from the
purest gypsum, those beautiful transparent scales I told you about a
little while ago. It is heated in ovens similar to those used by
bakers, and cut off from contact with the burning fuel, so as to
preserve its whiteness. The powder, which looks like fine flour, is
mixed with water and reduced to a smooth paste, which is then poured
into molds. When the plaster has set, the mold, which is in several
pieces, all joined together, is taken apart and the finished cast
withdrawn.”
CHAPTER XII
PLASTER OF PARIS IN AGRICULTURE
“In agriculture plaster of Paris has by no means the importance of
lime; nevertheless it produces excellent results on clover, sainfoin,
and lucerne. It is used in the spring for sprinkling the young leaves
when they are still damp with the morning dew. Still, foggy weather is
the most favorable for this work. Plaster also acts well on rape, flax,
buckwheat, and tobacco, but has no effect on cereals.
“The intelligent farmer puts plaster of Paris to still another use. In
every dunghill there is always going on a slow combustion, or
fermentation, giving forth ammonia in vaporous form; and this ammonia
escapes into the air as a total loss, whereas it ought to be retained
as far as possible in the manure, since the compounds of ammonia
constitute the source whence plants obtain nitrogen. Therefore to
prevent this waste, plaster is sprinkled over the dunghill. Sometimes,
too, it is sprinkled over each layer of manure as the pile rises. The
plaster absorbs the ammoniac vapors, gives them a little of its
sulphuric acid, and converts them into a compound, sulphate of ammonia,
which is proof against vaporization. Hence we say that plaster of Paris
fixes ammonia, that is to say prevents its being dissipated.
“To illustrate the fertilizing effect of plaster of Paris on lucerne,
the following incident is related. Franklin, one of the chief glories
of the United States of North America, aware of the great fertilizing
power of plaster, wished to extend the agricultural use of this
substance among his fellow-citizens; but they, clinging to old customs,
would not listen to him. To convince them, Franklin spread plaster over
a field of lucerne by the side of the most frequented road leading out
of Philadelphia, but spread it in such a way as to form letters and
words. The lucerne grew all over the field, but much taller, greener,
and thicker where the plaster had been applied, so that the passers-by
read in the field of lucerne these words traced in gigantic letters:
‘Plaster of Paris was applied here.’ The ingenious expedient was a
great success and plaster was very soon adopted in agriculture.”
“The doubters must have been convinced,” said Jules, “on seeing those
big green letters rising above the rest of the lucerne. Did not
Franklin do some other remarkable things? I remember the name; I have
seen it several times in books.”
“Yes,” replied his uncle, “Franklin became by his learning, one of the
most remarkable men of his time. Among other things, we owe to him the
invention of the lightning-conductor, that tall pointed iron rod
erected on the roofs of buildings to protect them from the thunderbolt.
It was he who first had the superb audacity to evoke the lightning from
the midst of the thunder-clouds, to direct it according to his wishes,
and to bring it to his feet that he might study its nature. One stormy
day in 1752 he went out into the country near Philadelphia in company
with his young son who carried a kite made out of a silk handkerchief
tied at the four corners to glass rods. A pointed piece of metal
terminated the apparatus. A long hemp cord, with a shorter cord of silk
tied to the lower end, was fastened to the kite, which was then sent up
toward a black thundercloud. At first nothing happened to confirm the
previsions of the American sage, and he was beginning to despair of
success when there came a shower of rain and with it a flash of
lightning. The wet cord proved a better conductor than when dry.
Without thinking of the danger he ran, and transported with joy at
having brought within his reach that which causes thunder, Franklin put
his finger near the cord and made little spurts of fire dart out,
lighted brandy from these sparks out of the sky, and only brought his
perilous experiment to an end when he had fully determined the origin
and nature of thunder and lightning. This was the way he studied the
mystery at close quarters, discovered its nature, and finally succeeded
in protecting buildings by means of a pointed iron rod.
“Benjamin Franklin was born in Boston, North America, in 1706. He was
the youngest [2] of seventeen children. Hence, as his father was a poor
tallow-chandler and soap-boiler, he could not acquire at home anything
beyond a knowledge of reading, writing, and arithmetic. At ten years of
age he was taken from school and set to performing small tasks about
the house. He cut candle-wicks and poured the tallow into the molds,
waited on customers in his father’s shop, and ran errands. His work
brought him in a few pence which he did not yet know how to spend
judiciously. He tells us the following little story on this subject,
which we may all profit by.
“‘One day,’ says he, ‘finding myself the possessor of a handful of
coppers, I ran out to buy some toys, when a little boy of about my own
age happened to pass that way with a whistle in his hand. Delighted
with the sound of the whistle, I proposed to my comrade to exchange all
my money for his musical instrument. To this he very willingly agreed.
Elated with my purchase, which I thought very fine, I returned home,
where I continued whistling to my great joy, but to the great
displeasure of the ears of my family. I told them of the magnificent
exchange I had just made. My brothers and sisters made fun of me,
saying that for the price I had paid I might have bought dozens of such
whistles at the toy-shop. Only then did it occur to me what fine things
I might have bought with my money, and I began to cry with vexation.
Chagrin at the exchange I had made now caused me more pain than the
whistle had before given me pleasure. This little incident made an
impression on me that has never been effaced and has been of service to
me on more than one occasion. Ever since, whenever I am tempted to buy
some useless thing, I say to myself, “Do not pay too much for your
whistle”; and so I save my money.’”
CHAPTER XIII
NATURAL FERTILIZERS—GUANO
“Plant-life finds a part of its sustenance provided by nature in the
atmosphere; it finds carbonic acid gas, whence it derives the carbon it
requires; but the care and ingenuity of man have to supplement these
natural resources by providing fertilizers.
“One of the chief of these fertilizers, farm manure, is furnished by
the bedding and excrement of animals. To obtain an excellent dressing
of this sort it is customary to use for bedding, as far as possible,
the straw from grain, since this, being composed of hollow stalks, is
capable of holding considerable moisture. But, as in certain cases
straw would hardly be able to absorb all the fluid matter, it is well
to make a trench in the stable and thus carry off the excess of liquid
to a reservoir outside, where another heap of straw or similar material
is in readiness to receive it. Then, at a distance from all rain-spouts
and gutters, and in the shade of trees, a substantial layer of clay is
spread on the ground, and on this is erected the pile of manure. All
around it is dug a little trench which conducts the brown liquid that
oozes from the manure, and that is known as liquid manure, into a hole
large enough to admit of the use of a bucket in drawing out the liquid.
“Liquid manure is composed of the fluid matter with which the bedding
is steeped, and it holds in solution a great part of the nutritive
constituents of the manure. Agriculture knows no richer fertilizer.
Hence care should be taken not to let it go to waste in neighboring
ditches or soak into the ground. That is why the pile is placed on a
layer of clay, which keeps the liquid manure from soaking into the
ground where it would be wasted; and it is also the reason for digging
a trench to receive this fluid matter and conduct it to the hole. When
this hole is full the liquid manure is drawn out with a bucket and
thrown back on to the dung-hill.
“Nor is that the whole of the story. A slow combustion will soon begin
throughout the pile of manure; its mass will ferment and become heated,
and as a consequence the nitrogenous constituents will decompose and
will liberate ammonia, which will escape into the air and be lost if
the fermentation is excessive. It is to avoid too rapid a heating that
the manure-pile is placed in the shade and not under the direct rays of
the sun. Moreover, the liquid manure thrown on to the heap from time to
time also moderates the fermenting process.
“Compare this careful method with the practice on most farms, where the
manure is heaped up without any precaution, without shelter from the
sun, unprotected from the drenching rains, which wash away the soluble
constituents. Think of those rivulets of liquid manure trickling away
in this direction and that, and collecting here and there in puddles of
infection. See how all the inmates of the poultry-yard scratch at the
heap, turning over and scattering its contents, and thus causing the
ammonia to escape into the atmosphere. Can such a dung-hill be as
valuable as one that is attended to properly?
“Liquid manure being the richest part of the whole pile, care should be
taken not to let escape what the bedding does not absorb. It should be
first diluted with water and then applied to the growing crops. When it
is desired for use in non-liquid form, it should be mixed with enough
earth to absorb it, and the result is an excellent fertilizer.
“In summer it is not unusual to enclose with hurdles a piece of land
soon to be cultivated, and into this enclosure a flock of sheep is
driven to pass the night under the care of the shepherd in his movable
hut, and with the protection of trusty dogs well able to cope with any
marauding wolves. The next night the flock is quartered in another
spot, and so on until the entire field has thus served, a little at a
time, as stable for the flock. The purpose of this procedure is to
utilize the excrement, both solid and liquid, left behind by the flock.
In one night a sheep can fertilize a square meter of surface. This
method of fertilizing is very effective because of the complete
absorption of the fluid matter by the soil.
“Off the coast of Peru in South America are several small islands which
form a common rendezvous for great numbers of sea-birds. Birds that
frequent the sea are all notorious for their insatiable appetite.
Constantly in search of fish, which they live on, they spend the day
exploring the surface of the waters at immense distance from land.
Nature has endowed them with prodigious flying power. To these
indefatigable rovers an aërial promenade of some hundreds of leagues
before dinner is a mere nothing. Scattered during the day in all
directions in quest of prey, they reach the islets in the evening to
spend the night, arriving in flocks so dense as to darken the sky.
Being well fed, thanks to their foraging excursions, they cover the
ground at night with a thick layer of excrement. And as this has been
going on century after century ever since the world was made, these
deposits, piled one on another, have at last become massive beds twenty
or thirty meters thick, and so hard, so compact, that to break them it
is necessary to use a pick or a petard, just as one would in quarrying
stone. Workmen operate this dung mine, and vessels from all parts of
the world fetch cargoes of this valuable material, which is called
guano. This enormous mass of dung, which has by the lapse of ages been
turned into a sort of whitish loam, gives Peru an annual revenue
amounting to sixty millions of francs.
“Guano is the strongest fertilizer known to agriculture. It is
scattered broadcast over the field when vegetation is starting, and for
the best results a rather damp time is chosen for this work in order
that the moisture may convey to the roots of the plants, by gradual
infiltration, the soluble constituents of the fertilizer. The action of
guano on vegetation is of the promptest, most powerful sort.”
CHAPTER XIV
THE STALK OF THE PLANT
“The stalk is the common support of the plant’s various parts. It is
called annual or herbaceous when it lives only one year, as in the
potato, spinach, parsley, and all forms of vegetation that from their
soft structure belong to the class of herbs. Ligneous is the name given
to the stalk when, designed to live for a greater or less number of
years, it is made of strong woody fibers, such as we find in the trunks
of trees.
“Let us make a clean cut through any tree-trunk, that of an oak for
example. We shall find it divided into three parts: in the center the
pith or marrow, very slightly developed; around the marrow the wood
proper; and, finally, on the outside, the bark. A closer examination
shows that the wood is formed of concentric layers which are indicated
in the cross-section by a series of circles having the marrow for a
common center. These layers are called ligneous zones or, since one is
formed every year, annual layers. During the summer there is a downward
flow, throughout the tree, of a peculiar liquid, the descending sap,
which constitutes the fluid nourishment of the tree. This liquid runs
between the wood and the bark and becomes, little by little in its
course, on one side a layer of wood which attaches itself to the outer
surface of the preceding year’s layer, and on the other side a thin
sheet of bark which is added to the inner surface of the bark already
formed.
“Thus each year both bark and wood form a new layer; but this added
layer is applied in opposite ways in the two instances,—outside on the
wood, inside on the bark. The wood thus encircled from year to year by
new layers increases in age toward the center and becomes younger and
younger toward the circumference, whereas the bark, lined every year
with a fresh sheet, shows its youth on the inside and its age on the
outside. The first buries inside the trunk its decrepit and dead
layers; the second thrusts its old layers outside, where they crack and
fall off in large scales. This aging process is simultaneous on the
outside and in the center of the tree-trunk; but between the wood and
the bark life is always at work, creating fresh accretions.
“Here are some experimental proofs of this annual formation of a
ligneous layer. A strip of bark is removed from the trunk of a tree,
and on the wood thus laid bare is fastened a thin sheet of metal. The
bark is then replaced and bound with ligatures so that the wound may
heal. We will suppose ten years have passed. The bark is raised again
at the same place. The metal sheet is no longer visible; to find it you
must bore deep into the wood. Now, if you count the ligneous layers
removed before reaching the metal sheet, you will find precisely ten,
just the number of years that have passed.
“A number of observations like the following are familiar: Some
foresters cut down a beech bearing on its trunk the date 1750. The same
inscription was found again in the inner substance of the wood, but to
reach it they had to cut through fifty-five layers on which no mark
whatever appeared. If now, we add 55 to 1750 we obtain precisely the
year when the tree was felled, or 1805. The inscription carved on the
trunk in the year 1750 had passed through the bark and reached the
layer of wood that was then outermost. Since that event fifty-five
years had passed and new layers, exactly the same in number, had grown
over the first.
“Thus a tree is composed of a succession of woody sheaths, the outer
ones enveloping the inner. The stem or trunk contains them all; the
branches, according to their age, contain more or fewer. Each one
represents a single year’s growth. The woody sheath of the present year
occupies the exterior of the trunk, immediately under the bark; those
of former years occupy the interior, and the nearer they are to the
center the older they are. The layers of future years will come one at
a time and take their places over preceding layers, so that what is now
the outermost layer will in its turn be found embedded in the body of
the trunk.
“Of all these ligneous zones of unequal age the most important to-day
is the outside one; its destruction would cause the death of the tree,
since through it the nutritive juices of the earth reach the buds,
leaves, and young branches. In their time the interior layers, one by
one, when they formed the surface, rendered the same service to the
buds of their day; but now that these buds have become branches the
inner layers have only a secondary office, or even none at all. Those
nearest the outside still have some aptness for work and help the layer
of the year to carry the juices from the earth to the branches. As to
the innermost ones, they have lost all activity; their wood is hard,
dried up, encrusted with inert matter. In their decrepitude these
interior layers are incapable of service in the work of vegetation; the
most they can do is by the support of their firm woody structure to
give solidity to the whole. Thus the tree’s activity decreases from the
outside toward the center. On the surface are youth, vigor, labor; in
the center old age, ruin, repose.”
CHAPTER XV
THE ROOT
“The stalk or trunk is the upward-growing part of the plant, and needs
air and light. The root, on the contrary, is the downward-growing part,
and it needs soil and darkness. The extreme ends of the root’s various
subdivisions are always growing, always young, of delicate structure,
and for that reason admirably fitted for imbibing, very much as a fine
sponge would do, the liquids with which the soil is impregnated.
Because of their facility in absorbing moisture these ever-growing
tip-ends are called spongioles. The spongioles terminate the rootlets,
that is to say the final subdivisions of the root, subdivisions known
as root-hairs on account of their resemblance to real hair.
“The root takes various forms, which are all reducible to two
fundamental types. Sometimes it consists of a main body or tap-root,
which sends out branches as it bores deeper into the soil. This
designation, tap-root, is a common and familiar term. Sometimes the
root assumes the form of a tuft, a bunch of rootlets, simple or
branching, which, springing from the same point, continue to grow at a
nearly equal rate and on an equal footing as to importance. Roots of
this sort are commonly known as fibrous roots.
“As a general rule, the growth of the root keeps pace with that of the
stem or trunk. Thus the oak, elm, maple, beech, and all our large trees
have a vigorous, deep-growing root as anchorage for the enormous
superstructure, to brace it firmly against the wind. But there is no
lack of lowly herbage that has roots quite out of proportion to the
other parts,—veritable tap-roots of greater size and vigor than many a
plant of far greater aërial development can boast. To this class belong
the mallow, carrot, and radish. Lucerne has for support to its meager
foliage a root that bores two or three meters into the ground.
“An agricultural practice of supreme interest is based, at least
partly, on the excessive development of certain roots. The plant is a
laboratory where life converts into nutritive matter the manure from
our stables and poultry-yards. A cart-load of dung becomes at the
farmer’s pleasure, after passing through one sort of plant or another,
a crop of peas or beans, a basket of fruit, or a loaf of bread. Hence
this fertilizer is a very precious thing which nothing can replace and
which must be utilized to the very utmost. The nourishment of us all
depends on it. Enriched with this fertilizer, the soil produces, we
will say, a first harvest of wheat. But wheat with its bunch of short
and fine roots, has drawn only upon the upper layer of fertilizing
material, leaving intact all that the rain has dissolved and carried
down into the lower layers. It has performed its mission admirably, it
is true; it has made a clean sweep and converted into wheat all the
fertilizer contained in the layer of soil accessible to its roots, so
that if wheat were sown a second time no harvest would be obtained. The
soil, then, is exhausted on the surface, but in its underlying strata
it is still rich. Well, what crop shall we choose for the utilization
of these lower strata and the production of still further supplies of
food? It cannot be barley, oats, or rye, since their little fibrous
roots would find nothing to glean in the surface soil after the first
crop of wheat. But it will be lucerne, since this plant will send down
its roots, each as thick as your finger, to the depth of one, two, or
even three meters, if need be, and give back the fertilizer in the form
of forage, which, with the help of the animal that feeds on it, will be
converted into nutritious meat, valuable dairy products, excellent
wool, or, at the very least, animal power for draft service or other
work. This succession of two or more different kinds of crops for the
utmost utilization of a given area of prepared soil is called rotation
of crops, of which there will be more to say later.
“Deep roots, so admirably adapted to the utilization of the lower
strata of the soil, become in other circumstances a source of serious
difficulty. Suppose a tree is to be transplanted. Its long tap-root
will make the operation difficult and hazardous. You must dig deep,
both in pulling it out and in replanting it; and then you must be
careful not to injure the root, for it is all in one piece and if it
does not take hold and grow the sapling will die. In this case it would
be much to the tree’s advantage to have fibrous roots running down only
to a slight depth; it could then be pulled up easily, and if some roots
perished in the operation enough would be left intact to insure the
success of the transplanting.
“This result can be obtained: it is no difficult matter to make the
tree lose its tap-root and acquire, not a regular bundle of roots of
even length; but a short and much ramified root that possesses the
advantages of the bunch of small roots without having its shape. Thus
in nurseries where young trees remain for some years before being
transplanted, after two years’ growth a spade is passed under the
surface of the soil to cut off the main root, which would in time
become a deep tap-root. The stump that remains then branches out
horizontally without going deeper. Another way is to pave the nursery
bed with tiles. The tap-root of the young tree pushes downward until it
reaches this barrier, where it is straightway forced to stop growing in
depth and compelled to send out lateral branches.
“The kind of root we have thus far been talking about is primordial,
original; every plant has it on emerging from the seed; it appears as
soon as the seed germinates. But many plants have other roots that
develop at different points of the stem, replacing the original root
when that dies, or at least coming to its aid if it continues to live.
They are called adventitious roots, and they play a highly important
part, notably in certain horticultural operations such as propagating
by slips and layers, which we will talk about later.
“Besides these two operations, the object of which is to multiply the
plant, it is customary to prompt the growth of adventitious roots
either for the purpose of fixing the plant more firmly in the ground or
in order to increase its yield. The best way to attain this result is
to bank up the earth at the base of the stalk. This process is
sometimes called earthing up. The buried portion soon sends out a great
number of roots. Indian corn, for example, if left to itself is too
poorly rooted to resist wind and rain, which beat it down. In order to
give it greater stability the farmer earths up the corn. In the earth
banked up at the base of the stalk bundles of adventitious roots form
and furnish the plant a firmer support.
“Wheat stalks bear on their lower ends buds which, according to
circumstances, perish to the detriment of the harvest or develop into
roots and promote the growth of more ears of grain. Let us suppose
wheat has been sown in the autumn. In that cold and rainy season
vegetation is slow, the stalk grows but little, and the various buds
remain very close together almost on a level with the ground. But if
they are favored by having damp soil near them, these buds send forth
adventitious roots which nourish them directly and promote a fullness
of growth that the ordinary root by itself could not have secured. Thus
stimulated by nourishment, these buds develop into so many
wheat-stalks, each one ending at a later period in an ear of grain. But
if wheat is sown in the spring, its rapid growth under the influence of
mild weather brings the buds too high for them to send out roots. The
stalk then remains single. In the first case from one grain of wheat
sown there springs a cluster of stalks producing as many ears; in the
second case the harvest is reduced to its lowest terms: from one grain
of wheat one stalk, one ear. Hence this development of the lower buds
of cereals is of the greatest importance. To obtain it, or, in
agricultural terms, to make the wheat send up suckers, the lower buds
must send down adventitious roots, as they will do if they are brought
into contact with the soil. To this end, shortly after germination a
wooden roller is passed over the field, and this roller, without
bruising the young stalks, pushes them deeper into the ground.”
CHAPTER XVI
BUDS
“Let us take a branch of lilac or any shrub. In the angle formed by
each leaf and the branch that bears it, an angle called the axil of the
leaf, we shall see a little round body enveloped in brown scales. That
is a bud or, as it is also named, an eye.
“Buds make their appearance at fixed points, and it is the rule for one
to form in the axil of each leaf; it is also the rule for the tip-end
of the branch to bear one. Those situated in the axils of the leaves
are called axillary buds, and those that are found on the ends of
branches, terminal buds. They are not all equally vigorous, the
strongest being at the top of the branch, the weakest at the bottom.
The lower leaves even shelter such small ones in their axils that only
the closest scrutiny will reveal them. These diminutive buds often
perish without developing unless artificially encouraged to do so. On a
lilac branch it is easy to note these differences of size from bud to
bud.
“Both terminal and axillary buds are divided into two classes. In
developing some sprout up and produce only leaves; these are called
leaf buds. When fully developed they become shoots or scions, and
finally branches. Others push upward but little and bear only flowers
or leaves and flowers simultaneously. They are called flower buds, or
simply buds. It is very easy to distinguish one kind from the other on
our fruit-trees, the leaf buds being long and pointed, the flower buds
round and thicker.
“All summer long the leaf buds grow in the axils of the leaves; they
are gaining strength to go through the winter. Cold weather comes and
the leaves fall, but the buds remain in their place, firmly implanted
on a ledge of the bark, or a sort of little cushion, situated just
above the scar left by the falling of the adjacent leaf. To withstand
the rigors of cold and dampness, which would be fatal to them, winter
clothing is indispensable. It consists of a warm inner envelope of
flock and down, and a strong outer casing of well varnished scales. Let
us examine for instance the bud of a chestnut-tree. Within we shall
find a sort of wadding enswathing its delicate little leaves, while on
the outside a solid cuirass of scales, arranged with the regularity of
tiles on a roof, wraps it closely. Furthermore, to keep out all
dampness, the separate pieces of this scale armor are coated with a
resinous cement which now resembles dried varnish, but softens in the
spring to let the bud open. Then the scales, no longer stuck together,
separate, all sticky, and the first leaves unfold covered with a
velvety red down. Nearly all buds, at the time of their spring travail,
present in different degrees this stickiness resulting from the
softening of their resinous coating. I will mention especially the buds
of the ash, alder, and, above all, the poplar, which when pressed
between the fingers emit an abundant yellow glue, of bitter taste. This
substance is diligently gathered by the bees, which use it to make
their bee-glue, that is to say the cement with which they stop the
fissures and rough-coat the walls of their hive before constructing the
combs. Under its modest appearance the bud is a veritable masterpiece:
its varnish excludes dampness; its scales protect it from harmful
atmospheric influences; its lining of flock, wadding, downy red hair,
keeps out the cold.
“The scales form the most important part of the bud’s winter clothing.
They are nothing more nor less than tiny leaves hardened and toughened,
in short so modified as to serve the purpose of protection. The leaves
immediately under them and constituting the heart of the bud have the
usual form. They are all small, pale, delicate, and arranged in a
marvelously methodical manner so as to take up the least possible room
and at the same time to be contained, all of them, despite their
considerable number, within the narrow limits of their cradle. It is
surprising what a quantity of material a bud can make room for under
its sheath of scales in a space so small that we should find it
difficult to pack away there a single hemp-seed; and yet it holds
leaves by the dozen or a whole bunch of flowers. The bunch enclosed in
a lilac bud numbers a hundred and more blossoms. And all this is
contained in that narrow cell, with no tearing or bruising of any
portion of it. If the various parts of a bud were disconnected, one by
one, if the delicate arrangement were once undone, what fingers would
be clever enough to put it together again? The principal leaves lend
themselves to a thousand different modes of arrangement in order to
occupy the least space possible. They take in the bud the form of a
cornet; or they roll themselves up in a scroll, sometimes from one edge
only, sometimes from both; or they fold up lengthwise or crosswise; or
they may roll up into little balls, or crumple up, or fold like a fan.”
CHAPTER XVII
ADVENTITIOUS BUDS
“Buds such as we have been considering appear in the spring and then
spend the summer in gaining strength, after which they remain
stationary and as if wrapped in deep sleep all through the winter. The
following spring they wake up and grow into branches or blossom into
flowers. It is plainly to be seen that these dormant buds, as
arboriculture calls them in its picturesque language, must, in order to
withstand the summer heat and the winter’s cold, be clothed so as not
to be parched by the sun or killed by the frost. They are all in fact
covered with a wrapping of scales, and for that reason are called scaly
buds. Buds of this class are found in the lilac, chestnut, pear, apple,
cherry, poplar, and in fact nearly all the trees of our country.
But if a tree can wait and devote a whole year to the development of
its buds, which are clothed in a sheath of scales because of this
waiting, there are a multitude of plants that have only a limited time
at their disposal: they live only a year, and hence are called annuals.
Such are the potato, carrot, pumpkin, and a great many more. In a few
months or days they must hastily develop their buds. These, not having
to pass through the winter, are never enveloped in protecting scales:
they are naked buds. As soon as they appear they elongate, unfold their
leaves, and become branches taking part in the work of the whole. Very
soon, in the axils of their leaves, other buds make their appearance
and behave like their predecessors; that is to say, they develop
quickly into branches which in their turn produce other buds. And so on
indefinitely until winter puts a stop to this scaffold of branches and
kills the whole plant. Thus annuals ramify rapidly. In one year they
produce several generations of branches implanted one on another,
sometimes more, sometimes fewer, according to their species and their
degree of vigor. Their buds, designed for immediate development, are
always naked. On the contrary, those forms of vegetation that have a
long life, such as trees, ramify slowly; they have only one generation
of branches a year, and their buds, destined to live through the
winter, are scaly.
Certain examples of plant-life have both kinds of buds. Such, for
instance, are the peach-tree and the grape-vine. At the end of winter
the vine-shoot bears scaly buds lined with flock, and the peach
branches scaly buds coated with varnish. Both belong to the class of
dormant buds: they have slept all winter in their sheaths of fur and
scales. In the spring they develop into branches according to the
general rule; but at the same time there appear in the axils of the
leaves other buds without any protecting covering, and these develop
immediately into branches. Thus the grape-vine and the peach-tree beget
two generations in one year: the first, the issue of the scaly buds
that have endured the winter; the second, naked buds formed in the
spring and developing very soon after their formation. The branches
arising from these latter finally give birth to scaly buds, which sleep
through the winter and reproduce the same order of things the following
year.
“Both axillary and terminal buds are in the normal order of plant-life:
they appear in all forms of vegetation that live several years. But
when the plant is in danger, when by some accident the regular buds are
lacking or insufficient, others spring into being here and there at
haphazard, even on the root if necessary, to restore a languishing
vitality and put the plant once more in a flourishing condition. These
accidental buds are to the part of the plant above the ground what
adventitious roots are to the part below the ground: the menace of the
moment calls them into existence at any endangered point. The edges of
the wound caused by the lopping off of a branch, the part of a
tree-trunk constricted by a band, portions of the bark injured by
contusion, these are the points where they appear by preference. They
are called adventitious buds, but their structure does not differ from
that of normal buds.
“Adventitious buds lend themselves to valuable uses. Suppose a number
of young saplings to be planted at proper intervals in the ground. If
they are then left to themselves these saplings grow each into a single
trunk and form collectively a wood or forest. But it may be of
advantage to replace each of these single trunks by a group of several
trunks. In that case the young plantation is cut down to the level of
the ground, and around the edge of each cross-section there presently
spring a number of adventitious buds which shoot up into an equal
number of stems, so that each sapling that would have developed only
one trunk is transformed into a stump from which start numerous sprouts
or suckers, all of the same age and strength. Then instead of a wood or
forest we have a growth of underbrush, or a copse. When the suckers
have acquired the desired size, a fresh cutting back lays them low and
induces a still denser growth of shoots by multiplying the number of
wounds. It is thus that from a single stock, repeatedly cut back and as
often reinvigorated by the growth of adventitious buds, a quantity of
wood is obtained exceeding that produced by the free and solitary
development of one tree.
“Spared by the axe, the poplar rises in a majestic obelisk of verdure.
The willow, so ungraceful in appearance along the banks of our ditches,
with its shapeless top bristling with shoots sticking out in all
directions, is, in its natural state, a tree of rare elegance on
account of the suppleness of its branches and the fineness of its
foliage. Considered as a thing of beauty, it certainly has nothing to
gain by man’s interference with its mode of growth. But, alas,
productivity does not always go hand in hand with beauty; and if it is
desired to make these two trees, the poplar and the willow, produce a
great mass of branches and fire-wood, decapitation, repeated
periodically, transforms them into pollards, seamed with scars, gaping
with bleeding wounds, disfigured with bruises, but at the same time
contending against all this hard usage by a never-failing growth of
adventitious buds which constantly replace with increasing prodigality
the brushwood that has fallen victim to the axe.
“To finish the subject of adventitious buds—buds that persist in
multiplying even when the parent stock languishes, and that withstand
destruction until utter exhaustion has set in—let us recall for a
moment certain weeds such as dog’s-tooth grass, cock-spur grass, and
other grasses that are so hard to keep out of our garden paths unless
we do something more than merely rake the surface of the ground. You
may have taken infinite pains, we will say, to clean the paths, and
have left them immaculate, or at least you think so. But you are
mistaken. In a few days the grass has all come back in richer tufts
than ever. The reason is plain enough now: your raking simply cut back
the stems, leaving wounds that immediately covered themselves with
adventitious buds, which quickly sent up new stalks. Thus, instead of
destroying, you have multiplied. The only way to clear the ground of
weeds is to pull them up by the roots; that done, you may consider the
job well done.”
CHAPTER XVIII
BULBS AND BULBLETS
“After attaining the requisite degree of strength the buds of certain
plants leave the parent stalk and, if we may so express it, emigrate;
that is to say, they detach themselves and take root in the earth, to
draw nourishment directly therefrom. Now it is evident that a bud
designed for independent development cannot have precisely the
structure of one destined never to leave the parent stem. To satisfy
its first needs before roots capable of nourishing it have been sent
down into the soil, it must of necessity have a certain prepared store
of nutriment. Therefore every bud that emigrates carries a supply of
food with it.
“There is cultivated in gardens a pretty little lily native to high
mountains, bearing orange-colored blossoms, and known as the
bulbiferous lily. Here is a piece of the stalk with its buds situated
in the axils of the leaves. These buds must pass through the winter and
develop the following spring. They are covered with succulent scales,
very thick, tender, and fleshy, good for nourishment as well as for
protection. This store of provisions makes the bud quite plump. Toward
the end of summer some of these buds leave the mother plant; they fall
at the slightest wind, scatter on the ground, and are henceforth given
over to their own resources. If the season is a wet one, many of them,
still in place at the axils of the leaves, send out one or two little
roots that hang in the air as if trying to reach the ground. Before
October arrives all the buds have fallen. Then the mother stalk dies.
Soon the autumn winds and rains cover the scattered buds with dead
leaves and mold. Under this shelter they swell all winter from the
juices of their scales, plunge their roots into the ground little by
little, and, behold, in the spring each one displays its first green
leaf, continues henceforth its independent growth, and finally becomes
a plant like the original lily.
“The fleshy, scaly buds destined to develop independently of the mother
stalk are called bulblets. No plant known to agriculture could furnish
us so striking an example of bud-emigration as the bulbiferous lily;
but in our kitchen gardens we have garlic, which acts in almost the
same way. Take a whole head of garlic. On the outside are dry, white
wrappings. Strip these off and underneath you will find large buds
which can easily be detached one by one. Then come more white wrappings
followed by new buds, so that the entire head is a package of alternate
wrappings and buds.
“These wrappings are the dried-up lower portions of the old leaves of
the plant, leaves blanched where the soil covered them, and where they
still remain, and formerly green where exposed to the air, though that
part is now lacking. In the axils of these leaves buds have formed
according to the general rule; only, as they are destined to develop by
themselves, they have stored up supplies in their thickened scales, and
that is what makes them unusually large. Split one of them lengthwise.
Under a tough sheath you will find an enormous fleshy mass forming
almost the whole of the bud. That is the storehouse. With such supplies
of food the bud is well able to take care of itself. And, in fact, when
a market-gardener wishes to raise a crop of garlic, he does not have
recourse to the seed; that would take too long. He turns his attention
to the buds; that is to say, he plants in the ground, one by one, the
bulblets of which the heads of garlic are composed. Each of these
bulblets, sustained at first by its own reserves of food, puts forth
roots and leaves and becomes a complete garlic plant.
“From the bulblet to the bulb, from garlic to an onion, there is but a
single step. Let us split an onion in two from top to bottom. We shall
find it composed of a succession of fleshy scales compactly fitted
together. In the heart of this cluster of succulent scales, which are
nothing but leaves so modified as to form a food-storehouse, are found
other leaves of normal shape and green color. An onion, then, is a bud
provisioned for an independent life by the conversion of its outside
leaves into fleshy scales; and it is called a bulb, not a bulblet,
because of its size, the latter term being the diminutive form of
‘bulb.’ Bulb and bulblet differ merely in size: the bulb is larger, the
bulblet smaller, and that is all.
“Every one has noticed that an onion hanging on the wall ready at hand
for the cook, is awakened to life in the course of the winter by the
heat of the room, and from within its envelope of red scales puts forth
a beautiful green shoot that seems to protest against the rigors of the
season and reminds us of the sweet pleasures of spring. As it develops,
its fleshy scales wrinkle, soften, become flabby, and finally fall off
in decay to serve as fertilizer for the young plant. Sooner or later,
however, its store of provision being exhausted, the shoot perishes
unless placed in earth. There we have a striking example of a bud that
develops independently by means of its own accumulated supplies. The
leek is also a bulb, but very slender in shape. Like the onion, it
consists of a cluster of lower leaf-parts sheathed one inside another.
Among ornamental plants having bulbs are the lily, the tulip, and the
hyacinth.”
CHAPTER XIX
TUBERS—STARCH
“There are buds that, though called to an independent existence, do
not, before separating from the mother plant, store up provisions nor
thicken their scales; but the plant itself is charged with feeding
them. When it is intended that the stem or branch shall itself maintain
the buds it bears, then, instead of coming out into the open air where
it would speedily cover itself with foliage and flowers, it remains
underground and has for leaves only rudimentary scales. It grows so
corpulent and deformed as to cease to bear the name of branch and to
take instead that of tuber. As soon as necessary supplies have been
stored up, the tuber detaches itself from the mother plant, and
thenceforth the buds it bears find in it abundant nourishment for their
separate existence. A tuber, then, is an underground branch swollen
with nutritive material and having undeveloped scales in place of
leaves, and it is also dotted here and there with buds which it must
feed.
“Let us now look at a potato. What do we see on the surface? Certain
small cavities or eyes; that is to say, so many buds, for these eyes
develop into branches if the potato is placed in favorable conditions.
On old potatoes, late in the season, the buds are seen to send forth
sprouts which need only a little sunshine to turn green and become
stalks. Agriculture makes good use of this peculiarity: to propagate
the plant it is customary to put into the ground, not the seeds, which
would yield no harvest before the lapse of several years, but the
tubers, which produce abundantly the same year. Or else the potato is
cut into pieces and each piece, planted in the ground, sends up a new
plant on condition that it has at least one eye; if it has none it rots
without producing anything.
“Furthermore, you can see on the eyes tiny little scales, which are
leaves modified to adapt them to an underground life, leaves with the
same right to the name as the tough scales of an ordinary bud. Since it
has leaves and buds the potato is therefore a branch. Should there
remain any lingering doubts on this subject, it might be added that by
earthing up the plant, that is to say by heaping soil around the stalk,
the young branches thus buried can be converted into potato-bearers;
and it might also be added that in rainy and cloudy seasons it is not
rare to see some of the ordinary branches thicken and swell up in the
open air, and thus produce potatoes more or less perfect. Accordingly
the potato is to be regarded as an underground branch swollen with
nourishment—in short, a tuber.
“Many other plants produce similar branches that grow under ground. In
this number is the Jerusalem artichoke, the tubers of which have buds
arranged two by two on opposite swellings, from front to back and from
right to left in turn, exactly as are leaves and buds on the stem.
“The potato feeds it buds on a farinaceous substance called fecula or,
in less learned language, starch. It is the very material that makes
the vegetable so rich in nutriment for us. We turn to our own account
what the plant has stored up for its young shoots. Starch is contained
in the extremely small cavities with which the flesh of the tuber is
all riddled. These cavities are called cells. They are microscopic sacs
made of a fine membrane and having no opening. Crammed full of starch
grains and crowded one against another, they compose the fleshy
substance of the potato. But these cavities are so small that a person
would strain his eyes in vain in any attempt to see them in the
cross-section of a potato. A magnifying glass is necessary. So minute
are the cells that in a piece of potato no larger than a pin’s head
there is room for dozens and dozens of them. This picture shows you,
but much larger than in nature, a potato cell with the grains of starch
it encloses.”
“How beautifully,” exclaimed Emile, “those grains of starch are
arranged in their little cubby-hole! They might be taken for a nest of
eggs. And you say there are heaps and heaps of these little starch
cells?”
“Yes, my boy; in a medium-sized potato they could be counted by
millions and millions.”
“It must be rather a curious sight to look at a little piece of potato
through a powerful magnifying-glass.”
“It is indeed one of the most curious sights, this countless multitude
of starch grains, all the same shape, all white as snow, gathered
together by tens, dozens, scores, and even more, in their delicate
little box-like cells.
