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Title: Marvels of Pond-life - A Year's Microscopic Recreations
Author: Slack, Henry J.
Language: English
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MARVELS OF POND-LIFE
A YEAR'S MICROSCOPIC RECREATIONS
AMONG THE
POLYPS, INFUSORIA, ROTIFERS, WATER-BEARS, AND POLYZOA.
BY
HENRY J. SLACK, F.G.S.,
SECRETARY TO THE ROYAL MICROSCOPICAL SOCIETY;
AUTHOR OF
'THE PHILOSOPHY OF PROGRESS IN HUMAN AFFAIRS,' ETC. ETC.
_SECOND EDITION._
ILLUSTRATED WITH COLOURED PLATES AND NUMEROUS
WOOD ENGRAVINGS.
LONDON:
GROOMBRIDGE AND SONS,
5, PATERNOSTER ROW.
MDCCCLXXI.
PRINTED BY J. E. ADLARD,
BARTHOLOMEW CLOSE.
INTRODUCTION.
As this little book is intended to be no more than an introduction to an
agreeable branch of microscopical study, it is to be hoped it will not
require a formal preface; but a few words may be convenient to indicate
its scope and purpose.
The common experience of all microscopists confirms the assertion made
by Dr. Goring, that the most fascinating objects are living creatures of
sufficient dimensions to be easily understood with moderate
magnification; and in no way can objects of this description be so
readily obtained, as by devoting an occasional hour to the examination
of the little ponds which are accessible from almost any situation. A
complete volume of pond lore would not only be a bulky book--much bigger
than the aldermanic tomes which it is the fashion to call "Manuals,"
although the great stone fists in the British Museum would be required
to grasp them comfortably,--but its composition would overtask all the
philosophers of our day. In good truth, a tea-spoonful of water from a
prolific locality often contains a variety of living forms, every one of
which demands a profound and patient study, if we would know but a few
things concerning it.
To man, then, is a vast and a minute. Our minds ache at the
contemplation of astronomical immensities, and we are apt to see the
boundless only in prodigious masses, countless numbers, and
immeasurable spaces. The Creative Mind knows no such limitations; and
the microscope shows us that, whether the field of nature's operation be
what to our apprehension is great or small, there is no limit to the
exhibition of marvellous skill. If the "undevout astronomer" be "mad,"
the undevout microscopist must be still more so, for if the matter be
judged by human sense, the skill is greater as the operation is more
minute; and not the sun itself, nor the central orb round which he
revolves, with all his attendant worlds, can furnish sublimer objects of
contemplation, than the miraculous assemblage of forces which make up
the life of the smallest creature that the microscope reveals.
There is an irresistible charm in the effort to trace _beginnings_ in
nature. We know that we can never succeed; that each discovery, which
conducts back towards some elementary law or principle, only indicates
how much still lies behind it: but the geologist nevertheless loves to
search out the first or oldest traces of life upon our globe; and so the
microscopist delights to view the simplest exhibitions of structures and
faculties, which reach their completion in the frame and mind of man.
That one great plan runs through the whole universe is now an
universally accepted truth, and when applied to physiology and natural
history, it leads to most important results.
The researches of recent philosophers have shown us that nature cannot
be understood by studying the parts of animals with reference merely to
their utility in the economy of the creature to which they belong. We
do, indeed, find an admirable correspondence between structures and the
services they perform; but every object in creation, and every part of
it, is in harmonious relation to some grand design, and exhibits a
conformity to some general mode of operation, or some general
disposition and direction of forces, which secures the existence of the
individual or the species, and at the same time works out the most
majestic schemes. Microscopic researches, such as are within the reach
of millions, offer many of the most beautiful illustrations of these
truths; and although the following pages are confined to such objects as
are easily obtainable from ponds, and relate almost exclusively to the
Infusoria, the Rotifers, the Polyps, and the Polyzoa, it is hoped that
they will assist in associating a few of the highly suggestive
reasonings of science, with one of the most pleasurable recreations that
human ingenuity has devised.
After a preliminary chapter, which is intended to assist the young
microscopist in some technical matters, that could not be conveniently
introduced into the text, the observations are distributed in chapters,
corresponding with the twelve calendar months. This arrangement was
suggested by the author's diary of operations for the year 1860, and
although it by no means follows that the months in which particular
creatures were then discovered, will be those in which they will be most
readily found in other years, it was thought advantageous to give a real
account of an actual period of microscopic work, and also that the plan
would facilitate a departure from the dry manner of a technical
treatise. The index will enable any one to use the book for the purpose
of reference, and it will be observed that the first chapter in which
any member of a group of creatures is introduced, is that in which a
general description of the class is given. The illustrations are taken
from drawings made by the wife of the author from the actual objects,
with the exception of a few instances, in which the authority is
acknowledged. The sketches were made _especially for beginners_, and the
rule followed, was not to introduce any details that could not be seen
at one focus, and with the simplest means: more elaborate
representations, though of the highest value to advanced students, are
bewildering at the commencement.