“Let us perform an experiment not beyond our means; let us remove the
starch from a potato. All we need to do is to tear open the cells in
order to liberate the starch grains, and then filter them out. Watch me
do it. With a kitchen grater I reduce the potato to pulp and thus tear
the cells open. Now I put the pulp on a piece of linen over a large
glass and pour a little water through it with one hand while with the
other I keep stirring the pulp. The grains of starch from the ruptured
cells are washed away by the water and carried through the meshes of
the fabric, while the remnants of the cell-walls, being too large to
pass through, stay behind in the filter.
“Thus I obtain a glassful of turbid water. Look at it under a bright
sun. In the water a multitude of white satiny specks are falling like
so much snow and piling up on the bottom. In a few moments the deposit
has settled. I then throw away the clear water above it and have left a
powdery substance, magnificently white, which if pressed between the
fingers creaks like fine sand. It is the starch of the potato, and is
made up of such fine grains that it would take from one hundred and
fifty to two hundred to equal the head of a pin in size. Nevertheless
these grains, minute though they are, have a very complicated
structure, each one of them being composed of a large number of tiny
leaflets folded one over another. The picture I showed you just now
will serve to give you an idea of these superposed leaflets that go to
make, all together, a single grain. Now if some of this starch is
boiled in a little water, the successive leaflets of the grain open and
separate, and the whole becomes an unctuous jelly far exceeding in
volume that of the starch used.”
To prove this assertion, Uncle Paul proceeded to heat in a little water
the starch taken from the potato, and soon the powdery matter was
reduced to a beautiful pellucid jelly.
CHAPTER XX
USES OF STARCH
“That jelly,” remarked Jules, “looks just like the paste that I make
with laundry starch. Your potato starch there in the bottom of the
glass has exactly the same appearance as starch dissolved in cold water
for ironing clothes.”
“That close resemblance,” replied his uncle, “is explained by the fact
that potato starch and laundry starch are at bottom the same thing.
Both substances are chemically known as fecula; but laundry starch is
made from cereals, particularly wheat, while fecula, properly speaking,
comes either from potatoes or from various grains and roots.
“Like the starch of the potato, laundry starch is in the form of
superposed leaflets, but its grains are much smaller: ten thousand
would hardly be enough to make a pellet the size of a pin’s head. And
there are some still smaller. It would take sixty-four thousand grains
of Indian corn starch to make a pin’s head or, to be more exact, to
fill the inside of a cube measuring one millimeter on a side; and in
the case of the beet it would take ten millions. You see that in spite
of their excessive smallness, a smallness that makes them invisible to
the naked eye, the starch grains of the potato are giants in
comparison.
“It is chiefly by the varying size of their microscopic grains that the
starches of different kinds are distinguished from one another. In
substance and structure they are all alike. Placed in warm water, their
grains swell, burst, expand their leaflets, and the starch, from
whatever source, is changed into a glutinous jelly.
“Starch is the food supply of plant-life. Wherever we find buds that
are intended to develop by themselves, wherever we find germs, there
also we shall find a supply of starch serving as a sort of food
reserve. Hence this peculiar provision is met with in tubers, bulbs,
bulblets, seeds, and fleshy roots. Now when these buds and germs
develop, the starch becomes, in the process of vegetation, a kind of
sugar which, being soluble in water, can be sent to all parts of the
young plant and serve it for food.
“By certain artificial devices this same change of starch into sugar
can be brought about. The simplest of these devices is the application
of heat, which always enters into the preparation of farinaceous food.
Let us take a few examples. A raw potato is uneatable. Boiled in water
or roasted in the ashes, it is excellent. What has happened, then? Heat
has converted a part of the starch into sugar, and the tuber has become
a sugary farinaceous paste. The same can be said of the chestnut. Raw,
it is no great delicacy, although at a pinch it can be eaten; cooked,
it is worthy of all the praise we can give it. I appeal to you to back
me up in this assertion. Here, then, we have another transformation of
starch into sugar by the action of heat. Beans, peas, both as hard as
bullets in the dry state and of no agreeable flavor, are unmistakably
sweetened by being boiled in water and having their starch acted on by
heat. Our various farinaceous foods behave in the same way. Ingenuity
brings into play a more powerful agent than heat alone to convert the
starch into sugar. It is boiled in water and during the boiling a
little sulphuric acid or oil of vitriol is added. Under the influence
of this energetic fluid the starch is changed into a sugary syrup. It
is of course to be understood that this syrup, as soon as it has been
thus produced, is separated from the oil of vitriol which has served to
make it.
“The sugar thus obtained is a soft, sticky substance, and almost as
sweet as honey, but very different from ordinary sugar, which is solid
and comes in beautiful white loaves. [3] It is called starch-sugar or
glucose. Confectioners use it a great deal. When you crunch a
sugar-plum—and I am persuaded that you do not underestimate the
excellence of sugar-plums—do you know what you are eating? A
composition of starch and starch-sugar. I pass over the almond in the
center; that is beside the question.”
“Do you mean to say,” demanded Jules, “that a bag of sugar-plums comes
from such stuff as potatoes and oil of vitriol?”
“Such is undoubtedly the origin of the delicious sugar-plum,” was the
reply; “and indeed many of the delicacies of the pastry-cook, of the
confectioner, and of the manufacturer of refreshing beverages, which
you believe to be sweetened with ordinary sugar, really owe their sweet
taste to syrup made from starch—a much cheaper product than sugar. You
see the potato furnishes something else besides the modest dishes with
which it supplies our table.
“Nor is that the whole story. Starch-sugar, or glucose, is exactly the
same as the sugar of ripe grapes. With potato-flour, water, and a few
drops of oil of vitriol there is artificially produced, in enormous
boilers, the same sugary substance that the vine produces in its
bunches of grapes with the help of the sun’s rays. Now grape sugar
turns to alcohol by fermenting. Glucose must undergo a similar change.
And, as a matter of fact, in northern countries too cold to admit of
the cultivation of the vine, alcoholic liquors are made from starch
previously changed into sugar. On account of their origin these liquors
go under the general name of potato-brandy. All seeds and roots rich in
starch can be used in similar manufacture.
“Beer is a product of this sort. First barley is made to germinate by
being kept moist and warm. In the process of germination the starch is
changed into glucose for the nourishment of the young shoots. When the
little plants begin to develop, the grain is dried and ground to flour.
This mixed with water furnishes a sugary liquid which ferments, turning
partly to alcohol and finally becoming beer.”
CHAPTER XXI
HISTORY OF THE POTATO
“Next to wheat no plant in our part of the world is of so much
importance for food as the potato. Its use was not introduced into this
country until toward the end of the eighteenth century. The first
appearance of the potato among our people is a curious piece of
history. Why should I not relate it to you? It will show you what noble
efforts and perseverance are sometimes necessary to bring about the
adoption, on the part of those wedded to blind routine, of the
simplest, most natural idea, and one so rich in future possibilities.
“The potato is native to South America; it came to us from the high
plains of Colombia, Chile, and Peru. Its first appearance in Europe
dates from 1565. A century and a half later the potato flourished in
England. Its introduction into general use in France was slower. The
first dish of potatoes, then a high-priced rarity, was served at the
table of King Louis XIII in 1616.
“The royal dish is to-day at the command of the poorest; but this was
not effected without a good deal of trouble, as you will see. For a
long time the American tuber remained in our country a simple object of
curiosity to which were attributed injurious properties, and which
agriculture would have nothing to do with. Finally, toward the end of
the eighteenth century a worthy man succeeded in overcoming these
prejudices and popularized the culture of this valuable food plant. His
name is Parmentier. Remember this venerated name, my friends; he who
bore it banished famine by making the potato supply the deficiency of
wheat.
“Parmentier communicated his ideas to Louis XVI. ‘The potato,’ said he,
‘is bread already made and requiring neither miller nor baker. Take it
just as it comes out of the ground and bake it in hot ashes or cook it
in boiling water, and you will have a farinaceous food rivaling wheat.
Poor land unfit for other crops will raise it, and it will henceforth
relieve us of all fear of those terrible dearths that France has so
often suffered in the past.’
“Louis XVI listened to this proposal with eager attention, but the
difficulty was to make others listen also. In order to interest the
world of fashion in the culture of the disdained tuber the king
appeared at a public festival one day with a large bouquet of potato
blossoms in his hand. Curiosity was aroused at the sight of these white
flowers tinged with violet and set off by the dark green of the leaves.
They were talked of at court and in town; florists made imitations of
them for their artificial bouquets; in ornamental gardens they were
used for the borders; and as the surest way to royal favor the nobles
sent potatoes to their tenant farmers with orders to plant and
cultivate them.”
“Behold the potato fairly started on the right road!” interposed Jules.
“It cannot fail to become popular now, under the protection of king and
court.”
“Not so fast, my little friend. Persuasion is a good deal better than
command. The tubers patronized by royalty were thrown on the dunghill.
At most, here and there a farmer, afraid of being reprimanded, allowed
them to grow as best they could in some neglected corner.”
“And then?”
“Then the only thing to do was to convince, not the nobleman who cared
nothing for the potato except as a means for winning the king’s favor,
but the peasant himself directly interested in this affair. It was
necessary to overcome his repugnance, a repugnance that made him reject
the potato even as fodder for cattle; he must be taught by his own
experience that the tuber of ill repute, far from being a poison, is
excellent food. All this Parmentier thoroughly understood and he set to
work without delay.”
“This time he is sure to succeed.”
“Not at first and not without great pains. In the suburbs of Paris he
bought or rented for farming large tracts of land which he caused to be
planted with potatoes. The first year the harvest was sold at a very
low price. A few people bought some.”
“Now we are nearing the goal.”
“Not yet. Good is not accomplished so easily. The second year the
potatoes were given away for nothing. Nobody wanted them.”
“And Parmentier was left with the whole crop on his hands?”
“The excellent man could not find a welcome for a single basket of
potatoes. In the country they laughed maliciously at his obstinacy in
cultivating a vile root that no peasant would even feed to his pigs.
But Parmentier did not despair. A singular idea came to him: to see
whether the charm of forbidden fruit would not accomplish what he had
failed to effect by his writings, his advice, his personal example, and
his generous offers.
“A large field was planted with potatoes, and when the crop was ripe a
fence was built about the field as if to protect a most valuable
harvest. And more than this, Parmentier caused it to be trumpeted
abroad throughout the neighboring villages that it was expressly
forbidden to touch the potatoes under penalty of all the rigors of the
law against marauders. During the day the guards kept strict watch over
the field, and woe betide whoever should try to climb over the fence!”
“It seems to me,” said Emile, “that with all those prohibitions and
guards and fences Parmentier was more likely than ever to have all his
potatoes to himself.”
“Such was not his purpose; far from it. The guards kept good watch
during the day, but they had orders to stay at home at night and leave
unmolested any who might attempt to get into the field. ‘What, then, is
this plant that is guarded with such jealous care?’ the peasants asked
one another, attracted by the strictness of the prohibitory measures.
‘It must be very precious. Let us try to get some when the night is
dark.’
“Some bold marauders climbed the fence, hastily pulled up a dozen
tubers, and scampered off again, looking back to make sure they were
not pursued. Not a guard was to be seen. Word soon spread that the
field was not guarded at night. Then the pillage began in earnest: the
tubers hitherto so despised were carried off by sackfuls. In a few days
there was not a potato left in the ground.
“People came and told Parmentier of the devastation of his field. The
worthy man wept for joy; the one robbed blessed his robbers. By his
ruse he had endowed his country with an inestimable food-supply; for,
once placed in the hands of those who would consent to cultivate it,
the potato was valued at its true worth and spread rapidly.”
“Oh, what a curious story!” cried Louis, when Uncle Paul had finished;
“what a curious story! Who would have thought it took all that trouble
to make people accept a food that to-day is of such value to us? Is it,
then, so very hard to spread a good idea when it is new?”
“Very hard indeed,” replied Uncle Paul, “as those well know who make it
their mission to fight against prejudice and ignorance.”
CHAPTER XXII
ASCENDING SAP
“Now let us see how the plant is nourished by the various substances of
which we have just studied the most important. Every form of plant-life
is made up, not of a compact and uniform mass of matter with no
occasional empty spaces, but, on the contrary, with the aid of a
microscope it is seen that an infinite number of very minute cavities
called cells are interspersed throughout the body of the plant. These
cells may be regarded as extremely small closed sacs, sometimes round,
sometimes oval, but more often with irregular and angular outlines by
reason of the mutual pressure exerted by the cells. The cell-wall is
composed of an excessively fine membrane. In the pith of the elder, all
riddled like a sponge, you have an example of cells large enough to be
seen without a microscope. Other cavities are long, pointed at both
ends and swollen in the middle like a spindle. They are called fibers.
Still others form canals of uniform size throughout, as fine as a hair
and long enough to extend from the roots to the topmost leaves. These
canals are called ducts. Look closely at the cross-section of a very
dry vine-branch, and you will see a multitude of orifices into which it
would be possible to thrust a hair. Those are the openings into so many
broken ducts. Everything in the plant, absolutely everything—root,
stalk, wood, bark, leaves, flowers, fruit, seeds, no matter what—is
composed of a mass of cells, fibers, and ducts.
“That understood, let us consider the root of the plant. In its new
parts, at the tip-ends of its finest ramifications, tip-ends that we
have called spongioles, it is composed of cells just formed and
consequently tender and fitted for absorbing easily the moisture in the
soil. Spongioles, then, fill themselves much as sponges would do. That
done, conduits offer their services for conveying the liquid to the top
of the plant: they are the ducts just referred to, and comparable here
to the water-pipes in our own fountains. But if in fountains water runs
by its own weight, going from the highest to the lowest point, it is
not so with the liquid absorbed by the roots, a liquid running from
below upward. What then is the force that makes it ascend?
“This force is in the buds or, to speak more correctly, in the leaves.
Each leaf is the seat of an active evaporation whose object is to rid
the plant of the great quantity of water required for dissolving in the
soil and then conveying to the leaves the nutritive substances present
in the soil. This evaporation leaves a void in the cells that have
given up the evaporated water. But this void is immediately filled from
the neighboring cells, which give up their contents and receive in turn
the contents of the next lower layers. From cell to cell, from fiber to
fiber, from duct to duct, a similar transfer takes place at points
farther and farther away from the evaporating surface, until the
tip-ends of the rootlets are reached, where a continuous absorption
makes good the loss of moisture by evaporation. The process reminds one
somewhat of the working of our pumps, in which the piston leaves behind
it a void that is immediately filled by the water in the pipe, which in
its turn gets water from the bottom of the well. This liquid which
ascends in every plant, absorbed by the spongioles of the rootlets and
put in motion by the evaporation from the leaves, is called ascending
sap, or crude sap. The sap is called ascending because it passes from
below upward, from the roots to the branches; and it is called crude
because it has not yet undergone the preparation that will turn it into
the nutritive liquid of the plant. Thus we have learned our first
lesson, namely: ascending sap is carried especially to those parts of
the plant where buds are numerous, where leaves abound; it seeks by
preference the ends of the branches, where evaporation is most active.
“We know that the surface wood is the newest; it is formed of cells,
fibers, and ducts whose cavities are free and whose walls are
permeable. The interior wood is older; its cells, fibers, and ducts are
encrusted, stopped up, decrepit, out of use. The liquid accordingly
makes its way where circulation is possible, and ceases to flow where
the passage is obstructed. That is to say, the ascent of the sap takes
place through the sap-wood and chiefly through the outermost layers, or
those of most recent formation. Repeated experiment leaves no doubt on
this point. When a tree is cut down at the time of the sap’s greatest
activity, we find the sap-wood moist and the older wood perfectly dry.
Finally, in herbaceous plants the sap ascends through the whole body of
the stem. Suspended during the winter on account of the absence of
foliage, this ascent of the sap becomes remarkably brisk at the
awakening of vegetation. Then it is that fruit-trees shed tears, so to
speak, where the pruning-hook has left its mark; or, in other words,
the ascending sap oozes from the openings of the severed ducts. These
tears are especially noticeable in the grape-vine, where it has
recently been trimmed.
“Now what would you expect to find in this liquid if you collected some
of it as it trickles in the form of tears either from the vine or from
a fruit-tree? Many things, doubtless, you will say, since this precious
liquid is the prime source of all that the plant contains in itself. If
such is your thought, undeceive yourselves: ascending sap is little
more than clear water, and often it is very difficult for science to
prove beyond a doubt the presence in it of various substances in
solution, so minute a fraction of the whole do they compose. Among
these substances the most frequent are compounds of potash, of lime, of
carbonic acid gas, traces of phosphates, and compounds of nitrogen or
ammonia. In short, the liquid from which the plant is to derive its
nourishment is the weakest sort of broth, composed of an enormous
quantity of water and a very small proportion of dissolved substances.
These inconsiderable substances are the only or almost the only things
utilized by the plant; and the water that has collected them in
filtering through the soil, and has then carried them from the roots to
the leaves through the sap-wood, the water that forms almost the whole
of the ascending sap, is destined, as soon as the journey is
accomplished, to leave the plant and return as vapor to the atmosphere
whence it descended in the form of rain.”
CHAPTER XXIII
DESCENDING SAP
“Ascending sap, a liquid composed of a large quantity of water and a
very small proportion of dissolved nutritive substances, is absorbed in
the ground by the roots and carried to the leaves through the sap-wood.
It is not yet a nutritive fluid for the plant; it becomes so in the
foliage by a double process. First, on being distributed to the leaves,
which furnish a vast surface for evaporation, it exhales its
superabundant water in the form of vapor and thus concentrates its
usable ingredients. Then, under the influence of the sun’s rays and
through the medium of the green matter contained in the leaves, it
undergoes modifications that work a fundamental change in its
character. Among the processes here taking place, one of the best known
is the decomposition of the carbonic acid gas taken from the air by the
leaves and from the soil by the roots.
“We have seen that this gas, the plant’s chief source of nourishment,
is composed of carbon combined with the breathable part of the air, or
oxygen. Under the action of the sun’s light the leaves decompose this
gas, liberating the oxygen in a condition henceforth fit for the
respiration of animals and for combustion, while the carbon remains in
the plant, mixes with the substances brought by the ascending sap, and
with them becomes the nourishing liquid, the descending or elaborated
sap, from which all future parts of the plant are to be formed. This
liquid cannot be called wood, bark, leaf, flower, or fruit; it is not
at all like any of these, and yet it is essentially a little of them
all. An animal’s blood is neither flesh, bone, nor fleece; but bone,
flesh, and fleece are of its substance. Likewise the elaborated sap is
a liquid designed for the sustenance of all parts of the plant; it
contains matter for fruit and wood, leaves and flowers, bark and buds.
It is the plant’s blood; everything in the plant gets from it its
nourishment, its wherewithal to develop. What a wonderful, what an
incomprehensible process its production appears to us! In the crowded
ranks of the leaf-cells, where one would suppose everything to be at
rest, what activity, what transformations beyond the reach of human
science! Liquids swell the cells, ooze from one to another, transpire,
infiltrate, circulate, exchange their dissolved substances; vapors are
exhaled, gases come, others go; the sun’s light separates what was
united, unites what was separated, and the raw materials of the
ascending sap combine henceforth with the materials of life.
“The elaborated sap descends from the leaves to the twigs, from the
twigs to the branches, from the branches to the stalk or trunk, and
from the latter to the root, distributing itself here and there on its
way. It circulates between the wood and the bark. It is this sap that,
in the spring, when it is in great abundance, forms between the wood
and the bark a thin layer of slightly viscous moisture and makes the
bark easy to peel from its branch. Which of you in the month of May has
not taken advantage of this peculiarity to peel off all in one piece a
tube of bark from a very smooth twig of willow or lilac in order to
make a whistle, trumpet, or other noisy plaything, the delight of boys
of your age?
“Nothing is easier than to prove the passage of sap from above
downward. If you remove from a tree-trunk an annular band of bark, the
nourishing liquid oozes and accumulates at the upper edge of the wound,
but nothing of the sort takes place at the lower edge. Arrested thus by
a break in its path, the sap accumulates above the uncovered ring and
causes there an abundant growth of wood and bark, which piles up in the
form of a thick circular swelling, while below the ring the trunk
preserves its former size.
“A tight ligature, by compressing and obstructing the passages through
which the nutritive fluid has to pass, causes the formation of a
similar swelling above the line of stoppage. You may have seen a
sapling, bound too tightly to the stake intended for its support,
strangled by its own growth if the gardener has forgotten to loose the
band in time. Little by little the trunk swells above this band, which
is finally overgrown by the bark and even hidden within its substance.
Indeed, it is not rare to find a tree with its trunk caught fast in a
narrow passage, as for example in the crevice of a rock, and swollen
above the obstacle into an unsightly excrescence. The stoppage of the
sap in its downward course explains this phenomenon.
“If the tree-trunk is not completely encircled by the stricture, if
somewhere there is a strip of bark left free to serve as a passage, the
nourishing juice takes this way to get around the obstacle, and so
pursues its course to the roots. Then the tree continues to live. But
if the barrier is absolutely insuperable, as in the case of an
unyielding ligature or when the tree has been girdled, the sap cannot
descend to the roots to nourish them; and with the death of these the
end of the tree is not far distant.
“An important lesson remains to be drawn from these details concerning
the circulation of this nutritive liquid in plants. Henceforth, when we
fasten a plant to its prop or supporting stake, we shall be careful not
to tie the string too tight or else to loosen it at the proper time,
since otherwise we should run the risk of strangling the plant and so
causing its death.”
CHAPTER XXIV
TREE-PRUNING
“Self-preservation is the first law of a tree’s life, and next to that
the preservation of its species, which is to be perpetuated by means of
seeds. All this is perfectly natural, for no posterity would be
possible to the tree unless its own existence were maintained in the
first place. Accordingly the tree lives first for itself, accomplishing
this object by covering itself with buds that develop into branches
covered with leaves. It is indeed on the leaves that the fundamental
principles of the plant’s life are based; it is in their substance
that, with the sun’s help, the descending sap is elaborated, this sap
being the nutritive fluid, the life-blood as it were, of the vegetable
organism. The propagation of the species comes next in importance. This
duty devolves on the flower-buds or those that blossom and produce
fruit, in the center of which are the seeds.
“Thus, left to its own impulses, a tree, if vigorous and enjoying
favorable conditions, at first uses all its sap in making buds for the
increase of its own woody structure; it covers itself with stout
branches and abundant foliage before making up its mind to blossom.
Later, when its limbs are strong and the ardor of growth begins to
abate, the flower-buds appear, but usually in small numbers because a
prodigal production of fruit causes rapid decline. Copious blossoming
comes only toward the latter part of life; a tree never blossoms better
than when it is about to die, as if, foreseeing its end, it strove
before succumbing to leave behind it a numerous progeny. A thriving
tree blossoms little or not at all; a sickly tree makes haste to
blossom. But it is to man’s interest that a tree should blossom and
bear fruit as early and as abundantly as possible; we demand from it
not the branches it would give us without our intervention, but baskets
of fruit induced by our care. From this struggle between the natural
tendencies of the tree and our own needs has sprung the practice of
pruning, or the art of manipulating fruit-trees so as to obtain from
them an abundant harvest.
“Here let us examine the general principles that are to guide us in the
practice of this art. The shape to be given the tree’s superstructure
of branches and foliage is the first question we must consider. This
shape is far from being unimportant; it is, on the contrary, very
important, since the circulation of the sap and the distribution of the
sun’s rays, essential conditions to plant-life, are strictly dependent
on it. If the tree is left free to develop by itself and to take its
natural form, the sap from the roots will, under the impetus of its
ascent, always seek by preference the highest points, where growth will
in consequence proceed with vigor, while the lower parts will languish
and die out for want of sufficient nourishment. If the branches are not
properly thinned the central ones, deprived of the sun’s vivifying
rays, will remain poor, puny, more or less blanched. On the other hand,
the tree ought to fill, as far as possible, the place assigned it, in
order that there may be no unproductive space.
“These conditions prescribe the tree’s shape. First of all, it should
be symmetrical, in order that the distribution of nourishment may be
even and no part of the tree be gorged with sap while another part is
deprived of it. Secondly, the sun’s rays should be allowed to penetrate
everywhere so as to ripen the fruit and facilitate in the foliage the
important work of sap-elaboration. To attain these different objects
custom has fixed upon three principal shapes: the trellis, the pyramid,
and the goblet. In trellis pruning the tree spreads its branches
symmetrically, right and left, against a wall. The wall serves it as
support and as shelter from the wind; it also gives the foliage and
fruit additional heat and light by reflecting the sun’s rays upon them.
When pruned to take the pyramid form, the tree has its branches so
trimmed as to decrease in length regularly from the base to the summit
and to remain far enough apart to admit the light to the center. The
whole forms a sugar-loaf, a cone, into the midst of which sun and air
enter freely. It is the shape most in accord with nature. Finally, the
goblet-shaped tree has a certain number of branches of equal vigor
disposed in a circle around a central space that remains empty and thus
receives its share of sunlight without hindrance.”
CHAPTER XXV
PINCHING—BUD-NIPPING
“When the desired shape has been obtained the next thing is to keep it,
despite all opposition on the part of the tree, which revolts in its
own peculiar fashion; that is, it strives to restore the natural
conformation of its branches. Suppose, for example, that a pear-tree,
pruned after the manner of wall-fruit, has grown all out of symmetry
and developed one side more than the other. How shall the two halves be
restored to correct proportions? How shall the too vigorous part be
weakened and the too feeble part strengthened? Several methods offer
themselves.
“On the vigorous side let us cut back the branches with the pruning
shears, leaving only the base of each with a small number of buds; in
other words, let us cut them very short. On the weak side, on the
contrary, let us leave the branches intact or cut them very long, thus
leaving them the greater part of their buds. What will come of this
treatment? Since abundant foliage, the active laboratory of the
descending sap and also a kind of pump that sucks up the sap and causes
it to ascend from the roots, is the prime cause of vigorous vegetation,
the weak part, with its numerous buds developed into leafy shoots, will
grow stronger, while the strong part, with its small number of buds,
will become weaker. Both effects will tend to the same result: the
restoration of the desired symmetry.
“With the ends of the fingers and the help of the thumb-nail, it is
customary to pinch off from the too vigorous side the tips of the young
branches while they are still tender. This operation we may call
pinching. The sap that would have been used for the development of
these branches is diverted from its course and carried toward the weak
shoots, which it renews and stimulates. If the weak side itself needs
pinching to arrest shoots that impair the desired symmetry, the
operation is postponed as long as possible, while on the strong side it
is carried out very early. The sap thus turned away from the vigorous
side toward the ailing one has a whole season in which to restore the
lost equilibrium.
“Instead of limiting ourselves to pinching off the tips of the young
shoots with our thumb-nail, we can suppress them altogether while they
are still tender. This is done as early as possible on the strong side,
only the indispensable shoots being left. If it is necessary on the
weak side, it is not done until the latest possible moment. This
operation we may style bud-nipping, since the word ‘bud,’ by which we
designate the germ of the future branch when it is still enveloped in
scales, applies also for the sake of convenience to the branch already
developed but still young and tender. It is evident that nipping off
the buds from the strong part tends, even more than pinching, to
promote the desired growth of the weak part. The more branches we
suppress entirely, the fewer will be left to share the sap needed by
the branches we wish to strengthen.
“What turns aside the sap from the part pruned, pinched, or nipped,
toward the part left intact, is evidently the more or less complete
suppression of foliage. It is primarily the leaves that by the
continual evaporation of which their surface is the seat determine the
ascent of the liquid drawn from the soil by the roots. The more
numerous these leaves are at any one point, the more abundant the flow
of sap to that point; the scarcer they are, the less the flow of sap.
To diminish at any point the number of leaves by pinching, bud-nipping,
or any other means, is therefore to diminish at the same point the flow
of sap, which will go in some other direction, to the parts that have
more leaves and hence a more rapid rate of evaporation to summon the
sap. It is plain, then, that a middle course may be followed between
the pinching that partly suppresses the foliage of a young branch and
the bud-nipping that suppresses it entirely. This middle course
consists in cutting a certain number of leaves from the too vigorous
shoots; and they should be cut clean without tearing, by severing the
stem and leaving its base undisturbed.
“The easiest way for the sap to run from the roots to the foliage is
from bottom to top in a vertical line. Anything that interferes with
this course hinders also the upward impetus. Thus in branches with
sharp elbows and abrupt bends the rush of sap is slackened just as the
rate of flow of a water-current is diminished by the windings occurring
in its bed. Thus, again, in a branch having a decided incline downward
the sap moves with difficulty, because its movement toward the
extremity of this branch is in a direction contrary to that which is
natural to it. The application of this principle is evident. If we wish
to moderate a too vigorous growth of branches, we bend them toward the
ground; if we wish to stimulate a too feeble growth, we straighten up
the branches until they assume a vertical posture.
“We can also turn to account the exhausting effect of fruit-bearing.
The more fruitful a branch is, the weaker it becomes, since the use of
sap in fruit means so much the less for foliage, and it is foliage that
invigorates the branch. Accordingly we will leave the greatest possible
quantity of fruit on the strong part of our tree, and suppress it on
the weak part.”
CHAPTER XXVI
MAKING FRUIT TREES BEAR
“If one side of a tree is pruned very short and the other very long,
the natural course of the sap is to some extent diverted from the first
side toward the second, which is richer in buds and consequently in
foliage. We have just seen how this principle is utilized to check the
growth of too vigorous a part in order to stimulate that of one that is
too feeble and thus redress the balance between the two. But what would
be the result if the whole tree were pruned at once?
“Let us first see what takes place in a single branch. Pruned long, it
preserves the greater part of its buds, all of which call for
nourishment from the sap flowing in that direction; pruned short, it
keeps only a few buds, which having the sap of the entire branch at
their disposal, will receive each a supply that is superabundant in
proportion to the fewness of the buds. For example, what twelve would
ordinarily have had for consumption, two or three will now have to
themselves; and because of this superabundance of nourishment each bud
will develop much more vigorously than it would otherwise have done.
Hence if the whole tree is pruned with an unsparing hand, all the sap
drawn from the soil by the roots, having no longer a tendency to go to
one side rather than the other, will be distributed evenly; and the few
buds left intact by the pruning-shears will show a luxuriance of growth
in proportion to the supply of nourishment placed at their disposal.
Thus thorough pruning applied to the whole tree has the effect of
giving it new vigor, of rejuvenating it in some measure, or, in other
words, of replacing its worn-out branches with vigorous ones.
Accordingly when a tree has become exhausted by abundant fruit-bearing,
it is pruned without stint one year in order to restore its vigor of
growth.
“Let us now see what we should do if we had quite the opposite end in
view; that is, if we wished to make a tree blossom and bear fruit. Here
two principles will serve us as guides. First, in the fulness of its
vigor a tree puts forth long branches and thick foliage, but does not
cover itself with blossoms, bearing in fact only a few. It is not until
it has become somewhat enfeebled that it begins to flower in profusion.
Secondly, what would in the tree’s youthful strength have been a
branch-producing bud becomes in its enfeeblement a flower-bud; so that
a flower may be regarded as a branch which, instead of developing
freely and covering itself with leaves, has remained stunted, thrown
back upon itself, for lack of vigor, and has exchanged its leaves for
floral organs,—sepals, petals, stamens, pistils. Weaken a tree and you
weaken the buds; such, in a word, is the prevailing principle.
“To weaken the buds individually, the pruning-shears will be plied but
sparingly, leaving the buds almost intact; then these, being many in
number, will have so much the less for each one separately, and some of
them, especially toward the lower part of the branch, will find
themselves too feeble to contend with the others and therefore will
take the form of flower-buds, whereas they would have produced branches
and not flowers if a more thorough pruning had rid them of their
rivals.
“To weaken the tree as a whole, all that we have to do is to pinch off
or cut off with the thumb-nail the tender tips of the young branches;
then we bend these branches back so as to give them a number of crooks
and turns that will impede the circulation of the sap. Finally, the
woody branches of the preceding year are broken by the hand, sometimes
wholly, sometimes half, so that the tip is left hanging down. If the
tree is not too vigorous these three methods, pinching, bending, and
breaking, are generally sufficient to make it bear.
“But when we have to do with very exuberant vegetation, more energetic
methods are necessary. One of these we may call arching. The branches
are all bent down so that each forms an arch; that is, the tip-end of
each is pulled down to the ground and fastened there in any way that
may be easiest. This abnormal position of the branch, with its top
downward, is contrary to the ascending movement of the sap, which
consequently flows less freely to the buds. The resulting dearth is
conducive to fruit-bearing, and as soon as this effect is assured the
branches are allowed to return to their natural position; otherwise the
tree would become exhausted.
“Another method is as follows. Pruning is done very late, when the
young shoots are already some centimeters long. The sap used up in the
growth of the shoots cut off by the pruning shears is a great loss to
the tree, which, being no longer able to supply ample nourishment to
the lower buds of the branches, turns them into flower-buds.
“If these means do not suffice to make the tree bear fruit, there are
more violent ones which are employed only in the last extremity. Toward
the end of winter, before the sap has started, an incision some
millimeters wide and deep enough to penetrate the outer layers of wood
is made all around the base of the trunk. Sap, as we know, ascends
through these exterior layers, the newest, the most permeable by
liquids; so if we partially intercept its passage it will flow less
abundantly to the buds and the weakened tree will soon begin to bear.
“Still another expedient is to strike at the very source of the sap,
the roots. The foot of the tree is laid bare in the springtime, its
main roots being denuded of their covering and left thus exposed all
summer to the open air and the hot sun. No longer enjoying the coolness
and darkness necessary to their office, they furnish less nourishment
to the tree, and this scarcity causes the formation of flower-buds. A
still more drastic method, but one that would kill the tree if employed
imprudently, is to strip the roots of the refractory subject without
mercy, cutting and mutilating a certain number of them and then putting
back the earth that has been removed. A diminution in the flow of sap
must necessarily result from this surgical operation. Finally, if the
tree is small enough for the purpose, it is dug up at the end of
autumn, with care to preserve the roots as far as possible, and planted
again somewhere else. The disturbance caused by this change of place
suffices to make the tree blossom the next year.”
CHAPTER XXVII
THE SEED
“The ovary of the flower, after being fertilized by the pollen, becomes
the fruit, the apple on the apple-tree, the cherry on the cherry-tree,
the walnut on the walnut-tree, the grain of wheat in the wheat-ear, and
so on for all plants. The fruit contains seeds in greater or less
number, and sometimes only one, as in the peach, plum, and almond;
often several, as in the apple and pear; while in other instances they
can be counted by hundreds and thousands, as in the melon, the pumpkin,
and the poppy-head. The natural function of the fruit is first to
supply nourishment and then to protect its seeds by means of coverings,
these being sometimes fleshy, sometimes thin and dry, sometimes hard
and in the form of strong shells. In their turn the seeds have as their
task the propagating of the species. Every form of plant-life, from the
giants of the forest, the oak, beech, fir, and others, to the tiniest
moss, has its beginning in the seed. Every plant has its flowers, its
fruit, and its seeds. It is in the seed that vegetation is preserved in
a thriving condition through the ages; it is by the seed that every
tree, every shrub, every blade of grass propagate their kind and leave
a numerous progeny.
“Who would not like to know,” continued Uncle Paul, “something about
the formation of the seed that is sown in the ground to become either a
little plant or an enormous tree? What is inside it? How can an oak
come from an acorn and a pear-tree from the pip of a pear? I will try,
my friends, to satisfy the very natural curiosity such a mystery cannot
fail to arouse in you.
“Let us look at the fruit of an almond-tree. First it has an outside
skin, green and tender, which at maturity opens of its own accord,
dries up, folds back, and lets its contents out. Examining the latter,
we find a shell, sometimes fragile enough to be broken with the teeth,
but at other times very hard and yielding only to the hammer. Breaking
the shell, we come to the seed. Of what use are the two parts we have
just removed? We must be very stupid if we cannot recognize in them the
coverings intended to protect the seed, the wrappings that shelter the
delicate germ from cold, heat, rain, and the teeth of animals. The
outer envelope, covered with a short, velvety down, serves as a
protection against the weather; the inner one is a veritable strong-box
which we have to break between two stones before we can get at its
contents. Similar means of defense are found in all fruit, but with
wide differences in the different kinds of plants. The cherry, plum,
peach, and apricot have the hard shell, the strong-box, of the almond,
and also an outer envelope of juicy flesh. The apple and pear have
their seeds or pips, as they are called, snugly ensconced in five
little cavities grouped in the shape of a five-pointed star, as may be
seen in a cross-section of the fruit. These little cavities have walls
of a tough, scaly material somewhat resembling horn, while all about
them is a thick rampart of flesh. Beans and peas are arranged in a sort
of long sheath that opens in two pieces. Chestnuts are packed in a bag
covered with long prickles. All these protecting coverings, whatever
their shape and character and degree of toughness, form part of the
fruit.
“Let us go back to the almond. The shell being broken, we come to the
seed, which is all in one piece. This seed, as we have just seen, is
protected by two coverings, the inner one of which is a very firm, hard
casing called the stone. As a protection is it enough? Not quite.
Beneath the exterior defensive armor comes the fine inner covering that
wraps the seed closely and shields it from contact with the hard shell.
This covering is double and is composed on the outside of a reddish
skin and inside of an extremely thin and flexible white cuticle.
Similar double clothing is found on all seeds. The inner one is always
very fine, as indeed it should be, since it comes next to the most
essential and delicate part of the seed. Do we put coarse cloth, rough
woolen stuff next to the tender flesh of a new-born babe? Certainly
not; but rather the finest of linen, and over that the woolen fabric.
The plant does the same with its tender young seeds. The outer
envelope, much firmer and tougher than the inner, looks very
differently in different plants. In the almond and walnut it is a
reddish skin, and so it is also in the stones of the peach, apricot,
and plum. In the pips of the pear and apple it is a tough brown casing.
In beans it is smooth and shiny, sometimes quite white, sometimes black
and white, sometimes speckled with red spots. In addition, peas and
beans of all kinds have at one point on their surface a sort of little
oval eye. To this eye was once attached a small short cord that
fastened the seed to the wall of the pod and served as a pipe for
supplying it with nourishment. All seeds have this attachment, or
nursing-cord, as we may call it, but not all have so clearly marked as
in the bean the eye where the cord is fastened.
“After the two coverings of the seed have been removed, which is very
easily done when the almond is new, there remains a white object, firm
and savory, the eatable part of the fruit of the almond-tree. That
object is the seed proper; that is to say, the part that would have
become a tree if planted in the ground. It is round at one end and
rather pointed at the other. From the pointed end projects a little
nipple, and all around the edge runs a slight furrow indicating that
here the seed may be split in two. Let us insert the point of a knife
into this furrow and exert a little pressure. One half will come away
and the other half will show us what you see in this picture.
“The little pointed nipple (r) is called a radicle. It is the part
that, if allowed to grow, would push down into the earth, send out
branches there, and become the root. At the point marked g is a compact
bunch of tiny leaves, all white, forming a kind of bud, but one that is
much feebler and more delicate than buds that grow on branches. It is
called a gemmule. This bud will unfold and send forth the first leaves.
Finally, the narrow line of demarcation between the radicle and the
gemmule is called the tigella, and from it the trunk of the tree will
take its start. Such is the almond-tree in its seed. The large tree
that will send out a mass of branches and foliage into the air and
thrust powerful roots into the ground is now contained in an
insignificant corpuscle just large enough to be seen.”
CHAPTER XXVIII
THE SEED’S FOOD-SUPPLY
“When it has leaves and roots that are sufficiently developed, the
little almond-tree will nourish itself by drawing what it needs from
the earth and air. But until then it must live, it must grow stronger,
and it must increase a little in size. As nothing can come from
nothing, the germinating seed must find somewhere the material for its
first growth. This cannot be in the soil so long as the radicle is
nothing but a point, incapable of any work; neither can it be in the
air so long as the little leaf-bud has not unfolded and developed into
foliage. The seed, then, must have a certain supply of nutriment stored
up within itself. Let us turn our attention to this prepared stock of
food.
“In the almond we have studied the gemmule or leaf-bud, the radicle,
and the tigella; but there still remain two large pieces, easily
separable from each other, and constituting by themselves alone almost
the entire bulk of the seed. These two pieces are the plant’s first
pair of leaves, but leaves of a peculiar structure, being very thick,
fleshy, and relatively enormous in size. They are the alimentary
reservoirs, the storehouses of food from which in its beginning the
young plant must draw its sustenance. When germination begins, these
two large leaves, swollen with nutritive matter, yield little by little
a part of their substance to the tiny plant and suckle it, as it were.
They might therefore be called vegetable udders, nursing-leaves, but
science calls them cotyledons. The unhatched chick in its shell has the
yolk of the egg to furnish substance for its growth, the young lamb has
its mother’s milk, the germ of the plant has the juice of the
cotyledons.
“The same structure, with two cotyledons of great size and easy to
observe, may be found in the broad bean, pea, kidney bean, and acorn,
and in the stones of the peach, apricot, and plum. It would also be
found in the pips of pears and apples as well as in the seeds of most
of our cultivated plants, but more difficult to distinguish in
proportion to the smallness of the seed. In every instance the seed
would be found to have two cotyledons as food-storehouses, and also a
gemmule and a radicle united by the tigella. Other plants, on the
contrary, like maize, wheat, and the other cereals, as also the lily,
tulip, and iris, have but one cotyledon, one nursing-leaf for the new
vegetable organism.
“It is not always easy, especially when the seed is very small, to
ascertain whether it has two cotyledons or only one; but as soon as
germination has begun, this difficulty disappears. Then the seed with
two cotyledons is seen to push up two leaves, the very first to appear,
situated opposite each other, and very often differing in shape from
those that come later. In the radish, for example, they are
heart-shaped; in the carrot, long and narrow like little tongues. These
two leaves that precede the others are known as seminal leaves. They
come from the two cotyledons, which generally open in the air and grow
green while nourishing the young plant with a part of their substance;
but sometimes, as in the acorn, they remain hidden underground. On the
other hand, seeds having but one cotyledon come up with only one
seminal leaf, generally narrow and long. This is what we observe if we
watch the germination of a grain of wheat.
“A simpler and quicker method may be used for ascertaining how many
cotyledons a seed has. Hold a leaf up to the light and you will see its
texture traversed by a multitude of little cords which serve it as a
kind of framework. These cords are called veins or nerves. Now then, if
you compare the leaf of a pear-tree with a blade of wheat, or reed, you
will see that in the former the veins are more and more subdivided and
ramified, joining one another and thus forming a network with irregular
meshes, while in the latter the veins do not branch, but run in
parallel lines without forming meshes. We should find the same
difference of framework between the leaves of the elm, poplar, and
plane-tree, on the one hand, and those of the iris, narcissus, and
tulip, on the other. This difference being established, I will add that
with few exceptions, of no interest to us here, every plant with
netted-veined leaves has two cotyledons in its seed, and that every
plant with parallel-veined leaves has but one. Consequently it is only
necessary to glance at the foliage in order to know whether the seed
has two cotyledons or only one. I will say further that pines, firs,
and the other resinous trees have as many as ten cotyledons, which show
themselves as a delicate tuft of leaves when the little plant comes out
of the ground.”
Uncle Paul then led the children into the garden to fix in their minds
by observation the lesson they had just learned. “Gather haphazard,”
said he, “the first leaves you come to; then examine them and tell me
how many cotyledons the seed must contain. First, here is the iris,
with large blue flowers and sword-shaped leaves.”
“I see,” said Jules, “veins running in regular lines side by side,
without ever joining one another. Since these veins are parallel the
iris seed has only one cotyledon.”
“And this blade of grass, this also that I pick from a corn-stalk?”
asked his uncle.
“They, too, have parallel veins, both of them; and so their seeds must
have only one cotyledon.”
“And this grape-leaf, this leaf of the cherry tree?”
“It’s my turn now,” Emile hastened to interpose. “The veins form a sort
of lace with very fine meshes. The grape and the cherry have two
cotyledons.”
“It is as easy as that, my friends. The leaf with its arrangement of
veins shows us the fundamental characteristics of the plant. It tells
us whether the germ is fed by one nursing-leaf or two, whether the
young plant comes up with one seminal leaf or two.”
CHAPTER XXIX
GERMINATION
“The germ in the heart of the seed is in a state that may be likened to
deep sleep: its life is, as it were, arrested, suspended. But under the
stimulus of certain conditions it awakens, throws off its coverings,
gathers strength from its stored-up food, unfolds its first leaves, and
appears above ground. This opening of the seed is called germination.
Moisture, warmth, and air are the determining causes; without their
coöperation the seed would remain a certain length of time in good
condition for sowing, after which it would wither and lose its
germinating power.
“No seed germinates without the help of moisture. Water plays a
multiple part. First it soaks into the germ and the parts surrounding
it, causing these to swell more than the envelope, so that the latter,
however hard a shell it may be, is burst open. Through the cracks of
this broken envelope the gemmule pushes out on one side and the radicle
on the other, and henceforth the little plant enjoys the benefit of sun
and air. Germination is more or less slow according to the degree of
resistance offered by the walls of the seed. If these are hard and
stony it is only with extreme slowness that the germ absorbs moisture
and manages to burst its cell. Therefore, to shorten the period of
germination care is taken to thin the shells of excessively hard seeds
by rubbing them with a stone.
“Besides the mechanical part played by water in opening the seed, it
has still another relating to nutrition. The various changes undergone
by the alimentary contents of the perisperm and the cotyledons in
becoming liquefied and capable of absorption cannot take place without
the aid of water. Furthermore, this liquid is indispensable for
dissolving the nutritive ingredients, introducing them into the young
plant, and distributing them evenly throughout. It is plain, then, that
if the seed remains dry it is absolutely impossible for it to
germinate, and that in order to preserve seeds the first condition is
to protect them from moisture.
“With moisture there must also be warmth. As a general rule,
germination proceeds most satisfactorily when the thermometer registers
between ten and twenty degrees centigrade, our spring and autumn
temperature. Outside these limits, be it above or below, germination is
retarded, ceasing altogether in extreme temperatures.
“The coöperation of air is not less necessary. Seeds might have the
proper temperature and sufficient moisture, but if air were lacking
germination would not follow. This capital condition explains to us why
seeds planted too deep fail to come up; why germination is much easier
in soil that is mellow and can be permeated by the air than in soil
that is compact; why delicate seeds should be covered with very little
earth or even simply sown on the surface of the moist ground; and,
finally, why ground on being broken often becomes covered with fresh
vegetation from the sprouting of seeds that have for years lain dormant
in the soil, needing only to be stirred up and brought into contact
with the air in order to germinate.
“Under like conditions of temperature, moisture, and air, by no means
all seeds require the same length of time for germinating. Common
garden cress germinates in about two days. Spinach, turnips, and beans
take three days to come up; lettuce, four; melons and pumpkins, five;
cereals, about a week. Two years and sometimes more are needed by the
rose-bush, the hawthorn, and various stone-fruit trees. Generally seeds
with thick and hard shells are slow in germinating on account of the
obstacle they oppose to the penetration of moisture. Finally, when sown
fresh, immediately after coming to maturity, seeds germinate quicker
than when old, because old seeds have to recover by a prolonged sojourn
in the ground the moisture lost through prolonged drying.
“According to their kind, seeds retain for a longer or shorter period
their power of germinating; but why this vitality is more enduring in
one instance and less so in another, we cannot tell. Neither the bulk
of the seed nor the character of its outside coverings, nor the
presence or absence of a perisperm, appears to decide its longevity.
Such and such a seed lives for whole years, even centuries, while
another loses its germinating power in a few months, from no cause that
we can discover. Thus the seeds of the angelica will not come up unless
they are sown immediately after maturing; but beans have been known to
germinate after being kept more than a hundred years, and rye after a
hundred and forty. Excluded from the air, certain seeds may be kept for
centuries, always ready to germinate whenever favorable conditions
shall present themselves. This explains why strawberry, bluet, and
camomile seeds from ancient tombs have germinated just as new seeds
would have done. Finally, rush seeds have been made to germinate that
were dug up from great depths in the Island of the Seine, the original
site of Paris. Doubtless those seeds dated from the time when Paris,
under the name of Lutetia, consisted of a few mud and reed huts on the
marshy borders of the stream. But despite these remarkable exceptions
let us never forget that recent seed is preferable to old for sowing;
it comes up better and in greater abundance.
“We have just seen that certain seeds are very slow in coming up, as
for example the peach, apricot, and plum, whose thick shells resist the
moisture required for germination. Put directly into the ground in the
very places that the young plants are to occupy later, these seeds
would be exposed to not a few dangers during their leisurely
germination. Prolonged rains might make them rot; various marauders
that are partial to them, such as rats, field-mice, jays, magpies, and
crows, might dig them up and devour them. Besides, they would occupy
for a long time, with no profit to any one, the ground in which they
had been planted. All these objections are avoided by making a
preliminary planting after a method known as stratification, from the
Latin word stratum, meaning bed or layer. In a large, deep earthen pan,
with holes in its bottom, or in any other suitable receptacle, such as
a box, a pot, or a tub, likewise pierced with holes, it is the practice
to place first a layer of small pebbles. The holes at the bottom and
this layer of pebbles are to give easy access to the air and drain off
the excess of water after each irrigation. Next comes a bed of fine
sandy soil, then a layer or stratum of seeds arranged side by side, and
on top of that a second bed of earth. On this is placed another stratum
of seeds, which in its turn is covered with earth; and so the process
goes on with alternating layers of seeds and earth until the receptacle
is full. Then it is watered and placed in a cellar or a dark shed. All
that is necessary after this is to keep the contents of pan or tub
sufficiently moist by an occasional sprinkling. Enclosed thus in a
small space easy to watch over, with no danger from marauding animals,
and without needlessly occupying ground that might be used for other
purposes, the seeds can now take their own time to break their hard
shells and can germinate with all the slowness natural to them.
“When the shells at last crack open and the radicle appears, it is time
to proceed to the final planting. The half-germinated seeds are then
put into the ground one by one in an open field, each at the exact spot
the young plant is to occupy.
“Stratification offers still another advantage. Fruit trees as well as
other trees have a stout tap-root which bores vertically into the
ground to a considerable depth and gives a good deal of trouble if
transplanting is undertaken. To alter this tap-root into a root not
growing so deep, but branching horizontally, would be decidedly
advantageous. In speaking of the root we saw what the nursery-man does
to obtain this result. He passes the sharp edge of his spade under the
base of each tree-trunk so as to sever the tap-roots of his young
plantations. In stratification the method is much simpler and success
surer. With his thumb-nail the gardener nips off the tip of the tender
radicle before the final planting is done. That is all. Deprived of its
growing end the young root henceforth branches out horizontally instead
of descending vertically.”
CHAPTER XXX
THE BLOSSOM
“Here is the fennel-flower, which, with the corn-flower and the poppy,
is so common in our fields of grain. It is purplish red, while the
poppy is scarlet and the corn-flower, or bluet, is of an azure like
that of the sky, as its alternative name indicates. On the outside of
the fennel-flower are five green, firm pieces joined together at the
bottom but terminating in long points at the top. Each of these pieces
is called a sepal, and the five together form the calyx. Inside are
five other pieces, thin, fine, broad, purplish red in color. Each one
bears the name of petal, and collectively they form the corolla.
“Most flowers have two envelopes like these, one within the other. The
outer one, or calyx, is nearly always green in color and firm in
structure; the inner one, or corolla, much more delicate in texture, is
tinged with those magnificent hues that please the eye so much in
flowers.
“The sepals of the calyx and the petals of the corolla are sometimes
separated from one another and sometimes joined together. In the
fennel-flower the sepals are united below in a common sheath bristling
with coarse hairs; but in their upper part they are separated into five
narrow and pointed strips. The corolla we find to be composed of five
pieces, five petals distinct from one another. On the contrary, in the
blossom of the campanula the five petals of the corolla are joined at
the edges and form a beautiful blue bell which looks as if made of one
piece. The five large teeth that border the opening of the bell
nevertheless show that the corolla is really composed of five petals,
of which these teeth are the termination.
“The calyx and the corolla are the flower’s clothing, a double clothing
having both the substantial material that protects from cold and storm,
and the fine fabric that charms the eye. The calyx, the outer garment,
is of simple form, green in color, and of firm texture suitable for
withstanding bad weather. It has to protect the still unopened flower,
to shield it from the sun, from cold and wet. Examine a rose-bud and
note with what delicate precision the five sepals of the calyx are
united so as to cover the rest. Not the slightest drop of water could
penetrate the interior, so carefully are their edges joined together.
There are flowers that close their calyx every evening and snuggle down
inside to keep from getting chilled.
“The corolla or inner garment unites elegance of form and richness of
tint with fineness of texture. It is the flower’s finery and is what
especially captivates our eye, so that we commonly consider it the most
important part of the blossom, whereas it is really nothing but an
ornament.
“Of the two garments, the calyx is the more necessary. Many flowers
have no corolla, but they always have at least a calyx, which in its
simplest form is reduced to a tiny leaflet shaped like a scale. Flowers
with no corolla remain unnoticed, and the plants that bear them seem to
us to have no blossoms. It is a mistake: all trees and plants bloom,
even the oak, willow, poplar, pine, beech, wheat, and multitudes of
others whose blossoming is unheeded by the inattentive eye. Their
flowers are extremely numerous, but as they are very small and have no
bright-colored corolla they escape any but the closest scrutiny.
“It would be knowing a person very little only to be able to say that
he wears such and such a coat; nor does one know a flower any better
when one can merely say that it is clothed with a calyx and a corolla.
What is there under this clothing?
“Let us examine together a lily, which by its size lends itself readily
to study. It has no calyx, [4] but it does have a superb corolla formed
of six petals gracefully curved inward at the edges, and whiter than
ivory. I take away these six petals. What is left now is the essential
part; that is to say, the thing without which the flower could not
perform its function, could not, in short, bear fruit or seed. Let us
carefully consider this remaining part. You will find it well worth the
trouble.
“First there are six filaments or little white rods, each one
surmounted by a tiny bag full of yellow powder. These six pieces are
called stamens. They are found in all flowers in greater or less
number, and in the lily there are six of them. The little bag that tops
the stamen is called an anther. The yellow dust contained in the anther
is called pollen; that is what daubs our nose when we smell the lily
too closely.
“I take away the six stamens. There remains a central body swollen at
the bottom, narrowed at the top to a long filament, and surmounted by a
kind of head wet with a sticky moisture. In its entirety this central
body bears the name of pistil; the swelling at the bottom is called the
ovary, the filament growing out of it is the style, and the sticky head
terminating this filament is known as the stigma.
“What big names for such little things! you will say. Little, yes; but
of unrivaled importance. These little things, my friends, give us our
daily bread; without the miraculous work of these little things the
world would come to an end.
“With a penknife I cut the ovary in two horizontally. In three
compartments grouped in a circle we see some tiny grains arranged so
that each compartment has two rows of them. They are the future seeds
of the plant. The ovary, then, is the part of the plant where the seeds
are formed. After a certain time the flower withers, the petals wilt
and fall, the calyx does the same, or sometimes it remains to play the
part of protector a while longer, the dried stamens break off, and only
the ovary remains, growing larger, ripening, and finally becoming the
fruit that contains the seeds.
“Every sort of fruit—the pear, apple, apricot, peach, walnut, cherry,
melon, grape, almond, chestnut—began by being a little swelling of the
pistil; all those excellent things that the tree and plant give us for
food were first ovaries.”
“Then a big juicy pear began by being the ovary of a pear blossom?”
queried Emile.
“Yes, my friend,” was the reply; “pears, apples, cherries, apricots,
even big melons and enormous pumpkins begin by being the little ovaries
of their respective flowers. I will show you an apricot in its
blossom.”
Uncle Paul took an apricot blossom, opened it with his penknife, and
showed his listeners what is here reproduced in the picture.
“In the heart of the flower,” he explained, “you see the pistil
surrounded by numerous stamens. The head at the top of it is the
stigma; the swelling at the bottom is the ovary or future apricot.”
“That little green thing,” Emile exclaimed incredulously, “would have
turned into a plump, juicy apricot such as I am so fond of?”
“Yes,” affirmed his uncle, “that little green thing would have turned
into an apricot such as Emile is so fond of. A similar little green
thing would have turned into a big juicy pear, into a fragrant apple,
or into a huge pumpkin, so heavy that it rests lazily on its stomach.
To conclude, I will show you the ovary from which come wheat and
consequently bread.”
Uncle Paul took a needle; then with the skill and patience necessary
for this operation he isolated one of the numerous flowers that
collectively make up the ear of wheat. The delicate little flower
displayed clearly, on the point of the needle, the different parts
composing it.
“The blessed plant that gives us bread,” continued Uncle Paul, “has
very modest flowers. Two poor scales serve it for calyx and corolla.
You can easily recognize three hanging stamens with their
double-sacheted anthers full of pollen. The main body of the flower is
the plump ovary which, when ripe, will be a grain of wheat. It is
surmounted by the stigma, which has the shape of an elegant double
plume. Such is the modest little flower that furnishes us all with the
staff of life.”
CHAPTER XXXI
POLLEN
“In a few days, even in a few hours, a flower withers. Petals, calyx,
stamens fade and die. Only one part survives: the ovary, which is to
become fruit. Now, in order to outlive the rest of the flower and
remain on its stem when all else dries up and falls, the ovary at the
moment of blossoming, receives an access of vigor, I might almost say a
new life. The magnificence of the corolla, its sumptuous coloring, its
perfume, all serve to celebrate the solemn moment when this new
vitality is awakened in the ovary. This great act accomplished, the
flower has had its day.
“Well, it is the dust of the stamens, the pollen, that gives this
increase of energy without which the nascent seeds would perish in the
ovary, itself withered. It falls from the stamens on to the stigma,
which constantly wears a sticky coating designed to hold it; and from
the stigma it makes its mysterious influence felt in the very depths of
the ovary. Animated then with new life, the nascent seeds develop
rapidly, while the ovary swells so as to give them the nourishment and
the space they require. The final result of this incomprehensible
travail is the fruit, with its contained seeds all ready to germinate.
“Let us cite a few of the numerous experiments that prove the absolute
indispensability of pollen.
“Most flowers have both stamens and pistils; but there are plants that
have their stamens and pistils in separate flowers. Sometimes the
flowers with stamens only and those with pistils only are found on the
same plant; sometimes they are found on separate plants. Plants having
flowers with stamens only and flowers with pistils only on the same
stock are called monœcious plants. This expression means ‘living in one
house.’ The flowers with stamens and those with pistils do indeed live
together in the same house, since they are found on the same plant. The
pumpkin, cucumber, melon, hazel-nut-tree are monœcious plants.
“Where flowers with stamens and those with pistils are found on
different stocks, the plants are termed diœcious; that is to say, they
are double-house plants. Hemp, the locust-tree, and the date-tree are
diœcious.
“It is especially in monœcious and diœcious plants that the pollen’s
indispensability is plainly manifest on account of the natural
separation of the stamens and pistils. Let us take for example the
locust, a tree of extreme southern France, bearing seeds in pods
similar to those of the pea, but brown, very long, and very wide, and
containing in addition to the seeds a sugary pulp. Supposing we took a
notion, if the climate permitted, to grow locust seeds in our garden,
what locust tree must we plant? Evidently the one with pistils, because
it alone produces the ovaries that become fruit. But that is not
enough. Planted by itself, the locust tree with pistils will indeed
blossom profusely every year, but will never in all eternity bear any
seeds, for its flowers will fall without leaving a single ovary on the
branches. What is wanting? The action of the pollen. Near the locust
with pistils let us plant one with stamens. Now fructification proceeds
as we wish. Puffs of wind, insects that pilfer from one flower and
carry to another—these convey the pollen from the stamens to the
stigmas, the torpid ovaries spring to life, and the locust pods grow
and ripen perfectly. With pollen, seeds; without pollen, no seeds.
“Another example. In spots of fertile land in Northern Africa, spots of
land called oases, the Arabs cultivate numerous date-trees which
provide them with dates, their principal food. Date-trees, too, like
the locust, are diœcious. Now, in the country of the date-tree, a sandy
plain parched by the sun, spots of watered and fertile land are rare
and have to be turned to the utmost possible account. Accordingly the
Arabs plant only date-trees with pistils, the only ones that will
produce dates. But when they are in flower, the Arabs go long distances
to fetch bunches of blossoms with stamens from wild date trees in order
to shake the pollen on the trees they have planted. Without this
precaution there is no harvest.
“But I am coming to an example that will be more familiar to us. The
pumpkin is monœcious: flowers with stamens and flowers with pistils
inhabit the same house, the same vine. Before they are full-blown they
can easily be distinguished from each other. The flowers with pistils
have under the corolla a large swelling which is the ovary, the future
pumpkin. The blossoms with stamens have not this swelling. Well, from
one pumpkin vine standing apart in the garden let us cut off all the
buds with stamens before they open, and leave those with pistils. For
greater surety we will wrap each one of these latter in a piece of
gauze large enough to let the flower develop without hindrance. This
operation must be carried out before the buds open, in order to make
sure that the stigmas have not already received any pollen. Under these
conditions, not being able to receive the vivifying dust, since the
flowers with stamens are cut off, and since also the gauze wrappings
keep out the insects that might bring the pollen they had pilfered from
some neighboring pumpkin vine, the pistillate flowers will wither after
languishing awhile, and their ovaries will dry up without growing into
pumpkins. If, however, we wish any selected blossoms to fructify in
spite of their gauze prison and the suppression of the staminate
blossoms, we take a small camel’s hair brush and gather a little pollen
which we put on the stigma. That is enough, the pumpkin will come.
“The absolute necessity of pollen for the formation of fruit explains
to us the harmful effect of violent winds and prolonged rains in
blossoming time. Swept away by blasts of wind, or washed away by rains,
or simply spoiled by long-continued moisture, the dust of the stamens
no longer acts on the ovaries, and the flowers fall without
fructifying. This ruin of the harvest from lack of pollen is known as
blight.”
CHAPTER XXXII
THE GRAIN OF WHEAT
“Now turn your attention to this picture of an ivy seed cut through
lengthwise. Where is the germ or little plant in its egg? It is that
little white thing, rather long and narrow, embedded in the substance
of the seed at one end. A fine line marks the division of the two
cotyledons, which are now pressed close together. Next to them comes
the tigella, or little stalk, ending in the radicle, or rootlet.
Notice, my friends, how small these cotyledons are, how different from
the enormous nursing-leaves of the almond, acorn, broad bean, kidney
bean, and pea. These poor little plant-udders must soon get dried up,
and if there were no other resources available at the time of
germination the ivy would speedily starve to death.
“But look: under the skin of the seed we find a goodly store of
farinaceous matter, in which the germ is embedded. Almost the whole of
the seed consists of this accumulation of flour. So here we have the
food-supply that will supplement that contained in the cotyledons, a
very insufficient provision in itself. This granary of plenty within
which the germ is lodged, this storehouse of food is called the
perisperm. The almond, acorn, pea, bean, with a host of others, are
quite lacking in anything of the sort, having under the skin only the
germ and nothing more, absolutely nothing. The reason for this
difference is plain enough. The almond, bean, pea, acorn, with their
big cotyledons bursting with nutritive matter, do not need a
supplementary ration; the germ will be sufficiently suckled by the
udders nature has provided in the form of these cotyledons. But the
ivy, with its poor little cotyledons, calls for help, and finds it in
the farinaceous storehouse of the perisperm.
“Thus a seed may have a double supply of nourishment to meet the needs
of the young plant: that contained in the cotyledons and that stored up
in the perisperm. Cotyledons are never lacking, but the perisperm is
not found in all seeds. There is none in the almond, acorn, chestnut,
apricot, bean, or pea; but to make up for this lack their cotyledons
are of considerable size. On the other hand, buckwheat, chickweed, and
ivy, whose cotyledons are small, are provided with a perisperm. All
this may be reduced to one general rule. Cotyledons and perisperm play
similar parts: they both help to nourish the little plant in its
infancy. So, generally speaking, the seed with large cotyledons has no
perisperm, while the seed with small cotyledons has one.
“I have just told you that many plants have only one cotyledon. I will
add that this cotyledon is usually very small. It is especially in
these plants that the perisperm is present. The grain of wheat offers a
notable illustration of this truth. Cut lengthwise and looked at
through a magnifying-glass, this seed would reveal to us what is
represented in the picture I now show you. At the bottom and toward one
side is the germ, forming but a very small part of the seed. At c is
the single cotyledon, whence will come the first leaf, the seminal
leaf. At e is the gemmule, which will furnish the next leaves. At the
opposite end is a short nipple, the radicle, whence the root will
spring. Now compare the tiny cotyledon of the wheat with the two
voluminous ones of the almond. The latter, with their rich store of
nourishment, will easily be able to feed the young plant until it has
vigorous roots; but the cotyledon of the wheat, so poor and slender—can
it nourish the young plant? Certainly not. Then the wheat germ must
without fail have a storehouse of provisions. This storehouse is the
perisperm (pr), a farinaceous mass constituting nearly the whole of the
seed. This same perisperm, the first food of the wheat’s first shoot,
is also the chief food of man; it is what, under the millstone, becomes
flour, of which bread is made. But how can the farinaceous substance of
the perisperm nourish the plant? A very simple experiment will show us.
Put some wheat in a saucer and keep it slightly moist. In a short time
the seed will germinate. As soon as the young sprouts show their green
points take one of the grains: you will find it softened all through.
You can crush it between your fingers and squeeze out a white fluid,
very sweet to the taste and much resembling some sort of milk. What has
taken place ought not to be beyond your power to surmise from the
account I gave you of the wonderful change starch may undergo. The
perisperm of the wheat-grain consists chiefly of starch. During
germination this accumulation of starch is converted into a sugary
substance, into glucose in fact. Thence comes the sort of plant-milk
with which the seed is now swollen. The germ is immersed in this sweet
liquid; it imbibes it, soaks it up almost as a fine sponge would; and
with the matter thus absorbed it augments its own substance, which
lengthens into root, stem, and leaves. With what furnishes us bread the
grain of wheat suckles the starting wheat-stalk.”
CHAPTER XXXIII
CULTIVATED PLANTS
“Three modes of plant-propagation are in use among horticulturists,
namely: layering, slipping, and grafting. To get an adequate notion of
the great usefulness of these operations let us dwell for a moment on
the origin of our cultivated plants.
“You perhaps imagine that from the beginning of time, in view of our
need of food, the pear-tree was eager to bear large fruit, plump and
juicy; that the potato, just to accommodate us, stuffed its big tubers
with farinaceous matter; that the cabbage, in its desire to gratify us,
conceived the idea of gathering those beautiful white leaves into a
compact head. You imagine that wheat, pumpkins, carrots, grapes, beets,
and no one knows what besides, possessed with a great interest in man,
have always worked for him of their own accord. You think that our
grapes of to-day are like those from which Noah extracted the juice
that made him drunk; that wheat, ever since it appeared on the earth,
has never failed to yield its annual harvest of grain; that the beet
and the pumpkin had at the beginning of the world the plumpness that
makes them prized by us now. You imagine, in short, that our
food-plants came to us originally just as we have them now. Undeceive
yourselves: the wild plant is usually of very little nutritive value to
man. His is still the task of so cultivating it as to derive advantage
from its natural aptitudes by improving them.
“In its native country, on the mountains of Chile and Peru, the potato
in its wild state is a poor diminutive tuber about as large as a
hazel-nut. Man takes the worthless wild stock into his garden, plants
it in rich soil, tends it, waters it; and behold, from year to year the
potato thrives more and more, gaining in size and in nutritive
properties, and finally becoming a farinaceous tuber as large as your
two fists.
“On the sea-coasts, exposed to all the winds that blow, there grows a
wild cabbage with a tall stalk and a few green leaves of bitter taste
and rank odor. But beneath its rude exterior it may perhaps hide
invaluable aptitudes. Apparently this suspicion occurred to him who
first, so long ago that the record of it is lost, took the sea-coast
cabbage under cultivation. The suspicion was well-founded. The wild
cabbage has been improved by man’s incessant care: its stalk has become
firmer and its leaves have multiplied, whitened, acquired tenderness,
and massed themselves in a compact head, so that we have the crisp and
succulent cabbage of to-day as the admirable result of this notable
metamorphosis. There on the sea-coast rock was the first beginning of
the excellent plant; here in our gardens is its present attainment. But
what about its intermediate forms which, through the centuries, marked
the gradual development of the species to its present high state of
perfection? Each of these forms was a step forward, and each had to be
preserved, kept from degenerating, and made the subject of still
further improvement. Who could tell the story of all the labor and
pains it has taken to produce the cabbage-head as we now have it?
“And the wild pear-tree—are you acquainted with it? It is a frightful
bramble-bush, all bristling with sharp thorns; and the pears
themselves—a most repellent fruit, sure to choke you and set your teeth
on edge—are very small, sour, hard, and full of grit that reminds one
of gravel-stones. Surely he must have had an extraordinary inspiration
who first pinned his faith on this crabbed specimen of underbrush and
foresaw in the remote future the butter-pear on which we regale
ourselves to-day.
“In the same way, by the painstaking culture of the primitive vine,
whose grapes were no larger than our elderberries, man has, in the
sweat of his brow, developed the luscious fruit of the modern vineyard.
From some poor species of grass now forgotten he has also produced the
wheat that to-day supplies us with bread. A few wretched herbs and
shrubs, far from promising in appearance, he has cultivated and
improved until they became the vegetables and fruit trees so prized by
us at present. This old earth of ours, in order to make us work and
thus fulfill the law of our existence, has behaved to us like a harsh
stepmother. To the birds of the air she gives food in abundance, but to
us she offers of her own free will nothing but wild blackberries and
sour sloes. But let us not complain, for the stern struggle with
necessity is precisely what constitutes our grandeur.
“It is for us, by our intelligence and labor, to work our way out of
the difficulty; upon us it is enjoined to put into practice the noble
creed, God helps those who help themselves.
“Thus from the earliest times it has been man’s study to select from
the countless forms of vegetation at his disposal those that best lend
themselves to improvement. The greater number of species have remained
useless to us, but others, predestined no doubt, and created especially
with a view to man’s needs, have responded to our efforts and acquired
through cultivation qualities of prime importance, since our sustenance
depends on them. Nevertheless the improvement attained is not so
radical that we can count on its permanence if our vigilance relaxes.
The plant always tends to revert to its primitive state. For example,
let the gardener leave the headed cabbage to itself without
fertilizing, watering, or cultivating it; let him leave the seeds to
germinate by chance wherever the wind blows them, and the cabbage will
quickly part with its compact head of white leaves and resume the loose
green leaves of its wild ancestors. In like manner the vine, set free
from man’s constant attention, will degenerate into the little-esteemed
wild species that haunts our hedge-rows and yields a scant harvest that
will not, all together, be worth a single bunch of cultivated grapes.
The pear-tree, if neglected, will again be found on the outskirts of
our woods, once more bristling with long sharp thorns and bearing
under-sized and extremely unpalatable fruit. Under like conditions the
plum-tree and the cherry-tree will bear nothing but stones covered with
a sour skin. In short, all the riches of our orchards will in similar
circumstances undergo such deterioration as to be worthless to us.
“This reversion to the wild state occurs even under cultivation and in
spite of efforts to prevent it when seed is used for propagating the
plant. Suppose the seeds from an excellent pear are put into the
ground. Well, the trees that spring from those seeds will bear for the
most part only mediocre or poor, even very poor, pears. Another
planting is made with the pits of the second generation, and the result
shows still further decline. Thus if the experiment is continued with
seeds taken each time from the immediately preceding generation, the
fruit, becoming smaller and smaller, bitterer and harder, will at last
return to the sorry wild pear of the thicket.
“One more example. What flower equals the rose in nobleness of
carriage, in perfume and brilliant coloring? Suppose we plant the seeds
of this superb flower; its descendants will turn out to be miserable
bushes, nothing but wild roses like those of our hedges. But we need
not be surprised at this. The noble plant had the wild rose for
ancestor, and in trying to propagate it by its seed we have simply
caused it to resume its native characteristics.
“With some plants, let us note in conclusion, the improvement attained
by cultivation is more stable and persists even when the seed is used
for purposes of propagation; but this persistence is only on the
express condition that our vigilance shall not relax. All plants, if
left to themselves and propagated by seed, revert to the primitive
state after a certain number of generations in which the
characteristics imposed by human skill and care gradually disappear.”
CHAPTER XXXIV
DIFFERENT WAYS OF PROPAGATING
“Since our fruit-trees and ornamental plants, if propagated by seed,
revert sooner or later to the wild type, how can they be propagated
without risk of degeneration? This must be done by means of the buds
instead of the seeds. Buds or branches of a plant or tree must be
transplanted from one stock to another; this is called grafting; or
they may be planted directly in the soil by processes known as layering
and slipping. These are invaluable methods, since they enable us to
stabilize in the plant the improvements attained after long years of
labor, and thus to profit by these improvements, which we owe to our
predecessors, instead of beginning all over again a course of training
that would demand far more than a single life-time.
“Layering, slipping, and grafting insure the faithful reproduction of
all the qualities of the parent stock. As are the fruit, flowers,
foliage of this parent stock which has furnished the buds or slips for
transplanting, so will be the fruit, flowers, foliage of the resulting
plant or tree. Nothing will be added to the qualities we wish to
perpetuate, but on the other hand nothing will be subtracted. To the
double flowers of the original from which came the layer, the slip, or
the graft, will correspond the double flowers of the plant developing
from this layer, slip, or graft: the same shade of coloring will be
reproduced, and the fruit will have the same size, savor, and
sweetness. The slightest peculiarity which, for unknown reasons,
appears in a plant grown from the seed, and which sometimes is found
only on a single branch, as the indented outline of the leaves or the
variegation of the blossoms, is reproduced with minute accuracy if the
graft, slip, or layer is taken from the branch having this
modification. By this means horticulture is daily enriching itself with
double flowers or a new shade, or with fruit remarkable for its size,
its early or late ripening, its juicy flesh, its more pronounced aroma.
Without the help of graft and slip these fortunate accidents, occurring
but once and no one knows how, would lead to no further profit after
the death of the plant thus favored by chance; and horticulture would
find itself compelled to repeat over and over again its attempts to
bring about improvements which, almost as soon as effected, would
invariably be lost for want of means to fix them and render them
permanent.
“If history had preserved the record, what long and painful efforts to
develop our various cultivated plants from worthless seedlings should
we not read there! Just think of what a happy inspiration it must have
taken to select exactly the kind of vegetable or other plant
susceptible of improvement, what patient experimental attempts to
subject it to cultivation, what wearisome labor to improve its quality
from one year to another, what care to prevent its degenerating and to
hand it down to posterity in perfect condition. Think of all this and
you will see how the smallest fruit, the smallest vegetable, represents
more than the toil of him who has raised it in his garden. It
represents, perhaps, the accumulated effort of a hundred generations,
an effort indispensable if we are to have a succulent pot-herb as the
descendant of a worthless weed. We live on the fruit and vegetables
created by our predecessors; we live on the labor, strength, ideas of
the past. May the future in its turn live on our strength both of arm
and thought! So shall we worthily fulfill our mission.
“It was not chance that gave man the idea of layering, slipping, and
grafting, but rather the thoughtful observation of nature’s methods all
about him. He who was first, for example, to note how the strawberry
grows and multiplies, received the first lesson in layering. Let us in
our turn examine this curious process.
“From the parent stock of the strawberry vine a number of runners start
out, long, slender, and creeping on the ground. These runners are also
known as stolons or creeping suckers. After reaching a certain distance
they expand at the end into a little tuft which takes root in the
ground and is soon self-supporting. The new tuft of the strawberry
vine, as soon as strong enough, in its turn sends out long runners
which follow the example of the first ones; that is to say, they creep
along the ground, end each in a rosette of leaves, and take root. The
picture shows us a first tuft, more vigorous than the others. From the
axil of one of its leaves starts a runner whose terminal bud has
developed into a small plant already provided with roots of some vigor.
A second runner sprung from this plant bears a third rosette whose
leaves are beginning to unfold. After sending out an indefinite number
of similar runners the mother plant finds herself surrounded with young
suckers, established here and there, as many as the season and the
nature of the soil permit. At first these suckers are attached to the
mother plant by the runners, and sap flows from the old plant to the
young ones; but sooner or later there is a severance of ties, the
runners dry up and are henceforward useless, and each offshoot,
properly rooted, becomes a separate strawberry vine. Here we find,
without any of man’s ingenuity or skill, all the details of layering;
and it was undoubtedly the natural process that suggested the
artificial method. A long branch bends down to the ground, takes root
there, and then becomes detached from the parent stock by the death or
destruction of the connecting part. The horticulturist lays a long
shoot in the ground, waits until it sends down adventitious roots, and
finally severs the connection with his pruning-shears. That is
layering.”
CHAPTER XXXV
LAYERING
“Some plants, and among them the pink, send out from the base of the
mother stalk straight, pliant shoots which can be used for obtaining so
many new plants. These shoots are bedded by being bent elbow-wise and
having the angle stuck into the ground and fastened there with a
crotch; then the end is raised upright and held so by means of a stake.
Sooner or later the buried elbow sends down adventitious roots, but
until then nourishment is drawn from the parent stock. When the buried
parts have sent down enough roots, the connections are cut between the
old plant and the new ones, and each of these latter, set out by
itself, is thenceforth a distinct plant. This operation is called
layering, and the several shoots used in obtaining new plants are
called layers.
“Let us now put into practice the method we have just been studying in
theory. In a vineyard, we will suppose, a number of the vines have died
from some cause or other, and it is necessary to replace them. Layering
offers us the readiest means and will occasion least delay to the
harvest. Near the place occupied by the dead vine we select a stock
provided with a vigorous shoot of sufficient length and conveniently
situated. Then we dig down where the old vine stands and pull up all of
the lifeless stalk as well as the roots, since these are seats of decay
that might infect the whole neighborhood. Finally, in the soil thus
stirred we dig a ditch two or three decimeters deep, and in this we lay
the shoot we have selected, taking care in bending it down not to break
or splinter it. The part thus put into the ground is then covered with
a tolerably thick layer of earth, and on this, to complete the filling
of the ditch, is thrown a basketful of manure. The tip of the shoot is
raised upright, tied to a stake, and trimmed in such a manner as to
retain only two eyes or buds above ground. As to the eyes on the part
extending from the mother stem to the point where the shoot plunges
into the ground, they are nipped off because they would needlessly
appropriate a part of the sap. This operation is called vine-layering,
and the shoot bent down and placed in the ground we speak of as a
vine-layer. The best time for this work is the beginning of winter,
because the long rest enjoyed by the shoot in the ground throughout the
season when vegetation slumbers disposes it to sprout with more vigor
upon the renewal of sap-circulation in the spring.
“Let us now watch the behavior of the partly buried vine-shoot. If it
had remained all in the open air, it would have borne fruit; it would
have had its three or four bunches of grapes. Why should it not do so
under the conditions imposed by the vine-dresser, conditions that have
altered nothing in its relations to the mother stem? It still remains
in uninterrupted communication with the vine that sustains it; it
receives its share of ascending sap drawn from the soil by the roots of
this vine; the buds remaining to it will develop leaves which, with the
help of sunlight, will convert this crude sap into elaborated sap; in
short, it lacks nothing to enable it to function almost as it would
have done had it not been partly buried. And in fact the vine-layer
does bear that same year; if well cared for, it bears several bunches
of grapes. So the proverb says: The vine-layer pays its owner from the
very first year. Meanwhile, acted on by the coolness and moisture of
the soil and the stimulus of fertilization, it puts forth adventitious
roots where it has been placed underground, and these roots grow in
number and vigor until the time comes when they suffice to nourish the
young vine without the help of the mother stem. It is in the third year
that the rooting is far enough advanced for the young offshoot’s
independent existence. Weaning is then undertaken, and the nursling is
deprived of its nurse; that is to say, a stroke of the pruning-knife
close to the ground and on the side toward the parent stock separates
the latter from the vine-layer, which becomes henceforth
self-supporting.
“With its long shoots so near the ground the vine offers every
convenience for carrying out the operation just described; but as a
general rule shrubs and trees are far less favorably situated: their
branches are not long enough or flexible enough or (a prime essential)
near enough to the ground to be bent down and laid in the trench dug
for receiving the layer. How is this difficulty to be overcome? The way
is very simple. We have already observed the effect of cutting back; we
know that a stem cut back, that is to say cut off close to the ground,
develops around the border of its wound numerous adventitious buds
which grow into so many shoots. They are precisely the sort of shoots
we need, long, flexible, and starting from the level of the ground.
Each of them, if treated as a layer, partly buried in a trench where it
is fixed with a crotch, and held, above ground, in a vertical position
by means of a prop, takes root sooner or later according to its
species, and can then be transferred as an independent plant to any
desired spot. Such is the simple method known both as layering and as
arching, because it is essentially the same as ordinary layering and at
the same time necessitates the bending of the young shoot so as to
describe an arch.
“The following method dispenses with this bending, which is
impracticable when the wood is too brittle. In the spring the stalk or
trunk that is to furnish the layers is cut back. All around this
cross-section young shoots soon make their appearance, after which it
is only necessary to wait until they are long enough but have not yet
lost their tenderness, a state most conducive to the growth of
adventitious buds; then the parent trunk is earthed up, or in other
words light soil is heaped all about the stump so as to cover the lower
part of each shoot. The earth is piled up in the shape of a truncated
cone with a cup-shaped hollow at the top to receive water from time to
time and thus maintain the necessary degree of moisture and coolness.
Kept damp and cool in this manner, the young shoots will before long
send down adventitious roots, and the following year there will be a
cluster of rooted plants that can easily be detached with a knife. That
is what is called layering by earthing up or by sprouting.
“If it is found undesirable to cut back the parent stem in order to
obtain shoots for layering, and if at the same time the shoot that we
wish to root is too high to be bent down and inserted in the ground,
the following expedient may be employed. A flower-pot broken in two
lengthwise or a leaden cornucopia is hung on the tree, and the branch
to be rooted is placed lengthwise in the pot or cornucopia. The pot is
then filled with mold or moss kept damp by frequent watering, and the
result, sooner or later, is the growth of adventitious roots. When
these are suitably developed, gradual weaning is next in order; that is
to say, underneath the pot a slight cut is made, and this is deepened
day by day. The end here in view is to accustom the layer little by
little to do without the mother stem and support itself. At last the
separation is complete. This gradual weaning is no less advantageous
when the layers are placed in the ground: it assures the success of the
operation.
“If the wood is tender, adventitious roots spring without difficulty
from the interred part, and the methods already described suffice for
the success of the layering; but woods of dense structure are more or
less obstinate about taking root, and might remain in the ground
indefinitely without yielding. In such cases our art must intervene,
based on the plant’s manner of living. Let us recall the effect of a
band drawn tightly about a stalk or trunk. Above this line of
strangulation the descending sap accumulates more and more, since it
can no longer continue on its course between the wood and the bark,
this latter being compressed by the ligature. It accumulates and
produces a ring-shaped swelling where the plant tries to discharge on
the outside the superabundance of matter arrested in its passage. Let
this protuberance be heaped about with fresh earth, and adventitious
roots will speedily be developed to allow the sap to continue its
descent. A tiny streamlet, running free, follows its channel without
effort and without any undermining of obstacles. But if we obstruct its
passage the accumulating body of water will gain power to open new
vents for itself through the dam. Sap does likewise. Circulating freely
in its natural channel, it is not diverted from its course by any
allurements on its way; and unless the conditions present in wood and
bark favor the growth of new roots, no sap will be expended for this
purpose. But if its usual passage is barred, the sap devotes its
energies to the formation of adventitious roots in order that it may,
through them, resume its interrupted course. A like result follows if a
ring of bark is removed from the buried part of the branch or shoot
that we wish to take root. The arrested sap produces a ring-shaped
swelling on the upper edge of the wound, and from this swelling spring
roots.
“Now let us apply these theoretical principles. If the wood is compact
and for that reason rebels against the laws of simple layering, we will
take a piece of wire and strangle (that is the word) the branch we are
operating upon; that is to say, we will bind it tight, but without
breaking the bark. The compression should be made just below a bud or
eye, and about midway of the part that is to be underground. This
process is called layering by strangulation.
“Or again, still midway of the part to be bedded in the earth, and
immediately under a bud, we cut the bark all around the branch without
injuring the wood; a second incision is made a centimeter and a half
lower down; then tearing off the strip of bark between the two
circumcisions, we remove it all in one piece. This method is known as
annular incision from the ring of bark thus taken away.
“Or as a third expedient, still midway of the part to be bedded in the
trench, we make with a sharp instrument an oblique incision from below
upward, cutting into the wood as far as the marrow. In this way we are
enabled to raise a tongue comprising half the thickness of the shoot,
and this tongue is held in its lifted position by a small pebble
inserted in the slit. This is what we call a Y-shaped incision, because
the raised tongue forms with the rest of the stem an opening like that
between the two branches of the letter Y. Through the half that remains
intact communication with the mother stem is maintained and the needed
share of crude sap is received, while from the cut and upraised half
adventitious roots are put forth because the course of the descending
sap is arrested there.
“In order to bring into contact with the damp soil a greater extent of
wounded fiber fit for putting forth adventitious roots, it is customary
to split the upraised tongue in two and keep the two parts gaping by
interposing a small pebble. This method of double incision is used for
trees that offer the greatest resistance to successful layering.
“To sum up, all these methods and others derived from them have for
their object the fostering of adventitious roots by arresting the
course of the descending sap at a certain point beneath the soil.”
CHAPTER XXXVI
SLIPPING
“Propagation by means of a slip or scion cut from the parent tree and
so placed that it will develop adventitious roots we may for
convenience speak of as slipping. The cut end of the slip is set in the
ground in some cool, moist, shady spot where evaporation is slow and
the temperature mild. For delicate slips the shelter of a bell-glass is
often necessary in order to insure the requisite moisture in the
atmosphere and thus prevent the slip from drying up before it has sent
down roots to make good its losses. For greater surety, if the slip has
many leaves, most of the lower ones are removed in order to reduce the
evaporating surface as much as possible without compromising the
plant’s vitality, which resides especially in the upper part. But in
many cases these precautions are needless; thus, to propagate the
grape-vine, willow, and poplar, it suffices merely to thrust the
detached scion into the ground.
“Trees whose wood is soft and well filled with sap are the ones best
fitted for slipping; to this class belongs the willow, with its notably
tender fiber. On the other hand, wood that is dense and hard gives us
sure warning that this mode of propagation will be found very difficult
or even impossible. Thus it would invariably fail with the oak, the
olive, the box-tree, and a great many more hard-wood trees.
Furthermore, slipping offers far less certainty of success than
layering, since the layer remains in communication with the parent
stock and is thus supplied with nourishment until it has acquired roots
of its own, whereas the slip, all such communication being abruptly cut
off, is obliged from the outset to rely on its own resources and pass
without help through the difficult period of rootlessness. Among
fruit-bearers there are scarcely any except the grape-vine, the
currant-bush, the quince-tree, and a few varieties of plum and apple
trees, that lend themselves to this method of propagation. Among the
larger trees the willow and the poplar take root with no difficulty
whatever when started from the slip. Finally, a great many ornamental
species, herbaceous plants or bushes like the rose, jasmine, and
honeysuckle, multiply easily by this method, the usual one adopted with
them by the flower-gardener.
“Let us go back now to the very simplest case, the one calling for the
fewest precautions. A damp piece of ground on the water’s edge is to be
planted with poplars or willows. Toward the end of winter the forester
in charge cuts a sufficient number of vigorous young branches as large
around as a stout cane or even a man’s fist, or perhaps larger, and
from one to four meters long. He removes all the lower twigs, clips the
intermediate ones to half their length, and leaves the upper ones
intact if the tree is to be pyramid-shaped; otherwise he gives the top
a truncate form. Finally the lower end is cut to a point with the
hatchet, to make it easier to thrust into the ground. Now the slip is
ready for planting, and all that is necessary is to push it well down
into the earth by its pointed end and leave it to itself. Without any
further attention, if the ground is sufficiently damp, adventitious
roots will start, and each of the stakes thus rudely hacked will become
a poplar or a willow.
“But other forms of vegetation are far from manifesting this facility
in rooting which makes possible the growth of a tree from a stake
driven into the ground, it may be with the blow of a club; therefore
delicate precautions are necessary for success if these obdurate
subjects are to be propagated by slips. Let us take the grape-vine as
an example. Its slips for planting are shoots of the same year’s
growth. These are tied in a bundle and their cut ends placed in water
to soak for a week or more. Why this long immersion of the part that
later is to be planted in the ground? Because the outside bark is dry
and tough, difficult for tender roots to pierce, especially if the soil
is dry. Accordingly the bark is softened by soaking for some time in
water; and also, when the slips are taken out of the water, they are
lightly scraped where they are to be in the earth, but left untouched
where they are to be in the air. In this way the outer layer of bark is
removed after being softened in water, and there is so much the less
resistance offered to the growing roots; but the inner layers, where
the vine’s vital activities go on, are scrupulously spared. The slight
wounds inflicted by this scraping, let it be further noted, favor the
starting of roots by arresting the sap. After being prepared in this
manner the slips are set out. In soil that has been well worked so that
the young roots may push downward without hindrance, vertical holes are
made with a long iron or wooden dibble, and in each of these holes a
slip is inserted to the depth of about half a meter. Fine earth is then
sifted into the hole and well rammed down to insure perfect contact
with the slip, and the operation is finished.
“Just as the process of layering is facilitated by the formation of a
ring-shaped swelling where the descending sap is arrested in its course
either by a ligature or by the removal of a ring of bark, so the same
artifice can be advantageously employed in propagating by means of
slips. Around the shoot selected as slip for the next year’s planting
an iron wire is tightly bound; or, instead of this, a ring of bark is
cut away. By autumn a swelling will have formed all about the stem,
whereupon the shoot is detached and placed in the ground for the winter
in order that the swelling may become a little further enlarged and
somewhat softened. In the spring the shoot is taken up again, trimmed
so that it shall have only four or five buds left, and planted like an
ordinary slip. From the ring-shaped swelling caused by the accumulation
of sap roots will start.
“All the advantages offered by the ring-shaped swelling may be secured
with no expenditure of ingenuity on our part. Take hold of a small
branch and pull it down so as to split it off from the main stem. Thus
torn away it will bring with it a sort of spur or splinter from the
trunk directly under the severed branch. This spur, trimmed with a
knife to give it a less ragged outline, will render the same service as
the ring-shaped swelling: the descending sap will be stopped in its
course at this point, will accumulate, and will foster the growth of
adventitious roots.
“Instead of breaking off the branch by tearing it away at its base, one
can, with a stroke of the pruning-knife above this base and another
below it, cut the older limb bearing this branch so that the latter
carries with it a piece of the former. With this piece as a sort of
natural bourrelet or swelling, success is rendered more assured than in
any other way.
“To conclude, let us say a few words about slipping by means of buds, a
kind of planting that uses buds instead of seeds. This method, which
requires the nicest care of any, is adopted only in exceptional cases.
Let us suppose we have a very few shoots, or only one, from some
extremely rare variety of grape-vine, and we wish to obtain from this
single shoot the greatest possible number of slips. To this end the
shoot is cut into small pieces about five centimeters long, each
bearing a bud midway of its length. These pieces are then each split in
two lengthwise, and the part with the bud is retained, the other thrown
away. Thus prepared, the pieces are planted in fertile soil with the
split surface underneath and the bud just peeping out of the earth. But
to insure any likelihood of success with this method, certain special
conditions not called for in ordinary planting must be observed, as
will be readily understood. The delicate slips are arranged with care
in an earthen pan or pot, and covered with a bell-glass to assure them
a moist and warm atmosphere. After roots have started the slips are
transplanted, each being placed in a separate pot where it gains
strength and awaits the proper time for planting in the ground.”
CHAPTER XXXVII
GRAFTING
“Grafting is the process by which a twig or a bud [5] is transplanted
from one branch to another, or from one tree to another. That which is
to serve as support and sustenance to the transferred part is known as
the stock, while the twig or bud received by it is called the graft.
“One absolutely necessary condition must be fulfilled if this operation
is to be successful: the transferred part must find on its new
nursing-branch nutriment to its taste, that is to say, a sap like its
own. This requires that the two plants, the stock and the one that
furnishes the graft, should be of the same species or at least belong
to closely related species, since likeness of sap and its products can
result only from likeness of organization. It would be a mere waste of
time to try to engraft the lilac upon the rose, or the rose upon the
willow, for there is nothing in common between these three species
either in leaves, flowers, or fruit. This difference in structure is
invariably accompanied by a marked difference in respect to nutrition.
Hence the rose-bud would starve to death on a lilac-branch, and the
lilac-bud would meet with the same sad fate on a rose-bush. But lilac
can very well be grafted on lilac, rose-bush on rose-bush, vine on
vine. And one can even go further than this: a peach-bud will flourish
on an apricot-tree, a cherry-bud on a plum-tree, and vice versa; for
between the members of each of these pairs there is a close and easily
discernible analogy. In short, there must be the closest possible
resemblance between the two plants if grafting is to succeed.
“The ancients were far from having any clear idea on this absolute need
of likeness in organization. They tell us of grafting the holly with
the rose to obtain green roses, the walnut tree with the grape to
produce enormous grapes as large as walnuts. In our own time has not
the project been seriously considered of grafting a vine shoot on to a
mulberry tree in order to restore vigor to the grape whose roots an
underground grub has attacked? Such graftings and others between plants
completely unlike have never been successfully undertaken except in the
imagination of those who dreamt them.
“We have already seen that, grown from seed, our various fruit trees do
not, as a rule, reproduce the quality of fruit of the parent stock; an
invincible tendency to revert to the wild state causes the fruit to
lose, little by little, from one generation to another, the improvement
it had acquired through cultivation. Thus the pear, through repeated
plantings of the seed, would become increasingly sour, small, and hard,
until it had at last returned to the sorry state of the wild pear
growing on the edge of the woods. But this defect attending growth from
the seed is redeemed by one very desirable quality: the tree thus grown
regains more or less the robustness of its wild type; it is
incomparably more vigorous, healthier, longer-lived, than the
artificially perfected tree whose strength is compromised by the very
excess of its fructification. One has vigor, the other fine fruit. The
two attributes cannot go together; if one increases, the other
decreases. Well then, these robust specimens reared from the seed are
just what we require for grafting. Used as stocks, they supply the
quality inherent in them, namely, vigor; and the cutting engrafted upon
them furnishes the other quality, excellence of fruit.
“Accordingly it is the practice to plant the pips of pears and apples,
and the stones of apricots and peaches; and on the trees thus obtained
to graft cuttings from pear, apple, apricot, and peach trees that bear
fruit of recognized superiority. In this way there are united in the
same tree the root and trunk of the robust and almost wild kind with
the leaves and blossoms of the weak but artificially improved kind.
Every variety of pear tree is by nature fitted to receive a pear graft,
every variety of peach tree to receive a peach graft, and so on with
all fruit-trees. There is no objection to selecting as stock any wild
pear, cherry, or plum tree that may have sprung up of itself in hedge
or thicket. It is thus for example that the cherry is grafted on two
others of like sort, the wild cherry and the cherry of Saint Lucia,
both frequenters of uncultivated hillsides. The first bears fruit
hardly as large as a pea, black, round, and full of a very dark and
rather bitter juice; the second has still smaller fruit with scarcely
any pulp and uneatable. No matter: with grafts from a suitably chosen
source they will cover themselves with the finest cherries. In like
manner our superb garden roses can be grown on the wild rose stock, the
common dog rose of the hedges, whose modest blossoms have only five
petals of a pale carnation color and are well-nigh odorless. Sometimes,
again, two species of similar characteristics are chosen for grafting
purposes. Thus the pear grafts well on the quince-tree, the fruit of
the latter being, after all, a sort of big pear; the apricot can be
grafted on the plum; the peach on the plum and, still better, on the
almond, so like the peach in its foliage, its early blossoming, and the
structure of its fruit.
“As a curiosity let us mention the mixing of several kinds of fruit on
the same stock. By means of grafting the same tree can bear, all at one
time, almonds, apricots, peaches, plums, and cherries, because these
five kinds admit of reciprocal grafting; another tree may be covered
simultaneously with pears, quinces, berries of the mountain ash,
medlars, and service-berries. These are very odd instances, certainly,
but of no practical interest. It would be a waste of time to dwell
longer on them did they not teach a useful lesson. They demonstrate
that however many fresh grafts are added to a tree, the new-comers
exert no influence outside their own sphere. Whether offshoots of the
tree itself or aliens, the grafts develop, blossom, and fructify, each
after its own kind, without contracting any of its neighbor’s habits.
Among the curious phenomena observed in this artificial juxtaposition
of mutually independent grafts, we will mention a pear-tree on which
were represented, by means of grafting, all the different varieties of
cultivated pears. Sour or sweet, dry or juicy, large or small, green or
bright-colored, round or long, hard or mellow, each and all ripened on
the same tree and grew again year after year without change, faithful
to the specific character, not of the supporting tree, but of the
various grafts planted on this common stock.
“The mere bringing together of analogous plants does not suffice for
the success of the operation of grafting; there must be a considerable
extent of contact between those parts of the graft and the stock that
have the most vitality and are consequently best fitted to coalesce.
This contact should be in the inner layers of the bark and in the seat
of plant-growth situated between the wood and the bark. The vital
activity of the plant, in fact, resides especially in this region. It
is between the wood and the bark that the elaborated sap descends;
there is where new cells and new fibers are organized, to form on one
side a sheet of bark and on the other a layer of wood. Hence it is
there and only there that coalescence is possible between the graft and
the stock.”
CHAPTER XXXVIII
GRAFTING
(Continued)
“There are three principal kinds of grafting, namely: grafting by
approach (also called simply ‘approaching’ or ‘inarching’), grafting by
shoots or scions, and grafting by buds (commonly known as ‘budding’).
The form given to the two cut ends that are brought together and the
disposition of the parts thus placed in contact give rise, in practice,
to numerous subdivisions that need not be mentioned here. We will
confine ourselves to the essentials.
“Grafting by approach is analogous to layering, with this difference,
that the tree to be grafted takes the place of the soil that receives
the layer. In layering we induce the growth of adventitious roots by
partly burying in the ground a branch or shoot still adhering to the
stock that nourishes it. When, acted upon by the soil, roots have
started in sufficient number, the shoot is gradually cut loose until at
last it is quite severed from the parent stock. In grafting by approach
it is also proposed to make a branch, a shoot, a tree-top, while still
united to its own stem or stock, take root, so to speak, not in the
ground, but in the substance of a neighboring tree.
“Let us suppose that two shrubs are growing close together and that we
wish to engraft on one of them a twig or shoot of the other. The parts
to be placed in contact receive each a longitudinal gash that
penetrates to the marrow, or even deeper, and the two gashes are made
of equal length. These parts are then brought together, care being
taken to make the young and growing portions in the one exactly meet
those in the other; that is to say, the inner layer of bark in each,
with the channel traversed by the elaborated sap, is carefully fitted
to the corresponding part in its neighbor. The whole is thereupon made
fast with a ligature, and the two wounds are left to the slow operation
of vital forces. Fed by its own stem or trunk, from which it is not yet
separated, the shoot to be transplanted mingles its sap with the sap of
its neighbor; on both sides there are new growths to cicatrize the
wounds, while the two parts gradually coalesce until, sooner or later,
the graft becomes incorporated with its future support. And now the
graft must be weaned; that is, it must, little by little, be deprived
of the sustenance furnished by its own stock. This is accomplished as
in simple layering, by gradually cutting through the shoot below the
point of union. As soon as the graft is thought to be getting all its
nourishment from the new stem, it is completely severed from the mother
tree. This mode of grafting, the most elementary of all, sometimes
takes place accidentally and unassisted. In a hedge or any dense growth
of bushes, if two branches chance to come into close and prolonged
contact, there will be at this point, first, a slight abrasion and then
a complete wearing away of the bark until the two raw surfaces end, it
may be, in growing together. It is not improbable that natural
occurrences of this kind furnished man with his first notions of
grafting.
“Grafting by approach is an excellent method to apply whenever in the
arrangement of a fruit-tree’s branches there is a vacant space that
needs filling. Regular distribution, symmetry of arrangement, is a
condition demanded if only to satisfy the eye, which is always offended
by disorder; but there is another and still more convincing reason for
this regularity. The more evenly a tree’s branches are distributed, so
that each shall receive an equal share of sap, sunlight, and heat, so
much the more fruit will it bear. Suppose, then, there is a lack of
branches in some part. To fill this gap and thus restore the tree’s
symmetry, grafting by approach offers a ready means. From a branch near
the vacant space and itself sufficiently supplied with twigs or shoots,
one of these latter, of good length, is selected; then it is properly
cut or gashed and the gash is brought into contact with a similar gash
at the point where it is desired to start a new growth; and, finally, a
ligature is applied to hold the two parts together. As soon as
coalescence is complete the graft is severed below the point of union,
and the lower section, after being straightened up again, is ready to
serve once more as branch to the limb that bears it. In this way, with
no loss to themselves, the more abundant branches furnish offshoots to
the poorer ones.
“Grafting by means of shoots or scions cut from the parent stock at the
outset is analogous to slipping. It consists in transplanting on to a
new stock a shoot detached from its mother branch. The most common
method is cleft-grafting. It is done in the spring when the buds begin
to open. Shoots of the preceding year are chosen for grafts, care being
taken to select those that are vigorous and that have attained no later
than August the hard and woody condition necessary for resistance to
the severities of winter. One precaution at the very outset must be
taken. When the graft is put in place it will be of the utmost
importance that it shall find in its new position nourishment
proportionate to its needs. It would infallibly perish if it should
prove to be in a more advanced state of vegetation than the stock
selected to nourish it. The latter, therefore, ought to be rather ahead
of than behind the former in this respect. To secure this result,
between one and two months before the operation is to be carried out it
is well to cut the grafts and place them in the ground on the north
side of a wall, where they will remain quiescent while the branches to
which they are to be transferred will make progress and their sap will
start.
“We will suppose there is a worthless pear-tree in our garden, grown
from a pip or transplanted from its native wood, and we propose to make
it bear good pears. The course to pursue is as follows. We cut off
entirely the upper part of the wild pear tree, trimming the cut with
our pruning-knife so that there are no ragged edges, since these would
not scar over readily and might become the seat of a far-reaching
decay. If the trunk is of moderate size and is to receive but one
graft, it is cut a little obliquely with a small level surface on the
upper edge, as shown in the picture. In the middle of this horizontal
facet a split is made to the depth of about six centimeters. That done,
we take one of the grafts set aside as already indicated, and we cut it
so as to leave only two or three buds, of which the topmost one should
be at the tip of the branch. Then, just under the lowest bud we whittle
the end of the graft into the shape of a knife-blade, letting the bud
stand just above the back or dull edge of the blade. For greater
stability when the graft is put in place, a narrow inverted ledge is
cut at the top of the blade on both sides. A glance at the picture will
show you all these little details. Finally, the graft is slipped into
the cleft of the stock, bark exactly meeting bark, wood meeting wood.
The whole is brought tightly together by binding, and the wounds are
covered with grafting mastic, which may be bought already prepared. If
this mastic is lacking we can use what is known in the country as Saint
Fiacre’s ointment, a sort of paste made of clay, or rather a mixture of
clay and cows’ dung, the fibrous nature of the latter preventing the
former from cracking. A winding of rags holds the ointment in place.
Thus wound, the stump does not suffer from exposure to the air, which
would dry it up. In course of time the wounds cicatrize, and the bark
and wood of the graft coalesce with the bark and wood of the severed
trunk. Finally the buds of the graft, nourished by the stock, develop
into branches and at the end of a few years the top of the wild pear
tree is replaced by that of a cultivated pear tree bearing pears equal
to those of the tree that furnished the graft.
“The operation of cutting back a branch or trunk to receive the graft
always promotes the growth of numerous buds. What is to be done with
the shoots that spring from these? Evidently they must be suppressed,
for they would appropriate, to no good end, the sap intended for the
graft. Nevertheless the suppression must be done cautiously. Let us not
forget that what primarily causes the sap to ascend is the evaporation
of moisture from the leaves. As long as the graft has not opened its
buds and spread its leaves, it is well to let the young shoots of the
stock remain untouched. They act as helpers, in that their foliage
draws upward the juices extracted from the soil by the roots; so that,
far from having an injurious effect at this time, their presence is
most useful. But the day will come when the graft alone will suffice
for this work of pumping up the sap, and then it is best to get rid of
these messmates which, of heartier appetite than the graft, would soon
starve it out. First the lower shoots of the stock are suppressed, then
gradually those higher up, care being taken not to destroy the top ones
until the graft has developed shoots two or three decimeters long.”
CHAPTER XXXIX
GRAFTING
(Concluded)
“The part of a plant or tree above ground and the part under ground are
mutually dependent, the development of one implying a corresponding
development in the other. If there is a superabundance of foliage, the
roots will be unable to furnish it sufficient nourishment; on the other
hand, if the roots are unduly vigorous, there will be too much sap for
the foliage—an excess of nourishment which, there being no use for it,
will encumber the plant and be injurious to it. Hence if the trunk to
be grafted is strong it must have several grafts, in order that the
number of buds to be nourished may be in right proportion to the number
of nourishing roots.
“To this end the trunk is cut, not obliquely as for a single graft, but
horizontally. Then it is split all the way across, following a line
that passes through the central pith, and two grafts are implanted in
the cleft, one at each end. It is evident that not more than two can be
placed in the same cleft, because the bark of the graft must of
necessity come in contact with the bark of the stock to insure
inter-communication and coalescence between the sap-canals of the two.
If the size of the stock requires more than two grafts, instead of
splitting the trunk diametrically several times, it is preferable to
make lateral clefts which, leaving the center untouched, cause less
danger to the solidity of the stock.
“Recourse can also be had to the following method, in which no clefts
whatever are called for, clefts being difficult to cicatrize when the
wood is old. The grafts are cut like the mouthpiece of a flute; that is
to say, at the base half is taken off lengthwise while the other half
is left, but is whittled down, thinner and thinner toward the end, much
like a flute’s mouthpiece. Thus shaped, the grafts are inserted between
the wood and the bark of the stock, an operation facilitated by the
flow of sap in the spring, when the bark separates easily from the
wood. If there is danger of tearing the bark under the strain of the
graft acting as a wedge, a slight incision is made in the bark to give
it the play it needs. In this way the circumference of the stock
receives the number of grafts deemed necessary. It only remains now to
bind the whole securely and cover the wounds with mastic. This method
is called crown-grafting, because the grafts are arranged in a crown on
the circumference of the cross-section.
“Grafting by buds corresponds to that variety of slipping in which
buds, each one by itself on a small fragment of the branch, are set
into the ground. It consists in transplanting on the stock a simple bud
with the bit of bark that bears it. It is the method most commonly
employed. According to the time of year when the operation is
undertaken, the graft is called an active bud or a dormant bud. In the
first case the grafting is done in the spring, when nature is awaking
from her winter’s sleep, so that the eye or bud implanted in the stock
coalesces with it and very soon develops into a young shoot. In the
second instance the bud is set in place some time in July or August, at
the period of the autumnal sap, so that it lies dormant or, in other
words, remains stationary during the following autumn and winter, after
uniting with the stock.
“The implement here required is the grafting-knife, furnished at one
end with a very sharp blade, and at the other with a short spatula of
bone or very hard wood. The first thing to do is to remove the bud to
be transplanted. On a branch in which the sap is working we make with
the grafting-knife a transverse cut above the bud and another below;
then, holding the branch in one hand and the grafting-knife in the
other, as the picture shows, we remove the strip of bark lying between
these two cuts and delimited laterally by the line gg´g´´ and its
opposite, in figure F. This strip, which we call the shield, is shown
by itself in H. The leaf that sheltered the bud in its axil has been
removed, but the base of the stem of this leaf has been left and will
be useful later for taking hold of the shield and handling it more
conveniently. The shield must be cut away without any tearing and in
such a manner that no sap-wood is left clinging to the bark. The latter
must be perfectly intact, especially in its inner layers, the seat of
vital activities. Finally, the bud should have its proper complement of
young, greenish wood, which constitutes the germ, the very heart of the
bud. Should this germ be removed by unskilful manipulation, the bud
would have to be thrown away, for the graft would surely fail.
“The next step is to make a double incision in the bark in the shape of
a T, penetrating as far as the wood but without injuring it. With the
spatula of the grafting-knife the two lips of the wound are raised a
little while the bud with its shield is taken up by the piece of
leaf-stem attached to it and inserted between the bark and the wood.
All that now remains to be done is to draw the lips of the little wound
together and bind the whole with some sort of material sufficiently
pliant and elastic not to compress and finally strangle the bud as it
develops. A rush, a slender thong made of a long and flexible
grass-blade, or, better still, a piece of woolen yarn is well suited to
the purpose. But if despite all precautions the ligature should after a
while prove too tight on account of the swelling of the graft, it would
be necessary to loosen it without delay. As soon as the graft has
‘taken,’ as we say, the young shoots starting out on the stock are
gradually suppressed in the cautious manner prescribed for
cleft-grafting.
“When the stock is too small to receive a bud in the usual manner, the
following expedient is resorted to. From a shoot of about the same size
as the stock a rectangular strip of bark with bud attached is cut with
four incisions of the grafting-knife. This strip is immediately laid
upon the stock to serve as a pattern while the point of the knife is
passed all around it. In this way there is cut from the stock a strip
of bark having exactly the same shape and size as the pattern, which
latter is thereupon inserted in the vacant place and made fast there by
a ligature. This process may not inappropriately be called veneering.
“In flute-grafting the bark both above and below the bud is cut
transversely all around the stem, and then another cut is made
lengthwise between these two slashes. A cylinder of bark may thus be
peeled off in one piece. From the stock, which should match this
cylinder in size, a similar cylinder is removed and its place taken by
the other one bearing the bud we wish to transplant.”
CHAPTER XL
ROTATION OF CROPS
They are eating dinner at the farm. A large platter of pork cutlets and
beans is smoking in the center of the table. Every one has been served.
It is a pleasure to see these good people eat, they have such hearty
appetites. Jacques, the big ox-driver, is the first to finish. He
throws his bone away. Azor is there to seize it. He lies flat on his
stomach and takes the bone in his fore paws. Hear him bite on his hard
pittance. How it cracks! Let any one beware of teasing Azor now. An
angry growl and a baring of his four formidable canine teeth would warn
the rash intruder to have done with his joking at once, for if
not—well, I will not be responsible for the consequences. Azor is not a
surly dog; far from it; but he is well within his rights when he brooks
no nonsense at his meals. He has done his duty most valiantly as a dog.
Night before last some wolves were prowling about the sheep-fold, and
he drove them off. Let Azor gnaw his bone in peace.
Ha, there! The big tortoise-shell cat, Master Minet, is otherwise
minded. He draws near, hair erect, tail as large around as your arm, to
try to frighten Azor and rob him of his allowance. Azor, without
dropping the bone, gives a low growl and lifts one paw. That is enough,
the cat flees. So, my bold Minet, what were you after here? The bone is
not for you; your teeth are not strong enough to bite it. Go away!
Martha is calling you to give you some bread soaked in gravy. That will
suit you better than a bone as hard as a stone.
Ah, here come some more guests. The door stands open and in come the
hens from the poultry-yard. Tap, tap, tap, tap; they peck the crumbs
fallen from the table. Azor has no use for such diet—tiny morsels much
too small for him; nor does the cat want them either, they are too
floury. But the hens feast on them.
And all, human beings, dog, cat, hens, dine at the same time; only each
must make the best of what the others cannot use. Azor is content with
the bone that big Jacques threw away; the cat is satisfied with a
little bread soaked in gravy, a dish quite inadequate to Azor’s needs;
the hens pick up the crumbs disdained by Jacques, Azor, and the cat.
Martha, it seems, had prepared dinner only for the farm people, and
behold, by utilizing the scraps that are worthless to some, many others
join in the midday meal. From the scraps disdained by man the dog will
gain strength to defend the flock; from those rejected by the dog the
cat will acquire keen eyesight and sharp claws to see and to seize the
mouse; from what is of no value to the cat the hens will make eggs; and
everything, absolutely everything, will go to the profit of the farm.
“Agriculture in its turn,” remarked Uncle Paul, turning to account this
homely illustration in domestic economy, “prepares dinner for the crops
in its own peculiar manner. It spreads the ground with manure, that
fertile dressing so relished by growing plants. The table is set, or in
other words the field is ready, well plowed and harrowed, and well
manured. Whom shall we call first to the table, for it is plain we
cannot invite all at once. Whom shall we call first? It shall be wheat,
let us say, a plant with tastes hard to please, but one that in return
gives us bread. So wheat is sown. In this soil, full of all sorts of
good things, it cannot fail to thrive, however unfavorable the season
may be. It will select what suits it best and leave the rest.
“Now that is done. The harvest is in, and it handsomely comes up to our
hopes. The wheat has converted into magnificent grain the fertilizer
put into the ground. Out of decay it has created nourishment. Surely it
has well acquitted itself of its charge. It has made a clean sweep: all
that could be turned into wheat it has appropriated, and there remains
nothing further to be done. What would happen, then, if wheat were sown
again in the same field? Exactly the same thing that would happen to
Simon if he had nothing to eat but the bone that Jacques threw away. He
would die of hunger. Simon must have man’s food, wheat must have
wheat’s food. So if the first crop has exhausted the supply of material
for making wheat, how can you expect to raise a second crop? Evidently
that is asking the impossible; it is running the risk of reaping only a
very mediocre harvest or even none at all. Therefore it is the rule not
to sow wheat twice in succession in the same field. And what is true of
wheat is true also of all other crops. Where a plant has prospered one
year, the same plant will not do well the second year, because the
ingredients required by this plant are more or less exhausted. It is
foolish to invite guests to a table that is stripped bare.
“If the table were spread again, if more fertilizer were added to the
soil, that would be quite a different matter, and wheat would grow as
well as it did the first time. But such a procedure would be bad
management, for the very utmost should be made of one meal. Before
further expenditure in the way of fertilizer let us exhaust the virtue
of the fertilizer already applied. Azor dined well on what Jacques
discarded; the hens were well fed with what Azor and the cat left. Let
us take an example from this succession of eaters who utilize each in
his own way the remnants worthless to the others. The wheat has
exhausted, or nearly exhausted, all that is suitable for wheat; but
just as Jacques the ox-driver left the bone, it has left in the soil a
good many ingredients that make excellent food for other crops. In
order, therefore, to utilize to the last ounce the first spreading of
fertilizer, we must invite to the repast a guest of different tastes.
This guest may be, for example, the potato. In soil that would have
furnished but starvation diet for wheat the potato will find quite
enough to live on, its tastes not being the same as the cereal’s.
“Thus we have two successive crops for one coating of manure: we have
sacks of potatoes with no additional outlay in fertilizer. Is that all?
Not yet. After the wheat and the potatoes there is, to be sure, but
meager nourishment left in the upper layer of the soil; but in the
lower layers there remains the part of the fertilizer that the rain has
washed down and dissolved and that the short roots of the preceding
crops could not reach. To utilize this underlying matter and bring it
up again to the surface in the form of forage let us now sow a plant
with vigorous roots, such as clover, sainfoin, or, still better,
lucerne, which will penetrate deeper. And so we get our third crop.
“After clover we can try a fourth crop, of a different kind; but it is
evident that as the guests succeed one another at the same table the
remnants become more and more scanty and difficult to utilize.
Accordingly we must choose a hardy plant and one that is content with
little. Finally a time will come, and at no very distant date, when the
board will be bare: the coating of manure will have given up its last
particle of nutritious matter. Then the table must be garnished afresh,
the field fertilized anew before beginning again with the same crops or
attempting others. Let us demand no more. You understand, my young
friends, that in order to utilize to the utmost this precious substance
that gives us every kind of food, such as bread, vegetables, forage,
meat, fruit, dairy products—to make the very best use of this we must,
instead of raising the same crop in the same field year after year,
adopt the plan of varying our crops, changing from one of one kind to
another of a different character, so that what earlier plantings have
left in the soil may be turned to account by later ones. This
succession of different sorts of farm produce is called rotation of
crops.”
CHAPTER XLI
ROTATION OF CROPS
(Continued)
“When soil is spoken of as worn out and needing rest, the speaker uses
a figure of speech meaning that the soil has been exhausted by the
crops it has borne. The crops do indeed take from the land a great
quantity of substances necessary for plant-life; and when these
substances are no longer present in sufficient amount, the soil refuses
to produce; it is exhausted. To restore its original fertility would
require a large outlay in fertilizer and hence it is often more
advantageous to accomplish this object by one of the following methods.
“Sometimes the land is allowed to lie fallow; that is to say, it is
left to itself without any care whatever for whole years. Weeds spring
up freely, and at the same time water, air, and frost act on the soil,
disintegrating and mellowing it and inducing the formation of certain
substances necessary to vegetation. The weeds are converted into mold,
and finally the land, rested and recuperated, is ready to bear a new
crop. Restoration by this process is very slow, taking several years,
and hence it is customary to shorten the period of waiting by working
the soil and even manuring it, although it may not yet be the intention
to sow any seed. In these circumstances the land is called fallow land.
“There is, however, one way to obtain an uninterrupted succession of
crops from the same land unless the soil is very poor. All plants
derive their nourishment from the soil and the atmosphere; but some
take more from the atmosphere, others from the soil. The plants that
get their sustenance chiefly from the air are those that have luxuriant
foliage. The potato is one of these. You know that it is through their
leaves that plants obtain the carbonic acid gas diffused in the air.
The greater the spread of foliage, the more abundant will this
absorption be. The plants that depend almost wholly on the soil are
those with only a few small, slender leaves, thus taking but little
carbonic acid gas from the air. Such is wheat.
“Moreover, from the potato plant we take only the tubers, which form
but a small part of the whole, and we turn under the stalks and leaves,
which are thereupon converted into humus. Thus the potato has the
property of enriching the soil at the expense of the atmosphere, and it
gives back more than it takes. It is, then, one of the enriching rather
than impoverishing plants in respect to its action on the soil.
Cereals, on the contrary, are utilized by the harvester both as to seed
and haulm, nothing but the meager roots being left in the ground; and
as, on account of their very scanty foliage, cereals derive almost
their entire sustenance from the soil, they take from it much more than
they give back to it. They accordingly belong to the class of plants
that impoverish rather than enrich the soil in which they grow.
“It is impossible, thus, except by a ruinous expenditure of fertilizer,
to raise a crop of grain every year on the same land. But if we should
let potatoes succeed wheat, and wheat succeed potatoes, what would be
the result? The latter crop, deriving a large part of its nourishment
from the air, would flourish in soil comparatively exhausted by wheat;
and on having its leaves and stalks turned under it would give back to
the soil a part of its former fertility. Wheat could then be
successfully raised again on the same land.
“This practice of raising successively on the same land different crops
as little harmful to one another as possible and capable of utilizing
to the utmost the dressing put on to the land, is nothing but that very
rotation of crops that I have already told you something about. Its
purpose is to economize fertilizer and at the same time to secure an
uninterrupted succession of crops. The underlying principle consists in
making an enriching plant succeed an impoverishing one; that is to say,
a plant with luxuriant foliage is made to succeed one with scanty
foliage. The chief enriching plants are clover, lucerne, sainfoin,
potatoes, turnips, and beets. Cereals, on the contrary, are all
impoverishing plants. It is a general custom to raise on the same land
a more or less extended series of different crops, the series running
four, five, or six years, or even longer, after which it begins over
again in the same order. This rotation of crops is designated according
to the number of years the series covers, as for instance a five-year
or a six-year rotation. A six-year rotation might run, we will say,
somewhat as follows:
1st year—potatoes—enriching crop.
2nd year—wheat—impoverishing crop.
3rd year—clover—enriching crop.
4th year—wheat—impoverishing crop.
5th year—sainfoin—enriching crop.
6th year—oats—impoverishing crop.
“Let us examine in detail this series that we have taken as an example.
The first year the soil is thoroughly manured. One of the effects of
manuring is to start a great crop of weeds that would infest the land
and impoverish the crop were they not carefully removed. Hence the
necessity of weeding. To weed a piece of ground is to destroy the weeds
either by hand or with some implement. But it is not every crop that
admits of weeding: the plants must be a certain distance apart, as
otherwise they will be trampled under foot, cut off, or uprooted in the
weeding process. Wheat cannot be weeded, its stalks are too close
together; but potatoes are far enough apart for weeding without
difficulty. Now, weeding destroys all useless, injurious grasses and
other unwelcome intruders; their future reappearance is prevented by
pulling them up before their seeds ripen, and thus at last the ground
is cleaned and made ready for a choice crop. This will explain to you
the great advantage of letting the potato or some other crop that can
be weeded take precedence of the cereals.
“The second year comes wheat. Cleaned by the tillage that has gone
before, the ground is no longer covered with grass and weeds. Nor does
it need fresh manure, for if the potatoes have consumed certain
elements in the soil, these are not exactly the same that wheat
requires; and, furthermore, the dead plants, turned under and reduced
to vegetable mold, compensate by what they have derived from the
atmosphere for what the tubers may have taken from the soil. Wheat is
therefore just the crop to raise now.
“But it would be much against one’s interest to exact from the soil
another crop of wheat the third year. Exhausted by the grain it has
just produced, the soil would yield but a scanty harvest unless it were
freshly manured, a process that would make of the whole operation, not
a piece of farming, but an example of gardening, and would also entail
too great expense. For that reason the third year is devoted to the
raising of an enriching crop, such as clover. After furnishing a supply
of fodder, what is left of the clover is turned under, and all its
remnants of roots, stems, and leaves are reduced to mold, which renders
the soil fit for another wheat harvest the fourth year. A third
enriching crop to be turned under after the final mowing, is likewise
needed for the fifth year; and this crop may be sainfoin. At the end of
the series comes another cereal, oats, for example. The rotation is now
complete, and the program begins all over again.
“Crop-rotation is capable of innumerable variations, and the series may
be longer or shorter, but there should be the slightest possible
departure from the rule that a cereal crop ought always to be preceded
by some crop that enriches the soil.”
CHAPTER XLII
LAND-DRAINAGE
“In the bottom of a flower-pot you will find a small round hole. Over
this hole it is customary to lay a bit of broken tile, and on this, if
the plant to occupy the pot is delicate, a few small pebbles. This
done, the pot is filled with vegetable mold. Why this hole, this bit of
tile, these pebbles? That is what we are now about to consider.
“Water is absolutely indispensable to plants, since it is the medium
that dissolves the various nutritive ingredients of the soil and thus
renders them capable of assimilation by the roots. Accordingly the soil
penetrated by these roots must be constantly supplied with sufficient
moisture either by rainfall or by artificial irrigation. But air is not
less indispensable. It disinfects the soil and by causing slow
combustion of the humus gives rise to a slight but uninterrupted
liberation of carbonic acid gas, one of the nutritive substances
required by vegetation. Should the roots be cut off from this
life-giving agency, they would languish and finally decay. Thus it is
that if vegetation is to thrive the soil in which it grows must have at
the same time both air and water. But if the bottom of the flower-pot
has no opening, or if its opening is stopped up, the water from the
watering-can will not flow through, nor will there be any air admitted
from below, and for lack of this the roots will decay. On the other
hand, if the water, after saturating the earth, runs out freely by the
hole in the bottom of the pot, the damp soil will become a sort of
sponge to which the air will have access from all sides, and the plant
will thrive.
“This reasoning applies to the most extensive agricultural operations
as well as to the care of a potted plant. After water has soaked into
the ground it should find some channel to carry it off; otherwise the
roots will decay for want of air. That is why clayey soils, which
retain water when they are once saturated, are unsuited to agriculture,
while light soils, having sand mixed with the clay and thus readily
allowing the water to drain off, are well adapted to it. For the same
reason, again, a sandy subsoil accelerates vegetation, and a clayey
subsoil retards it. A sandy subsoil offers the same advantage as a
flower-pot open at the bottom, whereas a clayey subsoil is like a
flower-pot closed at the bottom. In the first case the surplus of water
drains off and the air has free access; in the second the superabundant
moisture finds no outlet and the air cannot reach the roots.
“Now let us suppose we have a marshy soil to deal with. Because of the
stagnant water either on the surface or a little below it nothing can
grow on this piece of ground except rushes or other hardy plants
designed by nature for this kind of soil. Accordingly we proceed to dig
a number of small ditches, of a depth somewhat greater than that
attained by plant-roots, and we fill the bottom of these ditches with
small stones, on which we finally throw back the earth we have removed.
These underground ditches are suitably inclined, and all empty at the
lower end into a main canal. The water saturating the soil collects in
these ditches, filters through the layer of pebbles, and empties into
the main canal, which carries it off to some river or other stream. Our
marshy soil is now like the potful of earth with a hole at the bottom,
the bit of broken tile, and layer of little pebbles: the air has free
access and brings fertility with it. This operation of ours is called
drainage, a word formed from ‘drain,’ which is both a verb and a noun.
In the latter sense we apply it to the narrow ditch dug for carrying
off superfluous water.
“A drainage system like that just described is the simplest possible,
but there is one serious objection to it: the layer of small stones
soon becomes clogged with soil washed down by the water, and the latter
can no longer run off. Hence it is customary to use fagots instead of
stones, since they offer less obstruction. But still better results are
obtained with earthenware conduits laid in the ditches. Sometimes these
conduits take the form of drain-tiles such as are used on roofs, and
they rest on sills or ground-pieces of the same material; or, again,
they may be tubular in form, the successive sections loosely fitted
together so that the water to be carried off may enter where the
sections join.
“The effect of drainage is not merely to carry off the superfluous
water and thus promote the aëration of the soil to the depth reached by
the roots; it also keeps the soil cool and moist by the constant
presence of water in the drainage ditches or pipes. When a heap of sand
is watered at its base, the moisture is seen to mount higher and higher
until it reaches the top. In like manner the water collected in our
drainage ditches soaks into the upper soil in a dry time and thus
reaches the roots of plants growing there, so that water which is
superfluous or even harmful at certain periods is held in reserve and
gradually distributed at the right moment.
“Another advantage of a drainage system is that it prevents that
cooling of the soil which would result from prolonged evaporation. In
taking the form of vapor water chills the objects that help to promote
the evaporation. For this reason we feel a decided chill on emerging
from a bath; the film of moisture that covered us is passing off in
vaporous form. Similarly a constant evaporation at the surface of a
water-soaked tract of land chills the ground and we have a cold soil.
But if the water is carried off by proper drainage, evaporation ceases
and there is no further chilling of the surface soil. Now, a high
temperature is always favorable to vegetation.
“Draining is so beneficial that it is not confined to marshy ground,
which without it would be quite unproductive, but is applied also to
ordinary arable land. Wherever the soil is too clayey, or even where
the surface soil is good but the subsoil clayey, rain-water cannot
drain off readily and the ground remains soggy and cold. Eventually,
however, it dries up, but there being no way for the air to permeate
the soil, the latter is left hard and unyielding, so that the roots are
by turns drowned in liquid mud and held fast in a tenacious paste that
has been baked by the sun. Drainage overcomes these difficulties, and
consequently all rich soils that hold rain-water for some time before
infiltration are much improved by being properly drained.”
CHAPTER XLIII
PARING AND BURNING
“You see that man over there on the hillside,” said Uncle Paul,
pointing to a laborer who, with a large hoe, was paring the ground, so
to speak, by shaving off great squares of earth covered with grass and
weeds and shrubs. “You see how he stands those pieces up, either in
pairs, back to back, or one at a time, so bent or vaulted that they
will stay upright by themselves. Thus the air is allowed to circulate
and dry them rapidly. If we come back in a few days, after sun and air
have done their work and the drying process is complete, we shall find
our man there again at his work; and we shall see how he piles up the
turf with the earthy side upward and outward. In the middle of the pile
he leaves a cavity which he fills with brushwood and dry leaves. Then
he sets fire to the whole. A second pile is constructed in the same
manner and likewise set on fire. Soon the entire hillside is covered
with a great number of these small furnaces, burning slowly and sending
out long trails of smoke. In a few days, three or four at most, the
fires burn themselves out, and then, as soon as all the piles are cold,
the mixture of ashes and calcined earth is spread over the ground with
a shovel. This agricultural operation is known as paring and burning,
and is carried out for the purpose of rendering arable a tract of land
not yet under cultivation and still covered with wild vegetation.
“The operation of paring and burning produces two effects, one with
reference to the clay in the soil, the other having to do with the
ashes left from the burning of the weeds. Clay, as you know, is a
tenacious, binding substance, impervious to both air and water.
Consequently a soil that is too clayey is unfavorable for vegetation,
furnishing the roots with insufficient air and moisture. Now, when clay
is heated to a high temperature, it acquires very different properties:
it no longer makes paste by the addition of water, but is porous,
permeable, and readily admits air and water. The paring-and-burning
process, therefore, improves an argillaceous soil by calcining the clay
and rendering it permeable. That is as much as to say that if paring
and burning are beneficial to heavy or clayey soils, they are, on the
other hand, harmful to those that are light or sandy.
“Finally, the operation just described affects the soil through the
ashes of the burnt weeds. After the combustion of all vegetable matter
there remains an earthy powder or ash comprising the mineral substances
contained in that vegetable matter, substances unchanged by combustion
because of their great resistance to heat. The most important of these
is potash. All the ingredients that once belonged to the burnt plants
are evidently adapted to the formation of new plants. The ashes, then,
of the weeds consumed in the process of paring and burning will be very
useful to the plants about to be raised on the land that has been burnt
over. By the burning, however, it is impossible to turn to account all
that the weeds contained: what escapes in the form of smoke is so much
lost. Hence care should be taken not to carry combustion too far. In
this connection the calcined clay renders still another service. By
becoming porous through calcination its nature is altered so that it
can absorb and retain the gaseous products of combustion and thus save
just so much waste. But if a soil lacks clay, paring and burning are
harmful, and it is better simply to turn the weeds under, whereupon
they will be converted into mold instead of being dissipated in the
atmosphere as smoke.
“Ashes other than those resulting from paring and burning are also used
as an agricultural fertilizer, though they are rarely put to this use
just as they are, because the contained potash, a highly valuable
substance, is first extracted by leaching. After this process the ashes
are called buck-ashes. They contain silica and also carbonate and
phosphate of lime, all in a condition most favorable for assimilation
by plants. Of less strength than ordinary ashes, leached ashes
nevertheless produce good results, especially on clayey soil. Coal
ashes, too, it should be added, serve to lighten a heavy soil since
they contain a large proportion of calcined clay.
“The subject of ashes leads us naturally to that of soot, a substance
composed of vegetable matter incompletely decomposed by heat and
containing ammonia, which renders it highly efficacious as a
fertilizer. It is applied to young plants, giving them an increased
vigor of growth. By its acrid quality, moreover, it is excellent as a
protection against insects that attack vegetation.”
CHAPTER XLIV
WINE-MAKING
“When wine is heated, there is first an escape of an inflammable vapor
that burns with a bluish flame. A person needs only to have seen once
this preparation of hot wine to recall that curious flame flickering
over the boiling liquid and darting up little blue tongues. Now, this
inflammable vapor comes from alcohol, a fluid substance that gives to
wine its peculiar properties and is hence sometimes called spirits of
wine. There are, then, in wine two distinct liquids, one easily
reducible to vapor and called alcohol, the other slower to vaporize and
recognizable as water. This does not mean that the wine has been
watered: the water in question is not there as the result of fraud; it
belongs naturally to the wine and comes from grapes just as alcohol
does. Wine is therefore a natural mixture of a small proportion of
alcohol with a great quantity of water. In our ordinary wines the
proportion of alcohol for each hundred quarts of liquid varies from
nine to fourteen quarts.
“Wine is made from the juice of grapes. This juice, as it is pressed
out of the sweet grapes, has none of the taste or smell peculiar to
wine, for it does not yet contain any alcohol; but it does have an
agreeably sweet taste, the same taste that makes grapes so desirable a
fruit for the table. This pleasant flavor is due to a sort of sugar
present in the grapes. Examine carefully a handful of raisins such as
you buy at the grocer’s: you will detect on their surface, certain tiny
white grains that crunch under the teeth and have a sweet savor. Those
grains are little particles of sugar that have collected on the outside
of the grapes during the process of drying. Grapes, then, must contain
sugar.
“Well now, this sugar is exactly what causes the formation of alcohol.
What is sugar in the fresh juice of grapes is alcohol in the same juice
after it has fermented and turned to wine. Let us consider briefly how
this change comes about.
“The vintage is first of all subjected to a process of treading by men
who trample on the grapes in large vats, after which the resulting
mixture of juice and skins is left to ‘work,’ as we say. Before long
this liquid mush begins to heat of its own accord, and presently there
sets in a sort of boiling which liberates big bubbles of gas as if
there were a fire underneath. This working process is called
fermentation, and its seat is in the sugar of the grape-juice. Little
by little the sugar decomposes, splits apart as we might say, into two
substances very different from each other and also very different from
the sugar whence they came. Of these two substances one is alcohol; the
other is a gas already known to us—carbonic acid, the same gas that
plants feed on and that animals give forth in breathing; the same,
finally, as that produced by burning coal. The alcohol remains in the
liquid, which thus gradually loses its original sweet taste and
acquires instead a vinous flavor. The gas, on the contrary, works its
way to the surface, agitating the mass with a sort of tumultuous
movement like that of boiling water, and is dissipated in the
atmosphere.
“Let us bear in mind that carbonic acid gas is as invisible as the air
itself, that it has no odor, no color, and finally that it kills
quickly if inhaled in any considerable quantity. That explains the
danger lurking in a wine-vat during fermentation, or even in a
wine-cellar that lacks sufficient ventilation to carry off the perilous
gas. No one should enter such places without holding before one a
lighted taper at the end of a long stick. While the taper continues to
burn in the usual manner, one can proceed without fear: there is no
carbonic acid gas present. But if the flame becomes dim, gets smaller
and smaller, and finally goes out altogether, one must beat a hasty
retreat, for the extinction of the taper is a sure sign of the presence
of carbonic acid gas, and further advance would mean exposing oneself
to imminent death.
“But to return to the subject of wine-making, we were saying that the
sugar which imparts its sweet taste to the must (that is, the
unfermented grape-juice) changes its nature and divides into two parts:
alcohol, which remains in the liquid and turns it to wine, and carbonic
acid gas, which is dissipated in the atmosphere. When this process is
finished the wine is drawn off, leaving behind the residuum of skins
and pips. The final product is thus composed of a large quantity of
water from the grapes themselves, a small quantity of alcohol from the
sugar which has undergone the chemical change just described, and,
finally, a coloring substance furnished by the dark grape-skins.
“White wine is made from white grapes, which have skins with no
coloring matter; but it can very well be made from dark grapes, colored
though they are. The secret consists simply in this: the crushed grapes
are pressed before fermentation begins. In this way the juice is
separated from the skins, and, these latter being removed, the wine
will be white even with dark grapes. In short, the coloring matter in
grapes which gives its hue to red wine is contained solely in the
skins; and furthermore it is insoluble in water, but easily soluble in
alcohol. Hence it is only after fermentation has made some progress
that the liquid becomes colored by the dissolving of the coloring
matter through the agency of the alcohol that has been generated.
Accordingly, if the skins are removed before the juice ferments and
generates alcohol, the wine remains white, since it no longer contains
any coloring matter to dissolve.
“Some wines force out the corks from their bottles and are covered with
foam on being poured into glasses. These are foamy wines, and to
produce them the bottling must be done before fermentation is finished.
The carbonic acid gas then continues to form, but as it finds no way of
escape since the bottle is tightly corked, it dissolves in the liquid
and accumulates there, though all the while endeavoring to free itself;
and that is what makes the cork pop with a sharp report when the string
that holds it down is cut; that is what causes the wine to rush foaming
out of the bottle; and, finally, that is what gives the bead to a glass
of wine and makes a slight crackling sound as the bubbles burst on the
surface.
“Foamy wine has a pungent but agreeable taste owing to the carbonic
acid it contains. We drink, dispersed through the liquid, the same gas
as would kill us if freely inhaled; but it has no terrors except when
thus inhaled. Mixed with our drinks, it imparts to them a slightly tart
flavor, harmless and even salubrious, since it aids digestion. There is
carbonic acid gas in nearly all water that we drink, and it is in fact
by reason of this gas that water is able to hold in solution the small
proportion of stony matter that contributes toward the formation of our
bones. It is to this gas, finally, that effervescent lemonade, cider,
beer, and Seltzer water owe their pungency and their foam.”
CHAPTER XLV
THE STAG-BEETLE
“One of the joys of your time of life, I am sure,” resumed Uncle Paul,
as he and his hearers seated themselves in the shade of an old oak tree
amid the humming and whirring of insect life all about them, “is the
study of the little creatures of field and farm and forest, so
interesting in their mode of life, so varied in their forms and colors.
You chase the splendid butterfly from flower to flower, you take up the
cockchafer and put it on a bed of fresh leaves, with a straw you drive
the cricket from its hole. The insect that amuses you can also instruct
you. In our modest studies let us now have a little talk on this
subject.
“What is this tiny creature with the stout coat-of-mail of chestnut
color? Its large head, showing parallel folds that might have been
carved by a sculptor’s hand, is armed with two branching nippers which
open like a pair of tongs and then close, mangling between their teeth
the finger they have seized. Woe to the giddy-pate that lets himself be
caught by them! The trap closes tighter and tighter and never lets go.
“But, vigorous as are its mandibles, the insect is not one to be afraid
of, provided only you look out for those nippers. For all its
threatening aspect, it is at bottom a peaceful creature. Catch it by
one leg and it will fly round and round like the June-bug. It is called
the stag-beetle, a name that explains itself, for it has branching
mandibles resembling a stag’s horns, and it belongs to the family of
beetles. Put the two words together and you have ‘stag-beetle.’
“The singular creature has not always been as we see it to-day. In its
youth, not later than last year, it had neither its present mandibles
nor its six legs nor its chestnut-colored coat-of-mail. In fact, its
form had nothing in common with what we now behold. Then it was a big,
fat worm, with fine white skin, crawling on legs so small and feeble as
hardly to deserve mention.
“The whole animal consisted of little more than a crawling stomach
unprovided with any protection. The head alone was fortified with a
substantial skull of horn, and it also bore, one on the right side of
the mouth, the other on the left, two short but strong teeth adapted to
cutting in pieces the wood of the oak, its sole nourishment.
“Such a worm, entirely naked, evidently cannot live in the open air,
where the thousand little roughnesses of the ground would be
continually wounding its delicate skin. It must have a safe shelter
that it need not leave until it has become the well-armored insect we
now see. The grub of the stag-beetle does in fact live inside the oak,
which affords it at once food and lodging. There, in the depths of the
tree-trunk, is its inviolable retreat.
“With its two teeth, as hard and sharp as a carpenter’s tool, it cuts
away, patiently, bit by bit, the fresh wood imbued with sap. Each
fragment thus detached is a mouthful for the worm’s nourishment; but as
it is by no means a rich diet there must be a good deal of it to
furnish enough nutriment. Therefore the gnawing goes on without
cessation, in all directions, with a corresponding enlargement of the
domicile, which soon becomes a labyrinth of galleries that go up and
down and cross one another, penetrate farther into the trunk or
approach the surface, at the pleasure of the occupant, whose choice is
determined by its taste for morsels lying in this or that direction.
“For three or four years this is the worm’s mode of life. To make
itself big and fat is its sole business, and to this it devotes itself
with vigor. I leave you to imagine what must become of an oak tree
worked by a dozen of these gnawing creatures. Under the bark, which is
almost intact, the trunk is one vast wound, perforated with galleries
that are themselves littered with wormhole dust, and oozing with a
brown juice that smells like a tannery. Unless the forester applies a
remedy, and that speedily, the enormous oak will be ruined. Leaving
this care to his charge, let us go on with our story.
“When it has become big enough and fat enough, after at least three
years of continual feasting, the worm prepares to change its form. Near
the surface, that its future exit may be the easier, the little
creature hollows out a sufficiently large oval chamber and lines it
with a sort of wadding made of the finest fibers of the wood. Thus the
tender flesh of the rejuvenated insect will be protected from all rude
outer contact.
“These precautions taken, the worm undergoes its transfiguration: it
splits open all down the back, strips off its skin, throws it away like
a discarded garment, and is born a second time, as one might say, but
under a totally different form. It is no longer a worm—far from it—but
it is not yet a stag-beetle, although the outlines of the latter are
already discernible.
“The creature is quite motionless, as if dead. The legs, neatly folded
over the stomach, are as transparent as crystals; the nippers are
pressed close to the breast; the wings, not yet expanded, have the
appearance of a short scarf encircling the flanks; and the whole is
swathed in swaddling-clothes finer in texture than an onion skin. The
entire organism is wrapped in a repose so profound that one might think
all life extinct. It is white or crystalline in appearance, and so
tender that a mere nothing will wound it. The coarse worm of the
beginning has been succeeded by this most delicate of creatures.
“Out of the material amassed by the wood-gnawer’s voracious appetite
there is created an entirely new being. The flesh, at first nearly
fluid, slowly acquires consistency; the skin hardens, assumes a
chestnut hue, takes on the firmness of horn; in fact, when the warm
season returns again the insect wakes up from that deep sleep, not of
death, but nevertheless very much like it. The creature moves, tears
apart the swathing bands under which its rebirth has taken place,
strips off these wrappings, and here at last we have the insect in its
full perfection. Behold the stag-beetle!
“It comes out from its native oak, spreads its wings in flight under
cover of the foliage, and settles down, now on this tree, now on that,
in the rays of the sun. The freedom of the open air and the enjoyment
of the light of day constitute its supreme felicity for which it has
been preparing during the three or four years of constant toil in the
dark galleries of an old oak.
“Thenceforth it grows no larger. Just as it was on emerging from its
cell, so it will remain to the end, without the least increase either
in weight or in bulk. Thus it leads a very staid existence. In its grub
state the famished creature gnawed wood night and day; its life was a
perpetual digestion. Now, on the contrary, all that it needs in the way
of sustenance is an occasional sip of the sweetened sap oozing from the
bark of the tree.
“But its days of idle delight are numbered; it has scarcely a couple of
months to spend joyously among the oak trees. Then it lays its eggs,
one by one, in the crevices of tree-trunks, to propagate its kind; and,
that done, it very soon dies. It has played its part. From those eggs
will come forth worms which will patiently work their way into the
wood, hollow out galleries there in their turn, and begin all over
again the very sort of existence led by their fore-fathers.
“The greater number of insects have the same life-history as the
stag-beetle: they pass through different stages before taking on their
final form. All without exception, the smallest as well as the largest,
come from eggs deposited by the mother in chosen places where the
needed nourishment, so variable in different species, is easy to find.
“From the egg emerges, not the finished insect with all its distinctive
traits, but a provisional creature bearing, very often, no resemblance
to the parent or to the matured offspring of that parent. This initial
form we called a worm in speaking of the stag-beetle, and the name is
in that instance appropriate; but in a multitude of cases it would be
incorrect, having no agreement with the creature’s appearance. We then
call it a larva.
“The larva is therefore the insect under the form it presents on
emerging from the egg. Its continuance in this form is longer than in
that of the finally perfected creature. The larva of the stag-beetle
remains a larva for three or four years, whereas the beetle itself
lives but a couple of months. The sole occupation of this grub is
eating, continual eating, that it may grow fat and store up supplies
enough to carry it through its subsequent transformations.
“Having attained sufficient size, the larva constructs a retreat for
itself, hollows out a little cell, and spins a cocoon where in perfect
quiet the delicate task of transformation will be undertaken. It strips
off its skin and becomes an inert, formative body known as a nymph.
“Finally, the nymph, having arrived at the right degree of maturity,
casts off its wrappings and reveals itself as transformed into a
perfect insect. It lays its eggs, and the same succession of changes is
again repeated. The egg, the larva, the nymph, the perfect insect—there
you have the four stages of the insect’s life. These changes of form
are called metamorphoses.”
CHAPTER XLVI
SHEATH-WINGED INSECTS
“I show you here the scarab, clothed all in black. Passionate lover of
the sun, it rarely strays beyond the regions bordering on the
Mediterranean. It belongs to the band of scavengers, a group of
handsome insects which, feeding on ordure, are charged with the
sanitation of the greensward defiled by grazing herds.
“Its favorite dish is the dung of horses and mules. With the toothed
edges of its head it rummages in the dung; with its wide, serrate fore
legs it cuts up this material, kneads it, and molds it into a ball
about as large as an apricot. This done, the next thing is to seek out
some quiet retreat far from the hubbub of its fellows who have been
drawn to the spot for as much as a kilometer round about by the odor;
and of course the booty must be trundled away to this secure retreat,
there to be eaten at ease, without fear of predatory assaults from the
envious.
“This task is performed in couples. One hooks on to the globule in
front and pulls with head up; the other pushes from behind with head
down. Heave ho! It starts, it rolls, under the combined efforts of the
two partners. On the down grade the load again and again runs away with
the team, which falls headlong, gets up again, and catches hold of the
cargo once more with an ardor that nothing can discourage. Under the
rays of a scorching sun this store of provision is thus dragged a long
distance over the sand, across the greensward, and over ruts. Perhaps
the scarabs find their bread at first not sufficiently compact, and
seek to give it consistency by rolling it on the ground. Every one
according to his fancy.
“At last a favorable spot is selected in a sandy tract. One of the two
proprietors hollows out in all haste a dining-room, while the other
stands guard without over the globular treasure, ready to defend it
stoutly against any chance marauder. As soon as the dining-room is
ready the provisions are stored away there, after which the two
colleagues shut themselves up in their domicile, safe from unwelcome
visitors, closing their door with sand. So there they are at table,
with their heap of victuals in front of them; and now for a good feast!
When the board is bare again, the two banqueters leave their dugout to
gather together a new globule and resume their feasting.
“The scarab is not found everywhere, the more’s the pity, for its
manner of life is very curious to watch. Wanting this manufacturer of
globules, we nevertheless do have everywhere other scavengers which
work in somewhat similar fashion. Out of ordure they put together
little balls of the size of a cherry, and sometimes they roll away
their plunder, as does the scarab, bury it in the ground, and there
regale themselves on it. Their trade of making these little balls or
pills has given them the expressive name of pill-mixers.
“Let us pass on to other kinds. This one, for example, is called the
calosoma. By reason of the elegance of its form and the richness of its
coloring it is one of the most beautiful insects of our region. Its
back has the brilliance of a gem such as no jeweler ever possessed. One
would really take it to be made of gold, but gold of a peculiar sort
and much richer than ours, flashing as it does with red, green, and
purple glints. There is nothing to compare with this dazzling costume.
It should be added that if the insect is taken between the fingers it
emits, as a means of defense, a strong odor reminding one of a
chemist’s disagreeable drugs.
“The calosoma does not share the scarab’s peaceful habits: it is an
ardent hunter and leads a life of carnage. Its prey is the caterpillar,
the bigger the better, whether smooth-skinned or hairy. If you happen
to find a calosoma, put it into a good-sized bottle and give it for
dinner a lusty young caterpillar as large as your finger. You will see
with what ferocious satisfaction this drinker of blood will disembowel
the poor worm, despite all its writhing and squirming, and will feast
on its green entrails.
“The carabid, which is also a passionate lover of game, has the
calosoma’s activity and brilliance, but is of smaller size. Some are
bronze in color, others golden, still others of a copper tint, or black
edged with a superb violet. All explore with keen scrutiny the thick
tufts of grass, and give chase to small prey such as larvæ,
caterpillars, and worms. The most common example of this class wears a
golden green coat and is a frequenter of gardens, where it makes war on
all kinds of vermin. It is the little guardian of our beds of peas and
beans, and of our flower borders. In honor of its services to the
garden we call it the gardener.
“The calosoma and the carabid do not fly; they are made for running, as
is evident from their long legs, their agile movements, and their lithe
form. They chase the game in hot pursuit, or else lie in wait for it
behind a leaf, but never pursue it on the wing. On the other hand, the
scarab, the common June-bug, and a host of other insects fly very
well.”
“But why don’t they all fly?” asked Emile.
“I will tell you,” replied his uncle. “Look carefully at the June-bug a
moment. It has two kinds of wings: on the outside two large and
substantial scales of horn, and beneath these two fine membranous
wings, expanded during flight, but carefully folded together and
concealed when not in use. The outside scales are called elytra, or
sheaths. They serve as a case for enclosing and protecting the delicate
membranous wings, which alone are fitted for flying. The carabid and
the calosoma have sheaths of splendid brilliance, it is true, but
beneath these sheaths there are no membranous wings to spread
themselves in flight and fold up again in repose. Hence these two
insects are unable to fly.
“The dytiscus and the hydrophile, whose names signify ‘diver’ and
‘water-lover’ respectively, both frequent the waters of deep ponds, of
ditches, and of pools. With their legs flattened out like oars, their
very smooth bodies, arched above and keel-shaped below, they are
first-rate swimmers and divers. It is a feast for the eye to follow the
graceful agility of their oars when they row calmly on the surface or
plunge beneath it.
“At the least alarm they dart quickly to the bed of the pond and take
refuge amid the water plants. On the instant of diving their belly is
seen to flash like a plate of polished silver. The reason of this
borrowed sheen is found in a thin layer of air that they carry with
them adherent to the belly. With this supply they will have air to
breathe until, all danger past, they ascend again to the surface.
“In the matter of costume these two master-swimmers are of modest
appearance. Both are of a very somber olive green, but in addition the
dytiscus wears faded gold lace on its sheaths. If the pond dries up or
ceases to please them, they can quickly betake themselves to
another—not on foot, for their flattened legs, excellent as oars, are
worthless in walking, but by flight, with the help of their membranous
wings, ordinarily hidden under the sheaths, where the water cannot
reach them.
“In old oak trees the larva of the capricorn-beetle, another ravager of
forests, leads much the same kind of life as does the grub of the
stag-beetle. Large in size, all black with gleams of chestnut, this
insect is remarkable for its jointed horns, which are longer than its
body. What can it do with these cumbersome ornaments? Does it wear them
on its forehead to intimidate the foe? I would not venture to dispute
the matter, but what I do know very well is that with its extravagantly
long horns it frightens the inexperienced young pupil so that he dares
not touch it, and he calls it the devil. All the same, the
capricorn-beetle does not deserve the evil reputation it has got from
the timid. It is perfectly harmless.
“Insects’ horns are called antennæ. All have them, some longer and some
shorter, now of one shape, now of another. In some instances they are
flexible filaments, jointed chaplets; in others, short stems ending in
either a cluster of little buds or a bunch of leaves pressed one
against the other. See for example the burly and magnificent insect
that browses the foliage of our pine-trees on warm summer days. It is
called the pine-beetle. On a chestnut background it wears a sprinkling
of white spots. The antennæ carry at the end a set of little plates or
scales which open and shut like the leaves of a book.
“It is in place here to mention the common June-bug, furnished like the
pine-beetle with antennæ bearing leaf-clusters at the end. I propose to
tell you its story in detail; for, if this little creature is the joy
of young people of your age, it is also the terror of the farmer.
“But first one word more to conclude our short story of sheath-winged
insects. Their number is immense. Nearly all have membranous wings
under the protecting case formed by the sheaths; and these can fly.
Others, relatively few, are unprovided with membranous wings, and hence
are unfitted for flight. This entire group bears the general name of
coleoptera, meaning sheath-winged. A coleopter is any insect furnished
with sheaths, whether it flies or not.”
CHAPTER XLVII
THE JUNE-BUG
“It is a discovery of no small importance in your eyes, my young
friends, when you find the first June-bug of the season on the young
foliage. In the evening you get together in a corner and talk about it,
you make plans for the morrow, and all your conversation is about the
June-bug that has just arrived. You arrange to get up early the next
day and shake the trees in order to bring down the sleeping insects;
you get ready a box, pierced with holes, to receive the captives, and
put in a handful of fresh leaves for them to feed on.
“At the first streak of dawn you are up; you visit the willows, the
poplars, the hawthorn hedges wet with dew. It is a fruitful hunt: the
June-bugs, benumbed by the chill of night, fall like hail when you
shake the branches. Soon you have a half a score of them, then a dozen,
then twenty. It is enough. You go back to the house with your prisoners
fluttering and struggling in the foot of an old stocking, in your
handkerchief, or in your cap. You bring a supply of green leaves.
“And now for your experiments! You tie a long string to the leg of one
of the beetles and put the insect in the sun. It inflates and deflates
its belly, raises its wing-sheaths, and expands its wings. There it
goes, into the air. Your experiment has succeeded. These delights of
the June-bug season, my children—enjoy them as long as you can. Other
pleasures pale beside them. In view of the amusement it affords you I
gladly welcome the June-bug. But turn now to a less pleasing aspect of
the matter.
“Like every other insect, the June-bug is at first a grub. In that form
it lives three years in the ground, whereas in its final state, when it
is found on trees and bushes, it lives but two or three weeks. This
grub or larva is commonly called the white grub, also the fish-worm,
and sometimes the ground-hog. Look at it carefully for a moment and
tell me what you see.”
“I see,” answered Louis, “a fat, big-bellied worm, slow in its
movements, and fond of lying curled up on its side. It is of a whitish
color with a yellowish head.”
“Yes, and what else?”
“It has six legs, not made for running on the surface of the ground,
but for crawling underneath; and it has strong jaws for biting the
roots of plants. Its head is capped with horn to help it in boring
through the soil.”
“Very good,” was Uncle Paul’s approving comment; “and you see how the
stomach is distended with food, which shows in a darker tint through
the white skin of the paunch. So gorged is the worm, in fact, that it
cannot stand on its legs, but lies lazily on its side.
“For three years this fat grub lives under ground, always under ground,
tunneling like a mole in all directions, and living on roots. Then it
makes for itself a little chamber out of earth, very smooth inside, and
shuts itself up there; after which it proceeds to transform itself into
a nymph, and then into a June-bug. Everything serves it for food: the
roots of grass and of trees, of cereals and of fodder, of vegetables
and of flowers. In winter it buries itself deep in the ground and
becomes torpid; at the approach of spring it returns to the upper
layers of the soil, installs itself among the roots, and goes from
plant to plant, leaving devastation in its path. You have, let us
suppose, a fine bed of lettuce in your garden. From no apparent cause,
some morning, you find it all withered. You pull up one of the plants,
and it proves to have no root; the white grub has cut it away. Or you
have a nursery of young fruit trees for your orchard. The terrible worm
passes that way, and your nursery is good for nothing but fire-wood. Or
you have sown several acres with wheat or rape, you have made a
considerable outlay for fertilizer and labor; but there is promise of a
handsome harvest with large profit to you. The larva of the June-bug
works its way up from the depths, and then good-bye to your harvest;
the stalks dry up as they stand, having no roots left to sustain them.
When this formidable worm invades a country, famine would surely follow
were it not that traffic facilities make possible the speedy
importation of provisions from other lands. We live in a progressive
age and, thanks to the means of transport and to the briskness of
trade, people do not die of hunger in a province whose fields have been
devastated by the white grub. They do not die of hunger, but what woe
follows in the wake of the devouring larva! Year in and year out, it
destroys millions of francs’ worth of crops in France alone.
“The multitude of these little insects is truly terrifying. When they
invade a field, the earth, undermined in all directions, loses its
firmness and yields under the pressure of the foot. One year, in the
department of the Sarthe, the ravages became so serious that it was
necessary to undertake a systematic destruction of the pest. The
June-bug was hunted on a large scale, and sixty thousand decaliters
were gathered in, each decaliter containing about five thousand
insects. Thus the total number taken amounted to three hundred
millions. To give you some idea of the immensity of this number I will
add that if you should try to count those three hundred million
insects, one by one, it would take you more than twenty years, working
ten hours a day.
“In the department of the Lower Seine there was at one time found to be
an average of twenty-three larvæ of the June-bug to the square meter,
or two hundred and thirty thousand devourers to each hectare. A hectare
will raise a crop of one hundred thousand beets. Thus each beet was
gnawed by at least two worms. Allowing eighty thousand rape-stalks to
the hectare, we find each stalk feeding three worms, or very nearly. It
is clear that under these desperate conditions no rape-seed oil or
beet-root sugar can be produced. Every plant perishes. In the single
year 1866 the Lower Seine lost from this cause about twenty-five
million francs.
“In 1868, in different parts of France, notably in Normandy, the
multiplication of June-bugs was so great as to spread alarm throughout
the rural districts. Trees were completely stripped of their foliage,
and in the evening, when the insects fly abroad, such clouds of them
encumbered the atmosphere as to make it difficult to walk about. Almost
everywhere there were June-bug hunts organized, and those who gathered
the insects received from the public treasury from four to six francs
per hundred liters. In one place alone, Fontaine-Mallet, near Havre,
there were gathered four thousand and fifty-nine kilograms of the
insects in four days. The school-master sent his pupils out after
June-bugs, and four hundred and forty kilograms was the result of one
day’s collecting. All these insects were carted to Havre by the
wagon-load and drowned in the sea. In certain communes they were
brought to the town hall in such quantities that there was no way of
disposing of them. The air reeked with the stench they made.
“It is said that in 1668 the June-bugs destroyed all the vegetation in
one county of Ireland, so that the country presented the dead
appearance of winter. The sound made by the insects’ mandibles in
browsing the foliage of the trees was like that of a carpenter’s saw,
and the hum of wings resembled the distant beating of drums. Enveloped
in clouds of insects and blinded by the living hail, the inhabitants
could hardly see to go about. The famine was horrible: the poor Irish
people were even obliged to eat the June-bugs to keep from starving.”
“Oh, how awful that must have been!” exclaimed the group of listeners.
“Yes, awful, indeed,” assented Uncle Paul, “and I have a few more
instances to relate, less lamentable than the Irish famine, it is true,
but still of a nature to show us how prodigious were the legions of
June-bugs in certain years. In 1832, in the neighborhood of Gisors, a
stage-coach became enveloped at nightfall in a cloud of these insects.
Blinded and terrified, the horses obstinately refused to go on. Finally
there was nothing to do but turn about and go back, so completely did
the humming swarm bar the way. Forty years ago the June-bugs descended
upon Mâcon after ravaging the vineyards in its vicinity. They were
scooped up in the streets by the shovelful, and to make one’s way
through the cloud of beetles one had to clear a passage by the
energetic brandishing of a stick.
“Since the June-bug is so redoubtable a scourge to agriculture, since
it is a foe with which one must reckon most seriously, how, you will
ask, is it to be got rid of? There is one way, and only one: collecting
and destroying both grubs and beetles. We can count to a certain extent
on the help of moles, hedge-hogs, ravens, crows, and magpies, all of
which hunt the larvæ, especially in newly ploughed fields; and we can
also count on the aid of a host of birds such as shrikes, sparrows, and
others, which devour the beetles; but the number of the enemy is so
great that this destruction by natural means does not always suffice.
We must then lend an energetic hand ourselves. Which of the two is to
enjoy the fruits of the earth, man or June-bug? Man, if he will but
bestir himself and wage unceasing war on both the insect and its larva.
“The white grub, as I told you, bores into the earth more or less
deeply according to the season. In winter it goes down half a meter, a
depth at which it is protected from the frost. Upon the return of
milder weather it comes up again, to be within reach of the roots; and
from the first of April it can be found by digging down twenty
centimeters. A favorable time, therefore, is chosen for turning up the
earth and bringing the larvæ to the surface, whereupon women and
children, following after the plough, gather up the white grubs in the
furrows. A single hectare has been known to yield in this way from two
hundred to three hundred kilograms of worms. The vermin are pressed
down into the earth with lime, the whole making an excellent manure,
and the enemy of harvests thus serves to accelerate their growth.”
CHAPTER XLVIII
CATERPILLARS AND BUTTERFLIES
“Of all insects butterflies are the most graceful, the most worthy of
childhood’s eager desire. Oh, how beautiful they are! Poised on a
flower, they seem to form a part of it and to animate it with the
gentle beating of their wings. You cautiously draw near, you crouch
down and make a quick clutch with the hand, but the beautiful creature
is no longer there. It is waiting for you on another flower, quite
unconcerned at your designs on its freedom. Let us leave it, then, to
flit from one cluster of lilacs to another, and occupy ourselves a
while with an account of its structure and habits.
“All butterflies have four wings suitable for flying, two upper and
larger ones, and two lower ones half hidden under the others. Here we
find no horny sheaths such as are worn by the scarab and the June-bug,
no protecting case under which the membranous wings are folded to guard
against laceration. The scarab is a clod-hopper, well acquainted with
the harsh irregularities of the ground. He pursues his plodding course
on foot, and it is only rarely that he spreads his wings in flight. The
butterfly is a delicate creature of the air, very seldom using its legs
for walking, but finding them of service when it alights upon a flower.
It has, therefore, four broad wings, wide-spread and always ready for
flight.
“And what wings! Words are lacking to describe them fitly. Some are
white as if coated with flour, others sky-blue, and still others
sulphur-yellow. Again you find them of a flame-like red or dark
crimson. Some have round spots like eyes, which look at you with their
large pupils encircled by azure, mother-of-pearl, or gold; and you will
see others speckled with black, adorned with silver lace, or fringed
with carmine. If you touch them they leave on your fingers a brilliant
powder beside which the filings of the precious metals would look dull.
“This dust might be called the butterfly’s plumage. It consists of
scales of extreme delicacy, placed regularly side by side like the
tiles on a roof, and attached by one end to the membrane of the wing
just as a bird’s feathers have their quills implanted in its skin.
Grasped roughly between the fingers, the wing parts with its delicate
covering; it loses its ornamental scales and shows naked to the view.
It is then a fine, translucent membrane traversed by a network of tiny
ribs, or nervures, as they are called, which hold it expanded and give
it firmness.
“At rest, butterflies do not all carry their wings in the same manner.
Those that fly by day and go from flower to flower in full sunlight,
hold their wings erect on the back and folded against each other. These
butterflies are also recognized by their brilliant coloring, their
lightness on the wing, their grace of form. Those, [6] on the other
hand, that fly either by night or at evening twilight bear their wings,
in repose, either outspread or else lightly folded in a sort of
roof-shape. They are of bulkier form and heavier than the
first-mentioned, and sombre hues predominate in their costume.
“Whether friends of light or fond of darkness, whether courting the
sunshine or lovers of the night, butterflies are invariably very
abstemious, finding all the nourishment they require in the tiny drop
of honey exuding at the bottom of a flower. Many flowers have long and
narrow mouths; no insect muzzle is slender enough to reach into flasks
like these and lap up the syrup, and therefore butterflies must have a
special instrument adapted to the purpose.
“This instrument is the proboscis, as fine as a hair and long enough to
reach to the exquisite drop, however deeply it may be hidden. When not
in use, this proboscis is kept tightly coiled at the entrance to the
insect’s mouth. When it finds a flower to its taste, it uncoils this
spiral and extends the proboscis in a long thread which plunges into
the narrow-necked bottle and proceeds to suck up the coveted drop. If
we wished to drink from a flask of similar shape, we should use a straw
or reed. Its proboscis is the butterfly’s straw with which it takes its
refreshment from the flowers.
“As with other insects, the butterfly is at first a larva or worm, very
different, you understand, from what the creature will afterward
become. The larvæ of butterflies are nothing in the world but
caterpillars.”
“Oh, how disgusting!” cried Emile, making a wry face.
“But nevertheless so it is,” proceeded his uncle. “Caterpillars,
repugnant creatures to us, change into those magnificent butterflies
that we are never tired of admiring. What was ugly becomes beautiful,
what was frightful finds itself the proud possessor of grace and charm.
“There are some caterpillars that have the skin quite naked and mottled
with various colors in a manner not unpleasing to the eye. To touch
these worms, even to handle them, inspires little or no fear, so
harmless do they look. But there are others, of a larger size, which
carry on the back, toward the rear, a menacing horn, a sort of hook, of
which it seems prudent to beware. This apprehension, however, is
groundless: the horn is inoffensive, being not a weapon but a mere
ornament. Caterpillars thus equipped become large butterflies flying in
the late evening twilight.
“Still others have an even more repulsive look, bristling as they do
with clusters of prickles and with tufts of long hair. From these ugly
creatures, whose very touch would be so disagreeable to us and would
make us utter cries of fear, come some of the most beautiful
butterflies of our part of the world. Such is the caterpillar that
browses the leaves of the nettle and becomes the Vanessa Io or
peacock-butterfly. It is black with white spots, and wears a rough
armor of toothed prickles. The butterfly, the Vanessa, has wings of a
bright brick-red adorned with a large eye of mingled black, violet, and
blue. Who would ever imagine, unless he had seen the transformation or
heard about it, that so ravishing a creature has such an origin?
“But for all their hairs and prickles caterpillars need cause us no
alarm. Nothing about them justifies the fear they too often inspire. No
caterpillar is poisonous, no caterpillar seriously injures the hands
that touch it. Yet it is well not to repose full confidence in hairy
caterpillars: sometimes the hairs become detached and cling to the
fingers, causing rather lively itching sensations. But a little
scratching ordinarily ends the trouble. Accordingly any one who should
hereafter be afraid of caterpillars would not deserve the privilege of
chasing butterflies.
“Every larva is a gluttonous eater, because it must grow big and
accumulate the wherewithal for its subsequent changes of form. Nor are
caterpillars lacking in response to this serious duty. The future
butterfly’s welfare is at stake. Made solely for eating, the larvæ gnaw
and browse unceasingly. Each one has its own particular kind of
sustenance, its chosen plant, and nothing else meets the requirements.
The larva of the Vanessa selects the nettle and turns with aversion
from all substitutes; that of the Pieris, a white butterfly with black
spots, will have only the cabbage; that of the Machaon, a butterfly
with large wings that end in a sort of tail, feasts on fennel; and so
of others.
“After attaining the full size assigned to them by nature,
caterpillars, like other larvæ, prepare for their transformation. Some
shut themselves up in a cocoon made from a silken thread that they spin
from their mouth, while others content themselves with binding
together, by means of the small supply of thread at their disposal,
particles of earth, bits of wood, and hairs plucked from their own
body. Thus is obtained, at small expense, a sufficiently substantial
temporary abode. Finally, still others, especially among the
butterflies that fly in the daytime, merely seek a retreat on the side
of some wall or against a tree-trunk, and there suspend themselves in a
girdle of silk.
“These precautions taken, the caterpillar strips off its skin and
becomes a nymph, but very different from that which the stag-beetle
showed us. The coleopter, in its nymph stage, was already recognizable,
with its branching mandibles, its legs folded on its stomach, and its
wings enclosed in their sheaths. The butterfly, on the contrary, is not
at all discernible under the casing of the nymph. This nymph, with skin
as tough as parchment, is an object little indicative of its true
nature and much more suggestive of the kernel of some strange fruit
than of any animal form. Because of its shape, so different from that
shown to us by ordinary nymphs, it has received a special name, that of
chrysalis.
“This word means golden sheath. Sometimes, notably in the case of the
Vanessa, the chrysalis is adorned with gilding; but in the great
majority of instances the suggestive name is not deserved, a uniform
chestnut hue, darker or lighter, being the usual color of the
chrysalis. Ripened by long repose, this species of animal shell splits
down the back and releases the perfect insect, complete in all its
attributes. The butterfly passes a few festive days amid the flowers,
and before dying lays eggs whence will spring caterpillars to continue
the race.”
CHAPTER XLIX
ANTS
“Ants live in communities, each containing many members, in underground
abodes, where the young are reared. These communities are composed of
three kinds of insects: males and females, recognizable by their large
transparent wings, four to each ant; and the neuters, or workers, which
have no wings. These last, the workers, build the house, take care of
the community, rear the larvæ and bring them their food, distributing
it to each one. The others do not work. To add to the population by
furnishing an abundant supply of eggs is all that they are expected to
do.
“As soon as the rays of the morning sun strike the ant-hill, the
workers standing watch at the entrance hasten within, nudge their
comrades with their antennæ to wake them up, run from one to another,
urge them on, hustle them into activity, and put all the subterranean
galleries into lively commotion. First of all, attention must be given
to the larvæ, feeble transparent worms, without feet and unable to feed
themselves and to grow unless they receive assiduous care from their
nurses.
“Accordingly, aroused by the tumult caused by the workers rushing in
from outside, the ants proceed to busy themselves with the larvæ and
also with the nymphs, carrying them with all possible expedition into
the open air and placing them where they will best be exposed for some
time to the benign influence of the sun’s heat. After this sun-bath
they are returned to the darkness and stowed away in chambers expressly
prepared for them. And now is the time for feeding the nurslings.
“Just as little birds receive the beakful of food, so do the larvæ take
their nourishment. When they are hungry they raise themselves a little
and seek the mouth of some one of the workers engaged in ministering to
them. The nursing ant opens its mandibles and lets a tiny drop of
sweetened liquid be taken from its mouth. Thus, one suck at a time, the
nutritive juice is distributed until the entire brood is fed.
“But carrying the larvæ into the sun and feeding them will not suffice:
they must also be kept in a state of extreme cleanliness. The workers
bestow upon their charges the same tender care that the mother cat
exercises toward her kittens. Over and over again they lick the
nursling’s body to give it perfect whiteness, and they tug cautiously
at the wrinkled skin when the transformation draws near.
“Before casting this skin the larva spins itself a cocoon of silk,
elongated and cylindrical in shape, pale yellow in color, very smooth,
and compact in texture. Under cover of this protecting sac, the worm
becomes a nymph. In this form the ant assumes its final shape, lacking
only strength and a little firmness. All its members are distinct, but
enveloped in a fine membrane which it must strip off to become a
perfect insect.
“If you disturb an ant-hill you will see the workers hastening to carry
away and put in a safe place certain cylindrical bodies having somewhat
the appearance of grains of wheat and very inappropriately called
ant-eggs. They are not the eggs of the insect, which are in reality
much smaller; they are cocoons with their contents, larvæ at first,
nymphs later.
“When the time comes for leaving its cocoon, the enclosed ant is unable
of itself to gain its freedom by piercing with its mandibles the silken
envelope; it possesses nothing resembling the solvent liquid which the
silk-worm holds in reserve in its stomach; nor has it at the forward
end of its prison-cell a door for exit analogous to the curious paling
provided for the great peacock-butterfly. It would perish in its silk
sack if the working ants did not bestir themselves for its deliverance.
“Three or four of these mount the cocoon and strive to open it at the
end corresponding to the prisoner’s head. They begin by weakening the
texture of the sac by tearing away a few threads of silk at the point
where the opening is to be made; then, nipping and twisting the tissue
so difficult to break through, they at last succeed in puncturing it
with a number of holes near one another, whereupon the mandibles are
applied at one of these holes just as one would apply a pair of
scissors, and a narrow strip is cut away. At this hard labor the ants
work in relays, toiling and resting by turn. One holds the narrow strip
that has been cut, while a second enlarges the opening, and a third
gently extricates the young ant from its natal sac.
“At last the insect comes forth, but unable to walk or even to stand on
its legs, for it is still enswathed in a final membrane which it cannot
strip off unaided. The workers do not forsake it in this new
predicament; they free it from the satin envelope enwrapping all its
members; with delicate care they extricate the antennæ from their
sheaths; they disengage the feet and set the body at liberty. Then the
young ant is in a condition to walk about and, above all, to take
nourishment, which it greatly needs after all this fatiguing exertion.
Its liberators vie with one another in offering the mouth and
disgorging a little sweetened liquid. For some days longer the workers
keep a watchful eye on their new companions and follow them about,
acquainting them with the labyrinthine passages of their abode. Thus
instructed, the young ants mingle with the others and share their
labors.
“The nurses remaining at home to perform the household duties depend
for their rations on the workers that go out to collect supplies. These
latter bring them little insects, or pieces of those that they have
dismembered on the spot when the entire prey is too large for
conveyance. Whatever they may be, these provisions are passed around
and are speedily disposed of by the assembled company. If the working
ants chance to find ripe fruit or large pieces of game that cannot be
divided into small parts, they adopt another mode of procedure. Placed
in possession of so great riches, they content themselves with the
juice alone, of which they imbibe copiously, then return home with
stomachs full of liquid food which they disgorge, drop by drop, as fast
as their hungry comrades present themselves.
“The ant in need of nourishment strikes rapidly with its antennæ those
of the ant expected to render the desired assistance. Presently they
are seen to approach each other with open mouths and tongues out in
readiness for the transfer of the nutritive liquor from one to the
other. During this operation the ant receiving the mouthful of
sustenance keeps up an uninterrupted caressing, with fore legs and
antennæ, of the ant ministering to its needs.
“Who is not familiar with the lice that infest plants, assembled in
dense groups that contain each more members than one could easily
count? There are black lice on the beanstalks, green ones on the
rosebushes, their stomachs carrying, behind, two little tubes whence
oozes from time to time a tiny drop of liquid. This liquid is the ant’s
main dependence for food. Let us follow an ant on its rounds among the
plant-lice.
“It goes hither and thither among the motionless herd, which is nowise
disturbed by its presence. Having found what it is after, the ant
stations itself close to one of the lice, which it proceeds to caress
with gentle taps of its antennæ on the little creature’s stomach, first
on one side, then on the other. The milch-louse allows itself to be
seduced by these friendly overtures, and a drop of liquid oozes out at
the end of the tubes, the ant sucking it up at once. A second louse is
visited, and it too is solicited in the same caressing fashion. It
yields its drop of liquid and lets itself be milked, after which the
ant passes without delay to a third louse, which it coaxes in like
manner. A fourth, probably already drained, withstands the wheedling,
whereupon the ant, perceiving that nothing is to be hoped for there,
proceeds to a fifth member of the herd and obtains what it desires. A
few of these mouthfuls are enough to satisfy an ant, and then it
returns to its home.
“Certain ants are great stay-at-homes: for them it would be a painful
infliction to have to go out into the world. In order to spare
themselves this necessity they raise plant-lice and pasture them in
enclosures very near the ant-hill so that the milking may be done at
leisure. These herded plant-lice are their precious possession, and the
community is more or less rich as it owns more or less of this
property. It constitutes the ants’ flocks and herds, their cows and
goats. They build underground stables among the grass-roots, and there
keep the plant-lice which they obtain from a distance, just as we
gather our domestic animals under the roof of barn or fold.
“Others display an even more curious ingenuity: they take possession of
the lice living on some branch or twig of a growing bush, and,
jealously watchful of their cattle, suffer no stranger to come and lay
claim to the food-supply they themselves are preparing to appropriate.
With their mandibles they drive off all intruders; they patrol the twig
in vigilant defense and stand careful guard over their herds. If the
danger becomes too menacing, they hasten to carry away their livestock
and pasture it elsewhere, in a safe place.
“Or, as still another device, they take little pellets of earth and
build around the twig a sort of pavilion, a structure with a very
narrow opening, a sheep-fold, in a word, with a few leaves growing
inside it and furnishing sustenance to the enclosed flock. In this
quiet retreat the proprietors milk their ewes, safely sheltered from
rain and sun and, most important of all, from alien ants.
“We have in this region a rather large reddish ant known as the red ant
or Amazon ant, which cannot without help build its house, raise its
larvæ, procure food, or even eat food; but with its hooked mandibles it
is admirably equipped for fighting and pillage. Slaves are the object
of its predatory raids, slaves to feed it, to go out after provisions,
to build the ant-hill, and to rear the young. A small black or drab ant
is the object of its slave-hunting excursions.
“In battalions of some thousands each the reds go forth in quest of a
nest of drabs. They break into the ant-hill notwithstanding its
occupants’ resistance, and sack the underground city. Presently they
take their departure, each with his plunder between his mandibles. They
carry away, not the full-grown ants, since these could not be trained
to serve in the strange ant-hill and would speedily make their way back
to their former home, but the young ones, and the nymphs shut up in
their cocoons.
“Hatched in the domicile of the reds, the ants issuing from the stolen
cocoons look upon the natal ant-hill as their own and there fulfill
their customary duties with diligence. They go out after provender,
undertake all building operations, care for the larvæ of the Amazon
ants, and feed their big and stupid conquerors who, once in possession
of enough slaves, never leave home again.”
CHAPTER L
THE ANT-LION
“On the margin of ponds and streams we may see, flying from one bulrush
to another, certain insects with large transparent wings and abdomen
long and slender like a piece of string. Some are of a bronze green
color, others of a splendid indigo blue, while still others, somewhat
larger, are clothed in mingled black and yellow. They are called
libellulids or, more commonly, dragon-flies, and also devil’s
darning-needles.
“Do you recognize the insect? Haven’t you ever run after it? Perched on
a reed that trembles in the current, it seems to be dozing and waiting
for you, its wings extended to the utmost. Your hand darts out to seize
it. Good-bye, darning-needle! It is ten paces away from you.”
“Yes, indeed,” replied Louis, “every one has chased darning-needles,
but I never knew of any one’s catching them. And we don’t have to go so
far as the brook or the mill-pond to find them, either.”
“No; not all of them are lovers of water. Some, in fact, avoid it and
prefer sandy places parched by the burning sun. A modest gray is their
uniform, but they make up for their lack of brilliancy by their curious
mode of life while they are still in the larva form. The picture that I
show you here illustrates what these gray dragon-flies look like at an
earlier stage.
“A singular creature and not exactly ingratiating in appearance. It
would not be very pleasant to encounter one in a lonely nook in the
woods, little adapted though its size is for attacking us. Look at its
ferocious pointed nippers, opening and closing like a pair of tweezers.
Do they not betoken a thirst for blood? As a matter of fact, the little
creature lives by carnage exclusively; it is a hunter whose game is the
ant. Hence its name of ant-lion, or, as it might be put, the lion of
the ants.
“Prey of that sort is incapable of serious resistance when once it has
been seized by those terrible hooks; but it must first be seized, and
there is the difficulty. The nimble ant scampers off at the first
approach of danger, and if it should chance to be hard pressed it has
only to run up a blade of grass and there be out of reach. The
ant-lion, on its part, heavy of paunch and short of leg, drags itself
along very awkwardly; and, moreover, if it ever undertakes to get over
the ground—a rare occurrence—it always moves backward, which is not
what might be called a speedy gait and does not adapt itself to keeping
the object of one’s pursuit always in sight.
“The chase being thus rendered impracticable, there remain the snare
and the ambuscade. The creature must capture by cunning what its
sluggishness of movement makes it impossible to get possession of
otherwise. Let us see what form this cunning takes.
“Hunt at the base of sun-exposed walls and rocks, and if you find there
some little nook with very fine and dry sandy soil, the ant-lion will
seldom fail to be there too. Its abode is easily recognized by the
regular funnel-shaped hollow scooped in the ground. The insect itself
is invisible, being hidden under the sand at the bottom of the
excavation.
“With the blade of a knife thrust obliquely into the ground lift up the
bottom of the funnel, and you will have the little creature, rather
abashed at first by the sudden destruction of its retreat, but soon
recovered and striving to hide itself in the soil by a backward
movement. Make haste to take it and put it into a glass under a layer
of fine sand like that beneath which you found it. There at your
leisure you can watch it as it hollows out its funnel, a pitfall for
catching ants. You will see it put into practice the cunning wiles of
an ambushed hunter.
“Let us for a moment stand as onlookers, mentally at least, while this
work goes forward. Placed on a bed of sand and restored from its former
dismay, the ant-lion proceeds to plunge its belly halfway into the
soil; then, with this substitute for a plowshare, and always moving
backward, it draws a circular furrow. Returning to its starting-point
it draws a second furrow close to the first, then a third next to the
second, and so on with a great many more, each one of smaller
circumference than the preceding, so that they all together form a
spiral which constantly approaches the center; and as this living plow
is driven deeper and deeper at each circuit, and throws outward the
soil that it turns up, the final result is a funnel of about two inches
in diameter and somewhat less in depth. There you have the ant-lion’s
trap, the treacherous pitfall in which the ants are caught.
“Of course the huntsman employing such a device as this must himself
keep well out of sight. The ant-lion is too well versed in its art to
violate this elementary principle. It crouches down under the sand at
the lowest point of the upturned funnel, with only its nippers showing,
and these are pressed close to the ground, but wide open and ready to
seize any luckless ant that may chance to tumble down the incline.
Although the horrible pincers are exposed, they are not likely to
excite suspicion, being easily mistakable from the edge of the
excavation for some stray bits of dead leaves.
“These preparations completed, the insect lies in wait, perfectly
motionless. Its patience and its hunger are subjected to prolonged
trial. Hours and even days pass with no sign of game. Alas, how
difficult it is in this world even for an ant-lion to win its mouthful
of bread!
“But at last there comes an ant, on business bent that takes it into
these parts. Preoccupied with its own concerns, it takes no heed of the
pitfall. Hardly has it approached the edge of the chasm when the sand,
which is extremely unstable, gives way under the little creature’s
feet. There is a land-slide, and with it down tumbles the incautious
ant. In mid-course it succeeds by desperate efforts in arresting its
descent. It struggles to regain the upper level; its tiny claws,
trembling with fear, catch as best they may at the roughness of the
slope; but as soon as touched these supports yield, and the down-rush
begins anew with irresistible impetus.
“One grain of sand, more firmly planted than the rest, offers some
resistance. Perhaps safety will be found in this point of support if it
continues to withstand the strain. It holds firm, surely enough. The
ant climbs up a little, heedful of its steps for fear of precipitating
another slide. It has almost gained the edge of the excavation and
seems about to find its feet once more on firm ground. Will it indeed
escape scot-free?
“Oh, no. The hungry watcher at the bottom of the funnel will have
something to say on that subject. He intends to make a good dinner on
the ant. If things had followed their customary course and the
imprudent victim, caught in the trap, had continued to slide down until
within reach of the nippers, these would have seized their prey without
further formality; but since the game seems about to escape, it is the
huntsman’s part to employ the manœuvres reserved for difficult cases.
“The ant-lion’s head is flat and somewhat shovel-shaped. The insect
plunges it into the sand and then, with a sudden movement of the neck,
throws the shovelful up into the air so that it will come down again on
the ant. Other shovelfuls follow in quick succession, better and better
directed, and fall back in a hail-storm on the now nearly exhausted
ant.
“Against this shower of sand resistance is impossible when one stands
on a treacherous footing that gives way at each attempt to escape. The
poor victim is swept away and rolls to the bottom of the funnel.
Instantly the nippers seize their prey, and all is over. The huntsman
goes to his dinner, not gnawing the fruit of his patient skill, since
it is too tough for that, but sucking the juice like the refined
epicure he is.
“When there is nothing left of the ant but a dry husk, the ant-lion
loads it on to his head and with an upward toss throws it out of the
funnel, in order not to defile his place of ambush with a useless
corpse which might arouse the distrust of passers-by. Then a little
careful mending restores the pitfall to its former mobility, and the
huntsman waits patiently for another ant to take a false step and slide
down into his lair.”
CHAPTER LI
VENOMOUS ANIMALS
“Among venomous animals there are some whose poisoned weapon has no
other purpose than to serve as a means of defense. Such is the bee, the
worker in honey of our hives; such also is the burly, hairy bumblebee,
which also gathers a store of honey, but keeps it underground in rude
little pots of wax. Let us not molest them at their task, either
intentionally or otherwise, and they will not molest us. If we irritate
them, they straightway draw on the aggressor and stab him with their
venomous dagger. This weapon they carry for defense, not for attack.
“But there are other and more redoubtable creatures that use their
venom for killing quickly, and without any dangerous struggle on the
victim’s part, the prey on which they feed. Of course the offensive
weapon is capable of becoming also a defensive one in moments of peril:
that which serves to kill the prey serves likewise to repel the enemy.
Among animals making this double use of their venomous weapon, first
for attack and then for defense, let us note the scorpion and the
viper.
“The scorpion is a hideous creature and of interest to us solely on
account of its sting. It has a flattened stomach, dragging on the
ground, and no distinct head. In reality it has a head, but so little
differentiated from the rest of its body as to give a truncated
appearance to the whole. On each side are four feeble legs, and in
front a big pair of nippers like those of the crab. Behind is a sort of
jointed tail, the terminal joint of which, more swollen than the
others, serves as reservoir for the venom. It ends in a hook, very
sharp and with a microscopic perforation at the point, from which the
venomous fluid escapes at the instant of attack.
“In this jointed tail with its terminal sting you behold the scorpion’s
implement of the chase, a terrible weapon which kills immediately, at
one stroke, any small game the animal may have seized. It is carried
bent over on the back, ready to inflict its deadly wound in front or
behind with the suddenness of a released spring. The two-jawed nippers,
of which only one jaw moves, are harmless despite their menacing
appearance. They are a sort of tongs used by the animal to hold within
reach and prevent from escaping the prey it is about to sting.
“The scorpion is carnivorous, feeding on all game adapted to its size,
such as wood-lice, insects, spiders. Endowed with but little agility,
it leaves its lair by night and under cover of the darkness hunts its
sleeping prey. Let us suppose it to chance upon a big spider. That is
indeed a succulent morsel, but its capture involves danger, for the
spider on its side is armed with two venomous fangs in its mouth. Being
both thus equipped with deadly weapons, which of the two will succumb?
It will be the spider.
“The scorpion seizes it with its two nippers and holds the victim far
enough away to avoid the risk of a bite. Then the coiled tail quickly
straightens out over the scorpion and proceeds to inflict a sting on
the helpless captive. It is all over. The stricken prey gives a
momentary shudder in its death agony and then collapses, lifeless. The
huntsman can now feast on his victim at leisure and in perfect
security.
“We have in France, in the southern departments, two species of
scorpions, of which the smaller and more common is of a greenish black.
Its customary haunt is under the stones at the base of old walls, the
favorite lurking-place of the wood-louse and the spider; but it also
very often finds its way into human habitations, where it hides in dark
corners. In rainy weather it snuggles under the linen laid away in
cupboards, and even creeps under the bedclothes. Not a pleasant
experience is it to find this baneful intruder, some fine morning, in
the foot of one’s stocking. One shakes out the frightful creature and
treads it under foot. If it has stung you, the pain is no joke, though
not seriously dangerous.
“The other species, much larger and far more to be dreaded, is found
almost exclusively in Languedoc and Provence. It is straw-color in hue
and inhabits sandy hillocks where the sun beats down with the fiercest
heat. There, under some large stone, it digs itself a den, a spacious
retreat, whence it issues only by night in quest of something to eat.
It is never known to intrude into houses, nor does it ever leave the
warmth of its desert solitudes. Unless you disturb it by lifting up the
flat stone that roofs its abode, you run no risk of encountering the
sting; but woe to the reckless one who should rashly venture to rummage
in that retreat. The creature’s sting is sometimes deadly, they say.
“The viper makes its home, by preference, on some warm and stony
hillside, where it lurks under the stones and in the tangled
underbrush. Its color is brown or reddish, with a darker zigzag stripe
on the back and a row of spots on each side. Its belly is of a gray
slate-color, and its head, larger than the neck, is blunted as if cut
off in front.
“It is an extremely timid creature and never attacks man except in
self-defense. Its movements are brusque, irregular, and heavy. Like all
serpents it feeds on live prey, especially insects and small
field-rats. To capture these quickly and to deprive them of the power
to defend themselves, the viper first inflicts a venomous wound, as
does the scorpion.
“All serpents dart out and in between their lips, with extreme
velocity, a black, thread-like member, forked at the end and of great
flexibility. Many persons take this to be the reptile’s sting, though
in reality it is nothing but its tongue, a tongue void of offense and
used by its possessor to snap up insects and also to express, in the
snake’s peculiar manner, by quickly passing out and in between the
lips, the passions that agitate the creature. All serpents have this
sort of tongue, but in these regions it is only the viper that
possesses the terrible weapon for inflicting venomous wounds.
“This consists, first, of two fangs, or long, sharp teeth, situated in
the upper jaw. These curved teeth are movable, starting up for attack,
at the reptile’s will, or lying down in a groove of the gum and
remaining there as inoffensive as a stiletto in its sheath. Thus the
risk of a self-inflicted wound is avoided. These fangs are each pierced
from end to end with a narrow channel having at the tooth’s point a
minute opening through which the venom is discharged into the wound.
Finally, at the base of each fang is a tiny sac filled with venomous
liquid. As with the bee and the scorpion, this liquid is harmless in
appearance, free from odor, and without taste—little else than water,
one would say. When the viper attacks with its fangs, the venom-sac
presses a drop of its contents into the dental canal and the terrible
liquid passes into the wound. In short, the whole operation exactly
corresponds to the similar procedure I have described in speaking of
the bee’s sting.
“Let us suppose you are so imprudent as to disturb the reptile as it
lies asleep in the sun. Immediately the creature uncoils itself and,
with jaws wide open, smites your hand. It is all over in a twinkling.
Then, with the same rapidity, the viper recoils itself and settles back
again, continuing to threaten you, with its head once more the center
of the spiral coil.
“You do not wait for a second attack; you beat a hasty retreat; but,
alas, the harm is done. On your wounded hand you discover two tiny red
spots, apparently of little more significance than the sting of a bee.
No cause for alarm, you say to yourself if you are unacquainted with
the effects of such a wound. But it is a false reassurance.
“Presently the red spots are encircled with a zone of livid hue. With a
dull sensation of pain the hand becomes swollen, and gradually the
swelling extends to the entire arm. Before long there follow cold
sweats and a feeling of nausea, breathing is rendered difficult, vision
is clouded, the intellect is torpid, and unless timely aid is rendered
death may be the sequel.
“What is to be done in the face of such danger? One must press tightly
or even bind fast the finger, the hand, the arm, above the wound, in
order to prevent the passage of the venom into the blood. The wound
must be made to bleed by the exercise of pressure all around it; it
must be energetically sucked to draw out the venomous liquid. I have
explained to you in speaking of the bee, and I now repeat it, that
venom is not a poison. It will not act, however powerful it be, unless
it mixes with the blood. Sucking it, therefore, is without danger if
the lining of the mouth is intact.
“It is plain that if, by energetic suction and by pressing until the
blood flows, we succeed in extracting all the venom from the wound, the
latter will henceforth be of no serious importance. For greater
security, as soon as possible the wound should be cauterized with a
corrosive fluid, such as ammonia or nitric acid, or even with a red-hot
iron. Cauterization acts in such a manner as to destroy the venomous
matter. It is painful, I admit, but one must submit to that in order to
escape something worse.
“Cauterization falls within the physician’s province; but the
preliminary precautions—ligature to stop the spread of the venom,
pressure to make the envenomed blood flow, and suction to extract the
venomous liquid—are matters for our personal attention; and all this
should be taken in hand immediately, since the longer the delay the
more serious the case becomes. When these precautions are taken it is
very seldom that the viper’s bite has fatal consequences.”
CHAPTER LII
THE PHYLLOXERA
“In our talks on ants a few words were said concerning their
milch-cows, plant-lice. You haven’t forgotten those curious herds with
udders in the form of two little tubes that emit, from time to time, a
sweetened liquid. The ant comes and milks these cows, caressing them as
it does so with its two antennæ. It fills itself with their milk,
making its stomach serve the purpose of a milk-pail, and then runs
back, all bursting with the delicious fluid, to disgorge it into the
nurslings’ mouths.
“These ant-cows are watched over with jealous vigilance; in case of
need they are pastured within enclosures, for fear of marauders. So far
all is for the best: the ants’ cattle afford us some passing amusement,
and apparently they are open to no serious reproach. But if we pursue
our inquiries further the plant-lice will reveal themselves to us under
a far more serious aspect.
“Let us speak first of rosebush lice. You wish to pluck a rose. Its
perfume fills the air, its form and color rejoice the eye. But just as
you are about to break the stem what do you find under your fingers? At
the base of the flower and all over the branch that bears it, the
superb plant is contaminated with a legion of green lice; a host of
odious vermin has taken possession of it; the magnificent has
associated with it the disgusting. The eye is offended; the fingers
recoil before this species of animated bark which the slightest
pressure turns into a sticky mush. Let us pluck the rose nevertheless,
and before shaking the lice from it let us examine them a moment.
“They are light green in color, big-bellied, and wingless. With a
little attention we distinguish the two minute posterior horns whence
oozes the liquid on which the ants regale themselves. They have,
underneath, a sucker, straight and very slender, a sort of bore which
they push into the tender bark to extract from it the juices on which
they live. The sucker once implanted at any convenient point, the
animalcule seldom stirs from that spot. If it does decide to move a
little, it is because its well has run dry and it must bore another
close beside it. A promenade of merely the length of the branch is a
liberty that only the most adventurous dare allow themselves. As a
rule, the plant-louse sticks to the spot where it was born, to the very
end.”
“But how can the stem of a rose get so completely covered with those
little green lice?” asked Emile.
“That is easily explained,” answered his uncle. “Plant-lice multiply
very rapidly, since each one, without exception, from the first to the
last, whatever their number, becomes capable in a few days of
procreating a family. The newly born settle down beside their mothers,
and are themselves soon surrounded by their own progeny. These in turn,
in a little while, have offspring of their own; and so on,
indefinitely, as long as the season lasts. Thus the stem, the branch,
the entire plant, become covered with lice so closely packed one
against another that in places the real bark is hidden by this bark of
vermin.
“Have you ever seen a garden-patch of broad beans overrun by black
lice? There, better than anywhere else, may be seen the rapidity of
propagation. On that green expanse appears at first a small black
stain, announcing the beginning of the invasion. It is a family of lice
installed at the top of a beanstalk, the tenderest part of the plant,
where the insects’ suckers can work to best advantage. The gardener, as
soon as he is aware of what is going on, hastens to cut off this part
of the stalk and crush it under his heel. He hopes to exorcise the evil
by destroying this nest of vermin.
“His hope is short-lived. A few days later, instead of one plant
invaded there are dozens. He lops off again; he turns up the remaining
leaves and examines them one by one; he crushes what vermin he finds,
taking all pains to make the extermination complete. Will he make an
end of it this time? Not at all: the black hordes reappear in greater
numbers than ever; the invaded stalks can no longer be counted. A few
lice that escaped the slaughter were enough to infest the whole patch
of beans. The foliage hangs down, foul and withered; the young pods,
riddled with punctures and corrugated with scars, shrivel up and can
grow no larger. For this ill there is no remedy; the harvest is ruined.
“The gardener pulls it all up and throws it on the dung-hill. His care
and vigilance have been unable to arrest the invasion. In vain he
crushed legions at a time under his angry heel: in a few days the
half-dozen survivors had propagated a larger colony than ever. Man is
hardly in a position to contend successfully against this lowly vermin
which braves extinction by virtue of its countless numbers.
“As I told you, the plant-louse does not like to change its place. It
plants its sucker on the very spot where it has just been born, and
thenceforth sticks to that spot, filling its stomach with sap and
surrounding itself with a family. This love of repose explains to us
very well how the twig of a rosebush or the top of a beanstalk
undergoes a progressive colonization; but it does not account for the
distant propagation of the species.
“With its home-keeping habits the insect ought to be confined within
narrow limits, on a single leaf and not on all leaves, on one rosebush
and not on the neighboring rosebushes. But as a matter of fact it is
disseminated everywhere. When one patch of beans becomes infested,
those in the neighborhood are equally unfortunate; when one rosebush
shows a colony of plant-lice, all those around it are similarly
visited. No vegetable growth can defend itself from the pest. How,
then, is it that this obese animalcule, which totters with fatigue
after one step forward, succeeds in passing from rosebush to rosebush,
from garden to garden? By what means is it able to spread in all
directions without limit?
“Let us examine a number of rosebushes, and we shall have a prompt
answer to our question. In addition to the wingless plant-lice, big of
belly and all grouped on the tender twigs, we shall see others, green
like the first ones, but more elegant in form, of greater freedom of
movement, and provided with four wings, very beautiful wings too,
diaphanous and gleaming with rainbow tints. These creatures are no lazy
sap-bibbers forever squatting over the well their sucker has bored.
They are seen to come and go, circulating briskly among the stationary
herd, inspecting the foliage, passing from branch to branch, and even
taking flight for some distant goal. They are the travelers of the
family. Their function is to propagate the race in the surrounding
district, with the aid of their wings, and even at considerable
distances when a puff of wind carries them thus far.
“Two classes, then, dissimilar though related, are to be noted among
the green lice of the rosebush and the black ones of the beanstalk, as
also among countless others. The members of one class have no wings;
they pass their lives where they were born, and multiply in serried
legions. Those of the other class, which is relatively small, are
equipped with wings. Confined to no one spot, they fare forth as some
passing breeze or their own strength of wing may determine, and deposit
in favorable localities the germs that are to serve each as the
beginning of a community of wingless plant-lice. The first kind
procreate on the spot with a fecundity almost beyond belief; the second
take leave of the stationary family and go out to start new centers of
population in various quarters. The first propagate without limit; the
second colonize.
“To soil the stem of a rose with a coating of lice is not exactly a
capital offense; but to lay waste a field of beans, the hope of the
farmer, is a far more serious matter. Yet even that is as nothing when
compared with other depredations committed by plant-lice. There is a
species of these insects that lives underground, subsisting on the
roots of the grape-vine. Oh, the hateful creature! Never has
agriculture known anything to equal the ravages it commits; no floods
or droughts or inclement seasons have ever wrought such woes. Its
terrible sucker has, up to the present time, caused us losses estimated
at the fabulous sum of ten milliard francs. What a mouthful for a
miserable little louse hardly visible to the naked eye! And to think
that the combined efforts of nations cannot succeed in exterminating
this pest! Alas, how feeble is mere force when confronted with the
exceedingly minute infinitely multiplied!
“This destroyer of the vine is known as the phylloxera, a name strange
to our tongue, but losing nothing of its impressiveness in translation.
‘Phylloxera’ means ‘witherer of leaves.’ The plant-louse thus
denominated does indeed cause the foliage of the vine to wither up—not
acting on the leaves directly, it is true, but attacking the roots.
These, done to death by the insect’s sucker, cease to draw from the
soil the nourishment needed by the vine. The vine-stock wastes away,
and with it the leaves, which become yellow and withered.
“It is not merely the foliage, then, that the phylloxera dries up; it
withers and kills the whole vine. Moreover, the name it bears was not
invented expressly for it, but was borne by another before the ravager
of vineyards became known. The louse that was first called phylloxera
lived at the expense of the oak-tree and took up its station on the
leaves, sucking the sap from them. There you have the true witherer of
leaves. The vineyard louse has therefore inherited an old appellation
which fails to indicate fully the seriousness of the creature’s
depredations.
“This last-named insect is a tiny yellowish louse, plump of body, but
hardly discernible to untrained eyes, its length being barely three
quarters of a millimeter. It lives in clusters on the minute
ramifications of the roots wherever the bark is tender enough to enable
it to push in its sucker. Its ranks are so dense that the infested
rootlets wear a continuous coating of vermin which stains the fingers
with yellow. It lays its eggs in little heaps in the interstices that
occur in the swarming colony; and these eggs are oval in shape and
sulphur-yellow at first, but turn brownish as the moment for hatching
approaches.
“From these eggs there come, in a few days, new layers of eggs, which
settle down beside the earlier comers and add their own progeny to the
already overgrown family. Thus, as long as the season continues
favorable, these myriad numbers of successive generations are added to
the existing myriads, until the thread-like rootlets become completely
hidden by the accumulated layers of eggs and the eggs themselves.
“Riddled with punctures, the rootlets swell up at intervals and present
the appearance of a string of elongated seeds. Thus deformed, fatally
injured in their delicate suckers, the roots cease to imbibe the
nutritive juices of the soil, the famished vine languishes for a time,
putting forth only feeble shoots that are incapable of bearing fruit,
and at last the whole plant dries up and dies. To secure its own
prosperity the louse has killed its nurse.”
CHAPTER LIII
THE PHYLLOXERA
(Continued)
“The yellow plant-louse found on the roots of the grape-vine,” resumed
Uncle Paul, “has no bent for traveling: wingless, sluggish, and
big-bellied, it is ill adapted to locomotion. Where once its sucker has
implanted itself, there the creature is glad to abide as long as the
place is tenable. But when the rootlet dies and begins to decay, then a
new refectory must be sought out, with a better-furnished table.
Accordingly the louse has to move. A persistent explorer, it knows how,
with patience and in course of time, to make its way through cracks in
the soil from one root to another, and dares even to climb to the
surface, where, proceeding in the open air, it emigrates from the
exhausted vine-stock to the neighboring one rich in sap; and there it
pushes down to the roots through some fissure in the ground.
“To this slow-goer a single one of our steps would be a journey of
excessive length. Therefore, to propagate its kind far and wide, it
must have other and quicker means than the extremely deliberate method
of locomotion just described. This other method for planting colonies
at a considerable distance has already been illustrated for us by the
green louse of the rosebush. Like that species, the phylloxera has a
special division of winged travelers, and it is these that propagate
the race throughout the grape-growing district.
“At the time of the greatest midsummer heat there make their
appearance, amid the throng of yellow lice covering the roots, certain
individuals with longer bodies, which soon change their skin and then
bear on their sides two pairs of black stumps, the sheaths of four
future wings. These are the nymphs destined for emigration. These
nymphs leave their subterranean abode and climb up to the foot of the
vine-stock, or sometimes even out upon the surface of the ground. There
another change of skin takes place, whereupon we behold the winged
insect, superior in form to its underground relatives.
“It measures a little more than a millimeter in length, not including
the wings. These latter, transparent and iridescent, extend far beyond
the length of the body, and the upper ones are wide, rounded, and
slightly smoke-colored at the end, the lower ones narrow and shorter.
They are supported by strong sinews that denote great power of flight.
With its large, diaphanous wings, its broad head and big eyes, its
belly ending in a blunt point, and its yellowish color, the traveling
insect bears some resemblance to a very small cicada. Such, in brief,
is the phylloxera commissioned to propagate the race at a distance.
“We have here no longer to do with the sluggish pot-bellied creature
that needs all its strength to move from one root to the next
adjoining; we behold an agile denizen of the air, capable of covering
with the swiftness of an arrow a distance of several leagues,
especially when aided by a favorable wind. During the warm season of
July and August these winged insects take flight and settle in swarms
on the vineyards not yet ravaged. They alight on the leaves, where
their suckers perform their function in sober moderation.
“To stuff themselves like gluttons, after the manner of their kindred
that live on the roots, is not their way. Hence their own depredations
are of no importance. Unfortunately, however, it is their mission to do
us a most disastrous disservice by infesting, one after another, the
adjacent vineyards, peopling the still unaffected districts with
underground ravagers. All take part in this; all, without exception,
set to work laying eggs.
“These eggs are few in number, it is true, each insect laying at most
but half a score amid the cotton-like down of the buds and young
leaves. But the aggregate is none the less enormous, since in this
strange family we have thus far encountered none but mothers. We have
just seen that all the wingless phylloxeras on the roots lay eggs, and
now we find that all their winged kindred on the leaves do likewise.
“This excessive fecundity would in the end exhaust the insect and
result in its extinction if there were no seasons of quietude for
renewing the vitality of the race. Yellowish in color like the eggs of
the underground phylloxera, those of the winged insect are of two
kinds: one of a larger size, the other only about half as large. The
first produce females, the second males. Here, at last, we have the two
sexes, whose coöperation will assure indefinite prosperity to the race.
That is the normal order governing all animal life.
“But what queer little creatures! Yellow, wingless, stubby, they look
like the lice on the roots, but even smaller. These phylloxeras of the
third kind are dwarfs in a family of dwarfs. They have no stomachs for
digesting, no suckers for puncturing the leaves and extracting their
sap. Self-nourishment, however slight, is not at all their affair. The
laying of eggs that shall renew the vigor of the race, the placing of
them where they will be safe, and then a speedy death—that is the sole
purpose of their brief span of life.
“For some days these dwarfs, male and female, wander over the vines and
mate, one with another; then, in the fissures of the wrinkled bark, the
mothers lay each an egg, a single egg, of enormous size in comparison
with the smallness of the layer, greenish in color and sprinkled with
fine black spots. This egg takes the name of ‘winter egg,’ being
destined to pass the cold season fastened by a little hook to the
vine’s bark. After this the layer of the egg shrivels up into a reddish
point and dies.”
“But how do these eggs manage to get through the winter without
freezing?” asked Louis. “Hens’ eggs or birds’ eggs would be good for
nothing after being left out-doors from autumn till spring.”
“That is true,” assented Uncle Paul; “nevertheless these minute germs
of future insect life seldom fail to hatch when warm weather returns.
From them come plant-lice like those on the roots of the vine. Each
new-born louse crawls down the natal vine, hunts around on the ground
until it finds a crack in the soil, and then makes its way through this
fissure to settle at last on a rootlet, into which it plunges its
sucker. At ease thenceforth beneath the surface of the ground and in
the bosom of abundance, it does not long remain alone. Close to its
fixed position it deposits its little heap of yellow eggs, whence there
quickly issues a new generation. In like manner each member of the
family surrounds itself with a family of its own; and so on by several
successive repetitions of the process until, from having but a single
occupant at first, a root speedily becomes covered with a legion of
destroyers. To this population of recent origin we must not forget to
add the older inhabitants that have passed the winter under ground and
have only waited for the return of the warm season to resume their own
laying of eggs on the roots of the vine.
“Let us recapitulate these singular ways of the phylloxera. The species
comprises three forms of insects, each having its own peculiar
structure, its manner of life, its separate function. The customary
animal unity is here a trinity: three different insects are grouped in
a single species.
“The sedentary members are wingless and live on the roots. All lay eggs
and are followed by several generations likewise capable of laying
eggs. Under the pricking of their collective suckers, numberless in the
aggregate, vineyards are ruined. There we have the formidable foe, the
ravager whose sucker, hardly visible to the naked eye, has already cost
us more than ten milliard francs.
“The migrating members are furnished with large wings. They live on the
leaves and lay each a small number of eggs in the down of the buds.
Like their sedentary kinsfolk, they all lay eggs. Their peculiar office
is to disseminate the race from one vineyard to another.
“The members endowed with sex come under the operation of the general
law: they are divided into male and female. Unprovided with wings,
sucker, or stomach, they wander over the vine without taking any
nourishment. Each mother lays a single egg, the winter egg, whence
issues in the spring a sedentary phylloxera, which makes its way down
to the roots, establishes itself there, and becomes the head and center
of a new colony.
“How contend against this foe which, by reason of its numbers and its
underground abode, defies our attempts to exterminate it? Three
principal methods are employed. In the lowlands the vineyards are
flooded and kept under a good depth of water throughout the winter.
This submersion causes the death of the phylloxera at the roots of the
plant. As a second method, through holes bored to the roots the soil is
injected with an asphyxiating fluid called sulphur of carbon, the fumes
of which instantly kill all insects that they reach. The difficulty is
to do a thorough job and leave no survivors. A third device is employed
by those who import from America certain wild vines much hardier than
our cultivated ones, but producing inferior fruit. These American
plants resist the attacks of the phylloxera, and continue to flourish
where our vines would succumb. On these wild stocks, as soon as they
are well rooted, are grafted our native vines, and thus is obtained a
grape-vine of two-fold quality, resisting by the hardy nature of its
root the phylloxera’s assaults, and bearing, on its engrafted shoots,
the incomparable fruit of our old vineyards.”
CHAPTER LIV
NOCTURNAL BIRDS OF PREY
“The brown owl, the horned owl, the barn-owl and other species of this
family, are known under the name of nocturnal birds of prey. They are
called birds of prey because they live on the small animals that they
catch, such as rats and mice, both those that infest our houses and
those that live in the fields. Owls are, among birds, what cats are
among quadrupeds,—the inveterate foes of all those small rodents of
which the mouse is our most familiar example.
“The French language has recognized this analogy in its term chat-huant
[7] (hooting cat) applied to a certain kind of owl. This bird is, in
some sort, a cat in its manner of living, a cat that flies and that
utters a long-drawn cry like a plaintive howl. It is nocturnal; in
other words, it keeps itself hidden by day in some obscure retreat,
whence it comes forth only at nightfall, to hunt in the twilight and
under the rays of the moon.
“Owls have eyes of remarkable size, round, and both in a frontal
position instead of being placed one on each side of the head. A broad
rim of fine feathers encircles each eye. The reason for their great
size is found in the bird’s nocturnal habits. Having to seek its food
by a very feeble light, it must, in order to see with any distinctness,
have eyes that admit as much light as possible; that is, eyes that open
very wide.
“But this wide-openness of the eyes, so advantageous by night, is a
serious inconvenience to the owl in the bright light of day. Dazzled,
blinded, by the sun’s rays, the bird of darkness keeps itself in hiding
and dares not venture forth; but if forced to do so, it observes the
utmost circumspection, flying with cautious hesitation and by short
stages. The other birds, those accustomed to broad daylight, come and
insult it at will. Robin redbreast and the tomtit are the first to pay
their compliments in this manner, and are followed by the chaffinch,
the jay, and many others.”
“And doesn’t the owl do anything to get even with them?” asked Jules.
“Very little,” replied his uncle. “Perched on a branch of some tree,
the night bird answers its aggressors by a grotesque balancing of its
body, turning its large head this way and that in a ridiculous fashion,
and rolling its eyes in bewildered alarm. Its menaces are vain: the
smallest and weakest birds are its boldest tormentors, pecking it and
pulling its feathers without its daring to defend itself.
“Because of its wide-open eyes the nocturnal bird of prey needs a
subdued light like that of early dawn and of evening dusk. It is,
therefore, at nightfall and at the first signs of daybreak that these
birds leave their retreats and seek their prey. At these hours their
hunt is a fruitful one, for they find the rats and mice, whether those
that lurk about our houses and barns or those that live in the field,
either fast asleep or on the point of going to sleep. Moonlight nights
are the most favorable for the nocturnal bird’s purposes. Such nights
are nights of plenty, affording opportunity for protracted hunting and
many captures.
“Let us follow the owl on its nocturnal expedition. The moment is
propitious, the air is calm, the moon shines. The bird leaves its
sylvan retreat; it skims over the open field, the meadow, the prairie;
it inspects the furrows where the field-mouse lurks, the long grass
where it burrows, the ruins of deserted buildings where both rats and
mice scamper about.
“Its flight is noiseless, its silent wing cleaving the air without the
faintest sound. It is careful not to give the alarm to its destined
victims. This noiseless flight it owes to the structure of its
feathers, which are silky and finely divided. Nothing betrays its
sudden coming, and the prey is seized without even suspecting the
enemy’s presence. An extraordinarily keen sense of hearing, on the
other hand, advises the bird of all that is going on in the
neighborhood. Its ears, large and deep, perceive the mere rustle of a
field-mouse in the grass.
“The prey is seized with two strong claws warmly clothed in feathers
clear down to the very nails. Each foot has four toes, of which three
ordinarily point forward, and one backward; but, by a privilege common
to nocturnal birds of prey, one of the anterior toes is movable and can
point backward, so that the claw becomes divided into two pairs of
equally powerful grippers when the bird wishes to seize, as in a vise,
the branch whereon it perches or the victim struggling to escape.
“A blow of the beak breaks the head of the captured rat. This beak is
short and hooked, and the two mandibles have great mobility, which
enables them, in striking against each other, to make a rapid clacking,
a demonstration by which the bird expresses anger or alarm.
“The mandibles open wide in the act of swallowing, revealing a mouth of
ample proportions and a throat of excessive width. The prey, which has
first been well kneaded by the claws, disappears down this throat,
bones and all. Nothing is left of the rat or the mouse, not even the
fur.
“Digestion completed, there remains in the stomach a confused mass of
skins turned inside out and still wearing their fur, and bones stripped
as clean as if they had been scraped with a knife. The bird then
proceeds to rid itself of this encumbrance of innutritious matter.
Grotesque retchings indicate the labor of this deliverance. Something
makes its way upward through the extended throat, the beak opens, and
the act is accomplished. A rounded mass falls to the ground, composed
of skins, bones, hair, scales—in fact, everything that has defied
digestion. All nocturnal birds of prey have this ignoble manner of
freeing the stomach: they vomit in globular form the residue of their
prey after the latter has been swallowed whole.”
CHAPTER LV
THE SMALLER BIRDS
“Almost all the smaller birds are helpful to us in protecting the
fruits of the earth from the ravages of insects. Their services deserve
to be recorded in a long and detailed history, but time for that is
lacking and we must confine ourselves to brief mention of a few of
these valiant caterpillar-destroyers.
“The titmouse, or tomtit, is a small bird full of life and showing a
petulant humor. Always in action, it flits from tree to tree, examines
the branches with minute particularity, perches on the swaying end of
the frailest twig, where it clings persistently even though hanging
head downward, accommodating itself to the oscillations of its flexible
support without once relaxing its clutch or ceasing its scrutiny of the
worm-infested buds, which it tears open in order to get at the enclosed
vermin and insect-eggs.
“It is calculated that a tomtit rids us of three hundred thousand of
these eggs every year. It has to supply the needs of a family seldom
equalled in size; but the support of twenty young ones, or even more,
is not too heavy a burden for this active bird to bear. With this
infant brood on its hands, it must give constant and careful inspection
to buds and to fissures in the bark, in order to catch larvæ, spiders,
caterpillars, little worms of all kinds, and thus find food for twenty
beaks incessantly agape with hunger at the bottom of the nest.
“Let us suppose the mother bird to arrive with a caterpillar. The nest
is immediately all in a tumult: twenty beaks are stretched wide open,
but only a single one receives the morsel, while nineteen are kept
waiting. The indefatigable mother flies off again, and when the
twentieth beak has at last been fed, the first has long since begun
again its importunate demands. What a multitude of worms such a brood
must consume!
“Whole families of birds devote themselves, as does the titmouse, to
this patient quest for insect eggs in the crevices of tree-trunks or
concealed in rolled-up leaves, for larvæ between the scales of buds and
in worm-holes in wood, and for insects hidden in cracks and crannies.
In this kind of hunt the bird does not have to chase its game and catch
it by superior swiftness of flight; it must simply know how to find it
in its lair. To this end it needs a keen eye and a slender beak; wings
play but a secondary part.
“But other species spend their energies in the free open-air chase:
they pursue their game on the wing, hunting for gnats, moths,
mosquitoes, and flying beetles. They must have a short beak, but one
that opens wide and snaps up unerringly insects on the wing, despite
the uncertainties of aërial flight; a beak in which the victim is
caught and held without any retardation of the bird’s swift course; in
short, a beak with a sticky lining which a tiny butterfly cannot so
much as graze with its wing and not become entangled. Above all, an
untiring and swift wing is necessary, one that does not flag in the
pursuit of game desperately putting forth its utmost efforts to escape,
and one that is not baffled by the tortuous course of a moth driven to
bay. A beak inordinately cleft and wings of extraordinary power—such,
in a word, should be the equipment of the bird whose hunting ground is
the vast expanse of the open air.
“These conditions are fulfilled in the highest degree in the swallow
and the martin, both of which hunt flying insects, pursuing them this
way and that, back and forth, ceaselessly and with a thousand subtle
tricks. They catch them in their wide-open and viscous gullet, and
continue their course without a moment’s pause.
“The bird that lives on grain and seeds, the granivorous bird, as it is
called, has a beak that is very wide at the base and adapted by its
strength to the opening of the hardest seeds. In this class are the
chaffinch, the greenfinch, the linnet, the goldfinch, and the swallow.
The bird that lives on insects, or the insectivorous bird, has a beak
that is fine and slender, in delicacy proportioned to the softness of
its prey. To this number belong the nightingale, the warbler, the
fallow-finch, and the wagtail. Agriculture has no better defenders
against the ravages of worms than these little birds with slender
beaks, voracious devourers as they are of larvæ and insects.
“But the granivorous birds have certain grave faults: some of them are
addicted to pilfering in the grain-fields and know how to get the wheat
out of the ear, and some even come boldly to the poultry-yard to share
with its inmates the oats thrown to them by the farmer’s wife. Others
prefer the juicy flesh of fruit, and know sooner than we when the
cherries are ripe and the pears mellow. Such failings, however, are
amply atoned for by services rendered. The granivores pick up in the
fields an infinite number of seeds of all sorts which, if left to
germinate, would infest our crops with weeds.
“To this rôle of weeder they add a second not less meritorious. Grain
and seeds are, it is true, their regular diet; but insects are to few
of them so despicable as to be refused when sufficiently plentiful and
easy to catch. Indeed, we can go still further in our commendation of
these birds: in their early days when, feeble and featherless, they
receive their nourishment by the beakful from their parents, many of
them are fed on insects.
“Let us take for example the house-sparrow. Here we have, it must be
admitted, an inveterate devourer of grain. He robs our dove-cotes and
poultry-yards, steals their food from the pigeons and the hens, and
anticipates the farmer in reaping the grain-crops near his house. Many
other misdeeds are to be reckoned against him. He plunders the
cherry-trees, commits petty larceny in the garden, plucks up sprouting
seeds, and regales himself on young lettuce and the first leaves of
green peas. But as soon as the season of insect-eggs opens, this
shameless pilferer becomes one of our most valuable helpers. Twenty
times an hour, at least, the mother and the father take turns in
bringing the beakful of food to their little ones; and each time the
bill of fare consists of a caterpillar, or an insect large enough to be
divided into quarters, or perhaps a fat larva, or it may be a
grasshopper, or some other kind of small game.
“In one week the young brood consumes about three thousand insects,
larvæ, caterpillars and worms of all species. There have been counted
in the immediate vicinity of a single nest of sparrows the remains of
seven hundred June-bugs, besides those of innumerable smaller insects.
That is the supply of food required for rearing only one brood. Let us
then, my children, wish well to all the little birds that deliver us
from that formidable ravager, the insect.”
CHAPTER LVI
BIRDS’ NESTS
“It is in the building of nests destined for the rearing of a family of
young ones that the bird shows in a remarkable way that wonderful
faculty which enables the little creature to accomplish, without
previous training, results that would seem to require the intervention
of reasoned experience.
“These adepts in bird-nest architecture have talents of the most varied
sort. There are diggers, who scoop out a hollow in the sand; miners,
who excavate a little cell to which a long and narrow passage gives
access; carpenters, who bore into the trunk of a worm-eaten tree;
masons, who work with mortar made of earth tempered with saliva;
basket-makers, who weave together small twigs and fine roots; tailors,
who with a filament of bark for thread and the beak for needle sew a
few leaves together into a cornet for holding the mattress on which the
young brood will rest; workers in felt, who make a fabric of down,
hair, or cotton, that rivals our own similar products; and builders of
fortresses, who protect their nest with an impenetrable thicket as a
rampart.
“The goldfinch, that pretty little red-headed bird which feeds on the
seeds of thistles, builds a wonderfully wrought nest in the fork of
some flexible branch. The outside is made of moss and the silky down of
thistle-seeds and dandelions, while the inside, artistically rounded,
is lined with a thick cushion of horse-hair, wool, and feathers.
“The chaffinch builds its nest in nearly the same way, but, more
mistrustful than the goldfinch, it covers the outside of its abode with
a layer of gray lichen which, merging with the lichen growing naturally
on the branch, serves to baffle the scrutiny of the bird-nest hunter.
“The window-swallow makes its nest in the corners of windows, under the
eaves of roofs, and in the shelter of cornices. Its building material
is fine earth, chiefly that left in little piles after its digestion by
earth-worms in fields and gardens. The swallow fetches it, a beakful at
a time, moistens it with a little viscous saliva to make it stick
together, and deposits it in courses, shaping the structure into a sort
of hemispherical bowl fastened to the wall and having a narrow mouth at
the top to allow the bird to squeeze through. Bits of straw embedded in
this masonry of earth serve to give it greater solidity. Finally, the
inside is upholstered with a quantity of fine feathers.
“The chimney-swallow chooses a similar situation for its nest and uses
the same building-materials, but the nest itself takes a different
form. Instead of a hemispherical structure entered by a very small
opening, it builds a cup-shaped nest, of no great depth and wide-open
at the top.
“Swallows like to live together in large numbers, so that their nests
are sometimes found touching one another in colonies of several
hundreds under the same cornice. Each pair recognizes unerringly its
own belongings and respects scrupulously the property of others, in
return for like respect paid to its own. There is among them a deep
sense of solidarity, and they render mutual aid with no less
intelligence than zeal.
“Sometimes it chances that a nest has hardly been finished when it
crumbles to pieces, the mortar used having been of poor quality, or
else the masons, with injudicious haste, having had too little patience
to let one course dry before laying another on top of it. At the news
of this mishap neighbors of both sexes hasten up to console the
unfortunates and to lend their aid in rebuilding. All apply themselves
to the task, fetching mortar of the first quality, and straws and
feathers, with such ardor and enthusiasm that in two days the nest is
completely rebuilt. Left to their own unaided efforts, the afflicted
pair would have needed a fortnight to repair the disaster.
“The golden oriole is one of the most beautiful birds of our clime.
About as large as the blackbird, it has plumage of a superb yellow,
except the wings, which are black. In building its nest it selects, in
some tall tree, a long and flexible bough with a fork at the end.
Between the two branches of this fork a hammock is woven for receiving
the nest. Strands of fine bark that has become shredded by long
exposure to wind and weather are used for this work of art. These
strands or cords pass from one side of the fork to the other, enlacing
them, crossing and recrossing, and thus forming a sort of pocket,
firmly fixed and securely hung.
“Broad blades of grass consolidate the structure. Then in this hammock
a mattress of the finest straw and having the form of an oval cup is
put together. The completed work bears some resemblance to those
elegant little wool-lined wicker baskets that are used as nests for
caged canaries.
“The long-tailed titmouse, remarkable for its excessive caudal
development, which constitutes more than half the total length of its
body, lives in the woods during the summer season, and comes into our
gardens and orchards only in winter. It is a small bird with a reddish
back and white breast. The stomach is tinged with red; the neck and
cheeks are white.
“Its nest is built sometimes in the fork of a high branch in a clump of
bushes, and sometimes in the dense underwood of a thicket, a few feet
from the ground; but it is most often attached to the trunk of a willow
or a poplar tree. Its shape is that of a very large cocoon, and its
entrance is at one side, about an inch from the top. On the outside it
is made of lichens like those that cover the tree, in order to blend
with the bark and deceive the eye of the passer-by. Fibers of wool
serve to hold all the parts securely together. To make the dome of the
nest rain-proof, it is formed of a sort of thick felt composed of bits
of moss and cobwebs. The inside resembles an oven with cup-shaped
bottom and very high top, and is furnished with a remarkably thick bed
of downy feathers, whereon repose from sixteen to twenty little birds,
arranged with careful order in the restricted space no larger, at the
most, than the hollow of one’s hand. By what miracle of parsimonious
economy do these twenty little ones with their mother manage to find
room for themselves in this tiny abode? And how in the world can tails
ever grow to such length there?
“The nest of the swinging titmouse is still more remarkable. In our
country this bird is hardly ever found except on the banks of the lower
Rhone. It hangs its nest very high, on the tip-end of some swaying
branch of a tree at the water-side, so that its brood is gently rocked
by the breeze sweeping over the river.”
“Why, I should think,” put in Emile, “there would be danger of the
young birds’ spilling out of such a swinging nest.”
“Not at all,” replied his uncle. “The shape of the nest provides
against that. It is a sort of oval purse about as large as a
wine-bottle, with a small opening at one side, near the top. This
opening is prolonged like the neck of a bottle and will at the utmost
admit one’s finger. To pass through so narrow an entrance, the
titmouse, small as it is, must stretch the elastic wall, which yields a
little and then contracts again. This purse, as I have called it, is
made of the cotton-like flock that comes from the ripening seeds of
poplars and willows in May. The titmouse gathers these bits of down and
weaves them together with a woof of wool and hemp. The fabric thus
obtained is not unlike the felt of a cheap hat.
“It would be useless to seek an explanation of the bird’s astonishing
success in manufacturing, with no implements but beak and claws, a
textile that man’s skilful hand, left to its own resources, would be
unable to produce; and this success the bird achieves with no previous
apprenticeship, without hesitation and without ever having seen the
thing done by others. At the very first trial the titmouse surpasses in
its art our weavers and fullers.
“The top of the nest includes in its thickness the end of the branch
from which it hangs, with the terminal twigs of that branch, which
serve as framework for the nest’s vaulted roof, while the foliage
projecting through the sides of the nest protects it with its shade.
Finally, to secure greater firmness of support, a cordage of wool and
hemp is passed around the branch and interlaced with the felt of the
nest. The inside of this hanging habitation is lined with down of the
finest quality from the poplar tree.
“Are you acquainted with the troglodyte or, as it is more commonly
called, the wren? It is the smallest of our birds, and it too is a
master in the art of nest-building. Clothed in reddish brown, with
drooping wing and upturned beak and tail, it is always frisking,
hopping, and twittering,—teederee, teeree, teeree. Every winter it
comes flying about our houses, frequenting the wood-pile, inspecting
holes in the wall, and prying into the densest thickets. At a distance
it might be mistaken for a small rat.
“In summer it lives in the pathless woods. There, under the shelter of
some big root that lies close to the ground and is covered with a thick
fleece of moss, it builds a nest patterned after that of the swinging
titmouse. Its materials are bits of moss, selected for the purpose of
making the nest undistinguishable in appearance from that to which it
is attached. The bird gathers these materials and works them into the
shape of a large, hollow ball with a very small opening on one side.
The interior is upholstered with feathers.
“The magpie fixes its dwelling in the top of some lofty tree whence, as
from an observatory, it can spy from afar the approaching enemy. At the
juncture of a number of branching twigs that offer adequate support it
plants its nest, constructed of interlacing flexible sticks with a
floor of tempered earth. Fine rootlets, blades of grass, and a few
tufts of down form the bedding for the prospective brood.
“So far there is nothing to differentiate the structure from ordinary
nests; but now we behold the exhibition of a special talent on the
magpie’s part. The entire nest, and more particularly its upper part,
is surrounded by a thick rampart, a sort of fortified enclosure
composed of thorny twigs securely intertwined. One would take the whole
thing for a shapeless mass of brushwood. Through this rampart, on the
side that is most strongly defended, an opening is left of just
sufficient size to admit of the mother’s entrance and exit. It is the
only door to the aërial fortress.
“Let us turn now to a bird that builds upon piling. It is a warbler of
large size, called the great sedge-warbler or river-thrush. It selects
a cluster of four or five reeds that project above the surface of a
pond, with their stalks rooted in the mud under the water and growing
near together. These slender piles, the tops of which the bird brings
into such proximity as may be desired and fastens with connecting
strands, are made to bear an interlacing of flexible materials, such as
rushes, bark-fibers, and long blades of grass. It is a basket-weaver’s
job, with a framework of reeds as a basis for the structure. Finally,
in this basket, which is made much longer than wide, is placed the nest
proper, a warm little bed of cotton-like down, spiders’ webs, and wool.
“But this abode resting on piles above the water is exposed to two
dangers,—the swaying of the reeds which, bent over by the wind, might
incline the nest so that it would spill its contents either of eggs or
of young birds; and secondly, the spring freshets, which might rise so
high as to submerge the nest. These dangers, however, have been
foreseen by the bird. The nest is very deep, and furthermore the edges
of the opening bend inward and form a parapet. In this way is avoided
the risk of a fall when the reeds that bear the nest are swayed by the
wind. Finally, since the sedge-warbler is at liberty to build her nest
at any desired height above the surface of the pond, she places it
always high enough to be beyond the reach of the rising water, even in
great floods. One suspects the bird of being able to foresee, months in
advance, the coming inundation; for she builds her nest at a greater or
less elevation according to the high-water mark destined later to be
reached by the surface of the pond.
“The cisticola is a small warbler very common in the marshes of
Camargue, at the mouth of the Rhone. Its nest is placed in the middle
of a cluster of grass and rushes, and takes the form of a purse with a
small round opening. Fine dry leaves form the bed on which the eggs
rest, while other and larger leaves are fixed all around it to form an
enclosure.
“For this work the bird turns tailor, cutting the leaves and lapping
them over one another. Along the border of each leaf it punches holes
with the point of its beak and through these holes it passes one or
more threads made of cobwebs and the down from certain plants. Its
distaff for holding the thread—namely, the beak—does not admit of using
very long strands; hence the needleful, so to speak, goes only twice
or, at most, three times from one leaf to the next one. But no matter;
the sewing is strong enough to fasten the whole into a sort of purse
which keeps out the rain.
“The orthotomus, or grass-warbler, a small bird of India, is an even
more skilful tailor, and in fact is commonly known as the tailor-bird.
It selects two large leaves, still living and attached to the branch on
which they grew. These are brought together, with their longer edges
touching, and are sewed border to border with strong cotton thread made
by the bird’s beak. The seams run only half the length of the leaves,
in such a manner that the two together, hanging down as they do, form a
conical sac with its mouth upward. In this sac the nest is placed,
hidden by its protecting envelope, which so blends with the rest of the
foliage that even after a person has once found the nest he can with
difficulty find it again.
“In South Africa there is a bird scarcely larger than our swallow and
known as the social republican from its living in large societies with
one nest in common. This nest, a sort of bird village, is shaped like
an enormous mushroom, spreading out all around the trunk of a tree,
which serves as its stalk, while the lower branches also furnish their
support. This colossal edifice is of such bulk and weight as to make a
wagon-load, and if one wishes to see the interior structure it must be
chopped to pieces with an axe. It is formed wholly of dry grass
arranged much like the thatch on our rustic roofs.
“Indeed, this structure, built at public expense by all the associated
birds, is nothing but a roof, a dome, destined to shelter the real
nests, which are attached to the inside of the thatched covering. Here
are to be found a multitude of round holes presenting all together
somewhat the appearance of a honeycomb. Each hole gives access to a
small cell, a veritable nest and the separate work of a single pair.
The grass roof, then, is built in common by the whole society, after
which each family provides for its exclusive use a little apartment
attached to the lower side of the roof. The number of inhabitants may
reach as high as a thousand.”
CHAPTER LVII
MIGRATION OF BIRDS
“At the approach of the cold season,” Uncle Paul resumed, in his
account of bird habits and bird peculiarities, “before winter clears
the fields of insects, covers the ponds with a coating of ice, and
whitens the landscape with snow, thus cutting off the food-supply
hitherto obtainable from the earth, many birds, especially those that
live on insects or frequent bodies of water and marshy meadows, take
leave of their native land and direct their course southward, where
they will find a warmer sun and a more assured supply of food.
“They take their departure, some in large flocks, others in small
groups, or even each one separately. With no guide other than an
irresistible impulse too mysterious for us to explain, they traverse by
successive stages immense tracts of land, cross seas, and bend their
course toward the countries of the south. Africa is the rendezvous of
our birds and of European birds in general.
“After the cold season has passed, with the first fine days of spring
the same birds return to the regions where they were born, making the
journey this time in the opposite direction, from south to north. They
take possession once more of their groves and forests, their rocks and
prairies, which they know how to find with an inconceivable accuracy.
There they build their nests, rear their young, and gain strength for
the coming journey; and upon the return of cold weather they go back
again to the lands of sunshine.
“These periodical journeys are called migrations, of which there are
two each year,—that of autumn, when the birds leave us and go
southward, and that of spring, when they fly northward and come back to
us. These semi-annual flittings take place all over the earth.
“The various species do not all fix upon the same time for their
migration, but each has its own calendar, from which it departs only
very slightly. Some start well in advance of the increasing chill and
the lessening abundance of food, while others do not leave their native
land until driven by actual necessity, when the cold has become severe.
Thus our martin flies away for Africa as early as the month of August,
whereas the chimney-swallow lingers until October or even November.
“The martins forsake our turrets and old walls, our steeples and
belfries, while the summer heat is still intense and the small flies on
which they feed are still abundant. It is not, then, any lowering of
temperature that drives them away, nor is it any lack of food that
hastens their departure; but they have a secret presentiment of the
change of season that is coming in a few weeks; a deep-seated unrest,
which they cannot overcome, warns them that the hour for their
departure is drawing near.
“If one desires to witness this anxiety that torments the bird when the
time for migrating arrives, he may do so by rearing in captivity a
migratory bird caught very young. The captive, though never having
lived with its kind or had any knowledge of their migratory habits, and
furthermore having been kept in a cage with no experience of cold or
hunger, nevertheless, when the season for flitting arrives, shows
agitation and mental distress, and tries to escape from its
prison—after remaining so quiet and contented up to that time. Some
inner voice—instinct we call it—says it is time to go, and the captive
is eager to be off. If the desire is thwarted, death follows.
“To tear oneself from beloved haunts to incur the fatigues and perils
of a long journey is undoubtedly a painful decision; yet the bird
courageously submits to the inevitable, but in the hope of coming back
again some day. The strong reassuring the weak, the older ones guiding
the young, the departing flock forms itself into a caravan and takes
wing for the south. The sea is crossed, the treacherous sea from which,
at long intervals, rises an island as halting-place. Many perish in the
crossing, many reach the goal worn with hunger and spent with fatigue.
“The day for starting on this momentous journey is decided upon in a
great assembly, toward the end of August for the window-swallow, and
considerably later, even as late as November, for the chimney-swallow.
When once the date has been fixed, the window-swallows gather together
daily for several days on the roofs of tall buildings. Every few
minutes small parties detach themselves from the general conclave and
circle about in the air with anxious cries, taking a parting look at
their native haunts, and paying them a last farewell. Then they return
to their places among their companions and join in noisy chatter on the
subject of their hopes and fears, all the while preparing themselves
for the distant expedition by a careful inspection of their plumage and
a final touch to one lustrous feather after another.
“After several repetitions of these farewells a plaintive twittering
announces the fateful hour. The moment has come, it is time to start.
The flock rises, the emigrants are off for the south. If one of them
has been marked with a red string around the claw in order to be
recognized, you may be sure you will see it come back the next spring
and take possession of its nest again with little cries of joy at
finding it intact and ready for occupancy after a few repairs.
“With their vigorous wings the duck and goose, in their wild state, are
ardent travelers. On a gray day in November, when there are signs of
snow, it is not unusual to see passing from north to south, at a great
height, birds arranged in single file, or in a double file meeting in a
point, like the two branches of the letter V. These birds are a flock
of either ducks or geese in the act of migrating.
“If the flock is of no great size, the birds composing it arrange
themselves in one continuous file, the beak of each following bird
touching the tail of the preceding, in order that the passage opened
through the air may not have time to close again. But if the flock is a
large one, two files of equal length are formed, which meet at an acute
angle, the front of the moving mass.
“This angular arrangement, of which we find examples in the ship’s
prow, the plowshare, the thin edge of a wedge, and a multitude of
utensils designed for cleavage, is the most favorable for pushing
through the mass of the air with the least fatigue. If in marshaling
their flying battalions the goose and the duck had taken counsel of the
engineer’s science, they could not have managed better. But they have
no need of others’ advice: instructed by their own instinct, they
utilized long before we did the principle of the wedge.
“Moreover, to divide among all the members of the flock the excess of
fatigue incurred by the file-leader in opening a passage through the
air by strength of wing, each in turn takes the post of honor, the
forward end of the single file or the point of the angle formed by the
double file. Its term of service ended, the bird at the head retires to
the rear to recuperate, and another leader takes its place. By this
equitable division of labor the fatigue does not prove excessive for
any one bird, and the flock leaves no stragglers behind.”
CHAPTER LVIII
CARRIER-PIGEONS
Resuming the subject of bird instinct as illustrated by the migratory
flock’s unerring precision in finding its way over thousands of miles
to a desired nesting-place, Uncle Paul continued as follows:
“How is it that so many thousands, even millions, of migrating birds
can direct their course through trackless space each to the particular
rock or tree or nest left behind six months before, when the yearly
removal was decided upon to some southern region a thousand miles or
more distant? How, for example, does the frail swallow manage to find
again, at the return of spring, its tiny abode in the north when it
retraces the long journey of the previous autumn? In order that we may
be sure it is the same swallow returned to the same nest we tie a
colored string, as I have said, around the bird’s claw; and, lo and
behold, when April comes, with it comes our swallow to its dwelling
under the eaves. It is indeed our identical bird and no other; it is
the very one that fashioned the nest of clay, cherished bit of private
property now so eagerly taken possession of once more. The owner’s
demonstrations of satisfaction and delight are convincing proof, even
were the bit of red thread not there to dispel all doubt.
“If the swallow is able to find its nest again upon returning in the
spring from the land of the negroes, still more will it be able to find
it after being removed merely from its native canton to the neighboring
one.
“A mother sitting on her eggs or feeding her young is taken, let us
suppose, put into a basket, and carried quickly to a spot twenty or
thirty leagues distant, where she is set free again. The surrounding
country is unfamiliar to her: she has never been there before. Of the
road over which she has just come she has not the slightest knowledge,
having traveled it in the darkness of a closed basket. No matter. With
only a moment’s hesitation she gets her bearings amid these strange
scenes and takes flight toward her nest as unerringly as if it were
possible to see the very roof under which repose her little ones. In a
few hours we shall find her back again on her nest.
“A like behavior under similar conditions might be witnessed in the
case of divers other birds noted for strength of wing and power of
sustained flight. They would return to their domicile in spite of the
distance to be traversed and the unfamiliarity of the intervening
country. Maternal love can accomplish wonders. In order to save her
eggs from a chill or her little ones from starving in her absence, the
mother-bird exercises a geographical skill as marvelous as that
displayed at the period of migration.”
“I have heard it said,” remarked Louis, “that the pigeon is very clever
at finding its way over long distances, and that it is used for
carrying letters from one place to another.”
“Yes,” replied Uncle Paul, “this aptitude for retracing the homeward
way over vast distances is shown to an extraordinary degree by some of
our domestic pigeons. Economizing all their strength for purposes of
sustained flight, they have retained the wild pigeon’s pointed wings,
sleek plumage, and symmetrical form. We call these birds
carrier-pigeons, a name well earned, as you will see from what I have
now to tell you.
“A pigeon having a brood of young is taken from the pigeon-house, put
into a closed basket, and transported a distance of a hundred, two
hundred leagues, or even further if you choose—from one end of France
to the other. There it is set free. It rises in the air, circles about
a few times as if to assure itself of the direction to be followed, and
then starts off in impetuous flight toward the quarter where
pigeon-house and young await its coming.
“Does the bird catch sight of the pigeon-house as it circles about in
the upper air? By no means; the distance is too great. Even should it
rise to the height of the clouds, or to still greater altitudes, where
moreover its wings could not sustain it, it would be unable to see its
home. On the journey to the point where it was released it has had no
passing glimpse of any object, shut up as it has been in the dark
basket. The region it now traverses it sees for the first time. Nothing
in the surrounding landscape is familiar, and yet its flight evinces
the assurance that comes from having a definite goal in view. With a
speed of about twenty leagues an hour it wings its way straight to the
journey’s end. If the distance is too great to be covered without
pause, halts are made here and there for food and rest; then the
journey is resumed, swift as an arrow’s flight. Finally, at the end of
some hours or days, according to the distance and the duration of the
halts, the bird reënters the pigeon-house with its beakful of food for
the waiting little ones.
“In serious situations the carrier-pigeon is a valuable messenger.
During the winter of that terrible year, 1870–71, when the German
hordes besieged Paris, no communication was possible by ordinary means
between the invested city and the rest of France, in arms to repel the
odious invader. With Paris rendered mute by its isolation, one might
have said that the heart of the country had ceased to beat. For
communication between those within and friends without, recourse was
had to balloons and pigeons.
“Certain persons of dauntless courage left Paris by balloon, choosing
especially the night-time for their departure in order to avoid
encounter by day. They carried with them despatches from Paris and a
number of carrier-pigeons. Over the enemy camps they went, to alight
somewhere, far or near, at the pleasure of the winds. Thus the
provinces received despatches, newspapers, and private letters from
Paris. The car of the balloon was loaded with all these.
“But how carry back to Paris despatches from the provinces? To leave a
city by balloon in any chance direction is not so very difficult; but
to return by balloon to the same city is practically impossible. The
balloon goes as the wind wills, not as its passengers would like to
have it go. To seek to return by the means employed in departing would
be to compromise everything by incurring the risk of landing in the
midst of the Prussian lines.
“The only remaining expedient was to use those incomparable aids, the
pigeons, which the aëronaut had taken with him on his departure.
Released, one at a time, with despatches enclosed in a quill and
fastened to the bird’s tail, they flew back over the German army to the
pigeon-house; they reëntered Paris and brought news of what was going
on in the provinces.
“Do not imagine that the winged messenger was able to transmit only a
few words or at most a few lines. It was not with a pen or on ordinary
paper that the despatches entrusted to the pigeons were written. By
ingenious methods and with unheard-of delicacy it was found possible to
obtain characters so fine and sheets of paper so thin that a roll of
these sheets weighing scarcely a gram and enclosed in a quill contained
as much reading matter as ten printed volumes. What a marvelous piece
of work, that package of letters fastened to the pigeon’s tail, that
quill transformed into a library in which thousands of persons—friends,
kinsfolk, statesmen—communicated their projects, their fears, their
hopes! In this manner the mail service was maintained during those
woeful times.”
CHAPTER LIX
SOME PREHISTORIC ANIMALS
“Fossil remains of all sorts of animals, from the largest to the
smallest, are found embedded in stone. There are lizards which, if
alive, would hardly find room enough to turn around in many of our
public squares, so monstrous is their size; tortoises with shell as
large as a small boat; fishes of strange formation; birds of a singular
character such as we no longer behold; and enormous quadrupeds that
would dwarf to insignificance our sturdy ox. All flying creatures of
the air, all walking and creeping animals of the earth, every form of
life swimming in the water, are represented in these fossil remains
found in the heart of our rocks, but of a shape and often of a size
very different from those of our living animals.
“These ancient creatures have never been seen alive by man, so far back
in the past is their period. After inhabiting the earth for a very long
time, they disappeared forever, to give place to other species. What
remains of them consists chiefly of bones, which from their hardness
and their mineral character offer the most resistance to the various
destructive agencies. With the sole aid of these bones science succeeds
in reconstructing the exact form of the animal. It also tells us what
the animal fed on and what were its habits. By a miracle of sagacity it
resuscitates, so to speak, the ancient, dislocated carcass, and makes
it live again to the mind’s eye.
“Fossil bones are commonly found embedded in stone quarried at
considerable depths; it needs the work of pick and chisel and hammer to
free them from the rock. How did they come to be there? In the same way
as shells. If the creature lived in the waters of a lake or of the sea,
the mud at the bottom covered the body after death. If it lived on
land, the floods swept away its carcass and bore it to the river, which
in turn carried it to lake or ocean. Later the lake dried up or the
ocean receded, and the hardened clay left behind became the stone
whence to-day are obtained the relics of prehistoric forms of animal
life.
“What, then, were these prehistoric forms of animal life that preceded
man? Regarding ourselves as related to the animals provided with bones,
a sort of inner framework sustaining the corporeal edifice, we may say
in a general way that there has been a gradual succession from lower to
higher in structure. First appeared the fishes, then came the reptiles,
next the birds, after them the quadrupeds, suckling their young, and
last of all man, placed above all the rest by his incomparable
endowments.
“Let us glance rapidly at some examples of the ancient denizens of land
and sea. Look at this picture. The back of the creature here
represented resembles a little, in its form and in its regular rows of
scales, the tail of a fish; but the front—to what can that be likened?
What is the meaning of those large bony plaques arranged side by side
like the squares in a tessellated pavement? The animal is armed with
coat of mail, perhaps to protect itself from the bite of an enemy.
“What is the purpose of those wing-like appendages that strike the
flanks? Of what use are those two short horns at the base of the
forehead? What sort of a creature can it be that thus singularly
combines in its structure the tail of a fish, the shell of a tortoise,
the featherless wings of a bird, and the nascent horns of a ram? You
will never guess the answer, so different is the creature from any that
are known to you. It is a fish, but such a fish as no frying-pan of
ours has ever had acquaintance with, nor does the ocean now hold any
more like it.
“It goes back to the earliest ages of the world, and is called the
pterichthys. Do not exclaim at this name, as strange to our ears as the
creature itself to our eyes. Translated into our tongue, it means a
winged fish. But did this fish of former ages really fly? Assuredly
not. It was too heavy, too massive, to admit of that. Its wings were
simply admirable fins for swimming.
“In the seas of our day there live certain fishes fitted for flying.
Their lateral fins, which are very long, open like large fans and
enable them to sustain themselves for some time in the air. Pressed too
hard by a pursuing foe, they escape by leaping out of the water and
flying over the waves, clearing a certain distance before plunging
again into the water, as they must when their fins begin to get dry and
to lose their suppleness. They are called flying fishes. Compare these
two pictures and you will see how greatly the present flying fish
differs from the ancient winged fish.
“And this other creature—what wild dream could have conceived such a
monstrosity? It has the head and neck of a plucked bird; and it also
has a bird’s beak, but an enormous one armed with pointed teeth in each
mandible. Its wings are those of a bat, one talon of each claw being
disproportionately elongated and serving as support to a wide membrane,
much as an umbrella-rib holds the stretched fabric of the cover. Its
other talons are free and are furnished with hooked nails.
“The hind legs and feet are those of the lizard. The body is covered
with fine scales, is marbled with touches of a darker color, and ends
in an abbreviated tail. Take away from this strange animal its bat’s
wings, its long neck and its bird’s head, and you will have something
closely resembling the lizard, the creature that basks in the sun on
old walls, or that other one, larger and all green, which gives us a
start when it scuttles away among the dead leaves or in the dense
growth of the hedge.”
“And was it a lizard, then, or a bird?” asked Emile.
“It was a reptile, certainly,” was the reply, “and it might be called a
sort of lizard. There were several species, varying from the size of a
lark to that of a crow. Like the bat, the animal left its retreat in
the hollow of rocks and came out at night to flutter awkwardly about in
the air by the aid of its wings of stretched skin. With its toothed
beak it snapped up in their flight immense dragon-flies, the chief
insects of that time. Its hunger appeased, it took its repose on the
ground, wings folded against its sides, body supported by the hind
legs; or else it hung down from the rocks, suspended by its claws. Its
name is pterodactyl, which means wing-fingered.
“Let us consider another of these prehistoric creatures. This time it
is a bird, and what a marvelous bird, too, my friends! Its beak, no
less monstrous than that of the pterodactyl, had likewise the two
mandibles armed with a ferocious-looking set of teeth. Pointed teeth in
the jaws of a reptile, such as a lizard, crocodile, or serpent, are
nothing extraordinary; but in a bird’s mouth, that is unheard-of.
To-day one would search in vain all over the earth for anything like
it. There are beaks of all shapes and sizes, there are short ones and
long ones, straight ones and crooked ones, strong ones and weak ones;
but all are toothless, as are the hen’s and the sparrow’s. What a
singular custom in the primitive bird, to adopt for beak the toothed
jaws of the reptile!
“And that is not all. This bird adopted also the reptile’s tail, but
covered it with feathers. Birds of the present day have a short, wide
rump, from which grow a dozen coarse feathers. The first bird in the
order of time had its tail composed of a long succession of little
bones, each supporting two feathers. Here is a picture of that tail
just as it was found in the rock where the strange creature left its
remains. The bird to which the tail belonged is called by the learned
an archæopteryx, or ancient winged animal.
“One more of these monsters, and that will suffice. The animal that you
see here is the mammoth, a sort of enormous shaggy elephant, so tall
that its back would have touched the ceiling in most of our great
halls. Its height was as much as six meters. By its side the ordinary
elephant, the largest of extant terrestrial animals, would look no
larger than a sheep beside an ox.
“Its tusks, which had a pronounced backward curve, measured four meters
in length and weighed as much as four hundred and eighty pounds each.
What must have been the strength of a colossus carrying between its
lips a weight of nine hundred pounds as easily as a cat carries the
hairs of its mustaches!
“Man was already in existence at the time of the mammoth. Armed with
sharp flint-stones and bone-pointed arrows, he made bold to attack the
enormous animal whose weight made the earth tremble. He hunted it in
the chase and feasted on its flesh. What a piece of game when the giant
fell into the deep ditch masked by a light covering of boughs and
foliage! The victim was then overwhelmed with masses of rock, after
which there was an interminable banquet for the whole tribe.
“Let us go no further, but merely say in conclusion that the animals of
to-day are not the same as those of former ages. Long before the
present species on land and in the sea, there gradually made their
appearance other very different forms of animal life, which have now
become extinct. Nowhere on the earth are there now living any creatures
like those that have left their fossil remains for our inspection.”
CHAPTER LX
THE ORIGIN OF COAL
“Coal is a fuel of inestimable value. By the heat which it develops in
burning it gives movement to divers machines. It makes the locomotive
move over the iron rails and the steamship traverse the ocean. With its
aid metals are worked, fabrics woven, pottery is baked, glassware
manufactured, newspapers and books are printed, tools are shaped, and
all sorts of instruments necessary to our daily activities are
produced. The arts and crafts have no more powerful auxiliary. If we
had to substitute the heat of wood for that of coal, our forests would
prove insufficient.
“What, then, is the origin of this combustible, which feeds an immense
industry and is the source of incalculable riches? Ordinarily a piece
of coal has no great interest for the eye. It is black, lustrous,
formless, friable, without any definite character to afford us
instruction. One can learn more from the fragments of refuse rejected
by the miner as too poor in carbon, fragments in which the
predominating element is a kind of dark stone that splits in sheets. In
these a surprise is lurking that will tell us the secret of coal.
“These laminate blocks, stone rather than coal, show us, on the slabs
that have just been separated by the blow of the hammer, various
wonderful designs in which we recognize without hesitation the imprint
or mold of some form of vegetation. There is no mistake about it; a
plant has left its remains there; we behold in very truth the leaf with
its subdivisions and its veins. It is all there, even to the minutest
detail. It is really the leaf minus the green color, for which is
substituted the black of the coal. We should not obtain a more exact
representation if we ourselves took the imprint of some sufficiently
firm leaf on a soft plaque of clay.
“Pending the time when some lucky chance shall bring you into the
neighborhood of a coal mine where you can obtain a laminate block that
you can split into sheets and thus discover for yourselves the
vegetable imprints there concealed, here is a picture that will show
you what these curious markings look like.
“What do you think of it? Have we not here what seems to be actual
leaves, and very elegant ones too? They are spread out with a care that
would appear to indicate the work of a painstaking human hand. Yes,
these are real leaves, but turned to carbon and firmly incrusted in
their bed of black rock.
“Similar imprints are found in great abundance in all coal mines.
Certain coal-deposits, several meters thick, are composed entirely of
them, the smallest chip that one splits off bearing on each face the
markings of foliage. The whole is nothing but an accumulation of leaves
and broken tree-trunks. An entire forest, heaped up in one pile, would
not present an equal mass. Thus it is demonstrated that in coal are
preserved the remains of ancient vegetation.
“During great floods the rivers of former ages swept away in enormous
masses the trees they had uprooted along the banks, together with the
foliage washed into the current by the heavy rains; then all this
refuse was deposited in the mud at the river’s mouth, or in some lake
or bay. Thus were amassed here and there, under the water, during a
long series of centuries, the remains of primitive forests.
“Fine clay became packed about these masses, molding itself with
delicate accuracy around even the smallest leaf; the weight of the
superimposed mud crushed the softened tree-trunks; a gradual decay
converted the whole into charcoal; and finally the ligneous mass became
a layer of coal. Later the waters changed their bed, driven elsewhere
by upheavals in the surface of the earth, and the previously inundated
bottom-lands became solid ground in which to-day we find coal under
massive strata of rock.
“Is it possible to distinguish the forms of plant-life whence has come
our coal? Yes, it is possible, so well preserved are the details of
that life in the products of our mines. Now an examination of the
imprints left to us in the laminæ or leaves of our stone book shows us
that the plant-life of those remote ages in which the coal was
accumulated bore not the least resemblance to that of our present
forests. And this difference was to be expected. The animal life has
changed; why, then, should the plant-life have remained unaltered?”
“Didn’t they have trees then like ours?” asked Jules.
“No,” replied his uncle; “we do not find in our coal mines any signs of
the existence of trees resembling those of our day. Nowhere in the
world, in fact, are there now to be seen any such forms of plant-life
as flourished so abundantly in those remote ages; or if any still exist
that are at all analogous, they must be sought in the islands of the
tropical seas. No vegetable growth of that coal epoch, whether tree or
bush or simple cluster of leaves, bore flowers. The splendors of the
corolla were not to appear until a later period.
“For the most part there were only tall stems or stalks, without
branches, of equal size from top to bottom, and furrowed with channels
or dotted with large points arranged in spiral lines. At the top a tuft
of enormous leaves balanced itself, the under surface of each leaf
bearing elongated or rounded swellings containing a fine brown dust,
each grain of which was a seed for the propagation of the plant.
“Plants that thus bear their seeds, or spores, in powdery masses on the
under side of the leaves are called ferns. A number of species flourish
in our part of the world. They are unpretentious plants, fond of shade
and coolness. Old damp walls, rocks that drip water drop by drop, the
darkest corners of our woods—these are the customary haunts of the
fern.
“A short underground stock and a sparse cluster of leaves, very
elegantly shaped, it is true, constitute our native ferns. Those of the
coal epoch were of a different pattern. Some of them displayed at the
top of a stem as tall as our poplars a cluster of leaves five or six
meters in length. They are called tree-ferns, and they contributed the
greater part of the coal-forming material.
“The accompanying illustration will give you an idea of what the
vegetation of that period must have looked like. What strange trees!
How different from our oaks and maples and hemlocks! The soil is a
liquid mud in which lie and rot the tree-trunks prostrated by the
weight of years; the air is sultry, moist, heavy, strongly impregnated
with a moldy smell; and the density of the foliage barely admits a few
sunbeams to flicker over the surface of the stagnant pools.
“Everywhere profound silence. No song of bird bursts forth from the
foliage of those tall fern-trees, for the bird is not yet in existence.
No foot of quadruped treads the ground, for the quadruped with its coat
of fur will not come until much later. Some lizards lurking in the
rock-fissures, some large dragon-flies at the water’s edge, some odious
scorpions under the heaps of dead leaves—that is all the animal-life to
be found in the forests that gave us our coal.”
CHAPTER LXI
THE FARMER’S HELPERS
“By ‘helpers’ I here mean those animals and birds that come to our aid,
though not subject to our care and protection, and make war on the
insects and divers other devourers that would soon get complete control
of our crops if we were left to our own resources for preventing their
excessive multiplication. What could man do against those voracious
hordes that annually propagate their kind at a rate defying
calculation? Would he have the patience, the skill, the keenness of
eyesight necessary for effective warfare upon the smallest of these
marauders when the June-bug, despite its size, mocks at our utmost
efforts to exterminate it? Would he undertake to examine all his
fields, a clod at a time, to inspect his grain, ear by ear, to
scrutinize his fruit trees, one leaf after another? For so prodigious a
task the combined efforts of the whole human race would not suffice.
The devouring hosts would eat us up, my friends, if we had no helpers
to come to our rescue, helpers endowed with a patience that nothing can
weary, an adroitness that baffles all wiles, a vigilance from which
there is no escape. To lie in wait for the enemy, to seek him in his
remotest retreats, to pursue him without pause or rest, and finally to
exterminate him, that is their sole concern, their incessant
preoccupation. They are implacable, pitiless; hunger urges them on,
both for their own sake and in behalf of their families. They live at
the expense of those that live at our expense; they are the enemies of
our enemies.
“As participants in this great work must be named the bat and the
hedge-hog, the owl, the martin, the swallow, and all the smaller birds,
the lizard, the adder, the frog, and the toad. Praise be to God who has
given us as protectors from that glutton, the insect, such birds as the
swallow and the warbler, the robin and the nightingale, the martin and
the starling. And yet these invaluable creatures, guardians of earth’s
bounty, a delight to the eye, a solace to the ear, have their homes
pillaged by the barbarous and stupid robber of birds’ nests. Praise be
to God who for the protection of our daily bread has given us the owl
and the toad, the hedge-hog and the bat, the adder, the lizard and the
mole. Nevertheless these useful creatures that come so valiantly to our
aid are cursed and calumniated, and we stupidly vent upon them our
loathing and hate.
“By what perversity are we, in general, impelled to destroy animals
whose coöperation is so much to our advantage? Nearly all our helpers
are persecuted. Their good will must be indomitable to make them bear
our ill treatment and not forsake our dwellings and fields, never to
return. The bat rids us of a host of enemies, and is nevertheless under
the ban; the mole clears the soil of vermin, and is likewise
proscribed; the hedge-hog wages war on vipers and cut-worms, and it too
is an outlaw; the owl and various other night birds are accomplished
rat-hunters, and they also are in disfavor; the adder, toad, and lizard
feed on the ravagers of our crops, and all the while we hold them in
abhorrence. They are ugly, we say, and without further reason we kill
them. But, blind slayers, the day will come when you will perceive that
you have been sacrificing your own defenders to an irrational
repugnance. You complain of rats, but you nail the owl to your door and
let its body dry in the sun as a hideous trophy; you cry out against
cut-worms, but you crush the mole every time your spade turns one up;
you disembowel the hedge-hog and set your dogs on him just for fun; you
bewail the ravages of moth and worm in your granaries, but if the bat
falls into your clutches it is seldom that you show him any mercy. Your
complaints go up to heaven, but all these willing helpers of yours you
treat as creatures accursed. Blind fools that you are, filled with an
insane desire to kill!
“Insect-eating birds are of immense importance to agriculture. They
divide among themselves the work to be done in field and hedge, meadow
and garden, forest and orchard, and wage unceasing warfare on every
species of vermin, a terrible tribe that would destroy our crops were
not more vigilant guardians than we continually on the watch—guardians
of far greater adroitness, of sharper eyesight, of more lasting
patience in their endless quest, and having nothing else to do. I am
not exaggerating, my little friends; without insect-eating birds famine
would decimate us. Who then, unless he be an idiot with a mania for
destruction, would dare touch the nests of birds that enliven the
country with their plumage and deliver us from the devouring scourge of
insects? But there are, nevertheless, bloodthirsty gamins who, if they
can manage to elude the school-master and play truant, find it a joyous
pastime to climb trees and explore hedges in order to rob birds’ nests
and slaughter the young. These good-for-nothings are under the
surveillance of the rural guard and liable to the utmost rigors of the
law, to the end that our crops may still be protected by the birds and
that our fields and orchards may continue to yield sheaves of grain and
baskets of fruit.
“Let us add a few words on the mode of life of these indispensable
collaborators. The bat feeds exclusively on insects, anything in that
class serving its purpose,—beetles with hard wing-sheaths,
spindle-shanked mosquitoes, graceful butterflies, plump-bellied moths
of all kinds, such as make havoc of our cereals, vineyards, fruit trees
and woolen stuffs, and those that come in the evening, attracted by the
lamplight, and singe their wings over the flame. Who shall say how many
insects are snapped up by the bats in their nightly tour of our
premises? The game is so small, the hunter’s appetite so insatiable!
“Note what takes place on a calm summer evening. Lured abroad by the
mild temperature of the twilight hours, a swarm of insects leave their
retreats and come out to play in the open air, to hunt for food, and to
mate, one with another. It is then that great night-moths fly abruptly
from flower to flower and plunge their long proboscis to the bottom of
the corolla, where they suck up the honey; it is then that the
mosquito, eager for human blood, sings its war-song in our ears and
chooses our tenderest spot for the insertion of its envenomed lancet;
and it is then that the June-bug quits the sheltering leaf, spreads its
resounding wings, and goes booming through the air in quest of its kin.
The gnats dance in joyous swarms which the least puff of wind disperses
like a column of smoke; the moths, their wings powdered with silver
dust and their antennæ displayed plume-fashion, indulge in frolicsome
gambols or go in search of favorable places for laying their eggs; the
little wood-gnawing beetles explore the wrinkled bark of old
tree-trunks; the wheat-moths rise in clouds from the ravaged grain and
take flight for fresh fields; and other night-flying insects flutter
about, alighting on grape-vines and fruit-trees, all busily searching
for food and shelter for their calamitous offspring.
“But suddenly this scene of jollity is intruded upon by a most
unwelcome kill-joy. The bat, with zig-zag course, flits hither and
thither, up and down, back and forth, untiring of wing, appearing and
disappearing, darting its head out this way and that, and each time
catching an insect in flight, which it immediately crushes and gobbles
up, sending it to its doom down a throat that opens wide from ear to
ear. It is famous hunting: gnats, beetles, moths, all are there in
plenty, and every once in a while a little cry of joy announces the
capture of an especially plump victim. As long as the fading twilight
admits of it, the ardent hunter continues in this way his work of
extermination. Stuffed to repletion at last, the bat regains its dark
and quiet retreat; but on the morrow, and every day thereafter
throughout the summer, the hunt will be resumed, always with the same
ardor, always at the cost of insects only. My children, respect the
bat, our helper in destroying the ravagers of our fields.”
CHAPTER LXII
THE FARMER’S HELPERS
(Continued)
“The hedge-hog’s diet consists especially of insects. The lowest order
of vermin is disdained by him as too small, but a June-bug larva or a
fat-bellied cricket is a capital prize, and when these are not too
deeply buried he burrows with claws and snout to unearth them. All
night long he goes prowling around, routing out and crunching a goodly
number of our enemies, without doing any appreciable harm himself.
“Listen now to what I am going to relate to you from the book of a
learned observer. ‘I had in a box,’ he says, ‘a female hedge-hog with
her sucklings; and I added to the occupants of the box a vigorous
viper, which coiled itself up in one corner. The hedge-hog slowly
approached and smelt of the reptile, whereupon the latter raised its
head and put itself on guard, showing the while its venomous fangs. For
a moment the aggressor recoiled, but only to resume the offensive
immediately after and with no sign of fear. The viper then bit the
animal on the end of its snout. The hedge-hog licked its bleeding
wound, and in doing so received a second bite on the tongue without
suffering itself to be at all intimidated. Finally it seized the
serpent by the middle of its body, and the two adversaries rolled
together on the floor in a furious struggle, the quadruped grunting and
snorting, the reptile hissing and making repeated use of its fangs.
Suddenly the hedge-hog seized its antagonist’s head and crunched it
between its teeth, after which, without the least sign of perturbation,
it proceeded to devour the forward half of the body. That done, it
returned to the opposite corner of the box and, lying on its side,
calmly began to suckle its young. On the morrow it ate the rest of the
viper. The same experiment was several times repeated, with an interval
of some days between each repetition and the next, but the issue was
always the same: in spite of wounds that set its snout to bleeding, the
hedge-hog invariably finished by devouring the reptile, and neither the
mother nor her young showed any ill effects from the experience.’
“It is to be assumed that the hedge-hog has not received the gift of
withstanding the venom of reptiles only to leave that gift unemployed.
The animal is evidently intended to find its chief pleasure in haunting
the places frequented by the viper; in its nightly rounds among the
underbrush it must often catch the lurking serpent and make short work
of the venomous creature. What valuable service it must render in
regions infested by this dangerous reptile! And yet man is the
hedge-hog’s inveterate foe, showering it with maledictions and treating
it as an unclean beast good for nothing except perhaps to arouse the
fury of dogs, which have to beware of its bristling back. Do not, my
children, imitate this evil example, but respect the hedge-hog for
ridding you of the cut-worm and the viper.
“Now as to the mole, what does it eat? The best way to decide the
question of an animal’s diet is to examine the contents of its stomach.
Let us, then, open the mole’s stomach and see for ourselves. Sometimes
it is found to contain red fragments of the common earth-worm;
sometimes a hash of beetles, recognizable from the tough remains that
have resisted digestion, such as bits of claws and wing-sheaths;
sometimes, again, and oftener than not, a marmalade of larvæ,
especially those of the June-bug, with their distinctive signs like the
mandibles and the hard casing of the head. One finds, in short, a
little of every sort of game haunting the soil,—polypods and millepeds,
insects and caterpillars, moths in the chrysalis, underground worms and
nymphs, and so on; but the minutest scrutiny fails to discover a single
particle of vegetable matter.
“The mole, then, is exclusively carnivorous, and furthermore it has a
monstrous appetite, a perfectly insatiable stomach that in twelve hours
demands a quantity of food equal to the animal’s weight. The mole’s
existence is one gluttonous frenzy, ever renewing itself, never
appeased; a few hours’ abstinence suffices to kill the creature. To
still the anguish of that stomach, which is no sooner stuffed with food
than it is emptied again, what can the animal count upon? On the grubs
living in the ground, and especially on those of the June-bug, tender
and fat. It is a small creature for supplying the wants of such an
appetite, but its numbers make up for its littleness. What a massacre
of worms, then, must not the mole be credited with in the season when
worms abound! Scarcely is one meal finished before another begins, and
at each repast the worms must be gobbled up by the dozen. To clear a
field of these formidable ravagers the farmer has no helper equal to
the mole. The only regret is that to reach the vermin on which the
animal lives, it has to burrow among the roots where they have their
haunts. Many roots that lie in the way are necessarily ruptured in this
work; plants are broken off and destroyed; and, finally, the little
piles of earth, or mole-hills, heaped up by the animal in the course of
its excavations, impede the reaper when harvest-time comes around.
Never mind: the worms would have caused much more serious damage, and
to get rid of them there is nothing like this ravenous insect-hunter.
Therefore, children, never molest the mole, the protector of our crops.
“The toad is harmless, but that is not enough to commend the creature
to our attention. It too is a helper of great worth, a greedy devourer
of slugs, beetles, larvæ, and every sort of vermin. Discreetly
withdrawn by day under the cool cover of a stone in some obscure hole,
it leaves its retreat at nightfall to make its regular rounds,
propelling itself, hoppity-hop, on its ample stomach. Here is a slug on
its way to the lettuce-plants; yonder is a cricket chirping at the
entrance to its hole; and over there a June-bug is laying its eggs in
the ground. Master toad comes along in circumspect fashion, opens his
cavernous mouth, and in three gulps swallows them all with a gurgle of
satisfaction. Oh, but that was good! Now for some more of the same
sort.
“He continues on his rounds, and when dawn begins to glimmer in the
east what kind of a hodge-podge of variegated vermin must there not be
in the glutton’s capacious maw? Yet they kill this useful
creature—stone it to death because, forsooth, it is not so handsome as
it might be. My children, may you never be guilty of such cruelty, such
foolish and mischievous cruelty! Never stone the toad, for in doing so
you would be robbing the fields of a vigilant guardian. Let the poor
creature perform in peace its appointed task as destroyer of worms and
insects.
“Finally, and not least of all, must be mentioned the various birds,
chiefly the little birds of our fields and farm-yards, that help the
farmer by devouring harmful insects and the seeds of wild grasses and
intrusive weeds. These indefatigable assistants, however, we have
already discussed, and we have gratefully acknowledged our indebtedness
to them. No more, then, need be said about them at present, except in
the way of renewed admonition never to molest them, never to rob their
nests; for they are our friends and benefactors.”
FINIS
NOTES
[1] Laundry starch is now obtained chiefly from rice and from
pulse.—Translator.
[2] The author is not quite accurate here. Franklin was, as he tells
us, “the youngest son, and the youngest child but two.”—Translator.
[3] The old fashioned loaf-sugar is here meant.—Translator.
[4] This is inconsistent with what Uncle Paul stated two paragraphs
above. He should have said here that the lily has but one floral
envelope.—Translator.
[5] In English this transfer of a bud is commonly called
“budding.”—Translator.
[6] The author does not, either here or later, distinguish by name, as
might have been done, between butterflies and moths. The latter fly
mostly in the evening or at night.—Translator.
[7] The corresponding English term is “screech-owl.”—Translator.
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