The ponds referred to are all either close to, or within a moderate
distance of, London;[1] but similar objects will in all probability be
obtained from any ponds similarly situated, and the descriptions and
directions given for the capture of the minute prey will be found
generally applicable. Care has been taken throughout to explain the most
convenient methods of examining the objects, and although verbal
descriptions are poor substitutes for the teachings of experience, it is
hoped that those here given will remove some difficulties from a pursuit
that no intelligent person can enter upon without pleasure, or consent
to abandon when its elementary difficulties have been mastered, and the
boundless fields of discovery are opened to view. Let not the novice be
startled at the word "discovery." It is true that few are likely to
arrive at new principles or facts which will inscribe their names upon
the roll of fame; but no one of ordinary powers can look at living
objects with any considerable perseverance, without seeing much that has
never been recorded, and which is nevertheless worthy of note; and when
the mind, by its own exertions, first arrives at a knowledge of new
truth, an emotion is felt akin to that which more than recompenses the
profoundest philosopher for all his toil.
[1] Many are now (1871) destroyed by the progress of building.
CONTENTS.
CHAPTER I.
MICROSCOPES AND THEIR MANAGEMENT.
Powers that are most serviceable--Estimated by Focal
length--Length of Body of Microscope and its Effects--Popular
Errors about Great Magnification--Modes of Stating Magnifying
Power--use of an "Erector"--Power of various Objectives with
different Eye-pieces--Examination of Surface Markings--Methods
of Illumination--Direct and Oblique Light--Stage
Aperture--Dark-ground Illumination--Mode of Softening
Light--Microscope Lamps--Care of the Eyes
CHAPTER II.
JANUARY.
Visit to the Ponds--Confervæ--Spirogyra
quinina--Vorticella--Common Rotifer--Three Divisions of
Infusoria--Phytozoa--Protozoa--Rotifera--Tardigrada--Meaning of
these Terms--Euglenæ--Distinction between Animals and
Vegetables--Description of Vorticellæ--Dark-ground
Illumination--Modes of producing it--The Nucleus of the
Vorticella--Methods of Reproduction--Ciliated
Protozoa--Wheel-bearers or Rotifers--Their Structure--The Common
Rotifer--The young Rotifer seen inside the old one--an Internal
Nursery--"Differentiation" and "Specialization"--Bisexuality of
Rotifers--Their Zoological Position--Diversities in their
Appearance--Structure of their Gizzard--Description of Rotifers
CHAPTER III.
FEBRUARY.
Visit to Hampstead--Small
ponds--Water-Fleas--Water-Beetle--Snails--Polyps--Hydra
viridis--The Dipping-tube--A Glass Cell--The Hydra and its
Prey--Chydorus Sphæricus and Canthocamptus, or Friends and their
Escapes--Cothurnia--Polyp Buds--Catching Polyps--Mode of Viewing
Them--Structure of Polyps--Sarcode--Polyps Stimulated by
Light--Are they Conscious?--Tentacles and Poison
Threads--Paramecium--Trachelius--Motions of Animalcules, whether
Automatic or directed by a Will--Their Restless Character
CHAPTER IV.
MARCH.
Paramecia--Effects of Sunlight--Pterodina patina--Curious
Tail--Use of a Compressorium--Internal Structure of
Pterodina--Metopidia--Trichodina
pediculus--Cothurnia--Salpina--Its Three-sided Box--Protrusion
of its Gizzard Mouth
CHAPTER V.
APRIL.
The Beautiful Floscule--Mode of Seeking for Tubicolar
Rotifers--Mode of Illuminating the Floscule--Difficulty of
seeing the Transparent Tube--Protrusion of Long
Hairs--Lobes--Gizzard--Hairy Lobes of Floscule not Rotatory
Organs--Glass Troughs--Their Construction and Use--Movement of
Globules in Lobes of Floscule--Chætonotus larus--Its mode of
Swimming--Coleps hirtus--Devourer of Dead Entomostraca--Dead
Rotifer and Vibriones--Theories of Fermentation and
Putrefaction--Euplotes and Stylonichia--Fecundity of Stylonichia
CHAPTER VI.
MAY.
Floscularia cornuta--Euchlanis triquetra--Melicerta ringens--Its
Powers as Brickmaker, Architect, and Mason--Mode of Viewing the
Melicerta--Use of Glass Cell--Habits of Melicerta--Curious
Attitudes--Leave their Tubes at
Death--Carchesium--Epistylis--Their Elegant Tree Forms--A
Parasytic Epistylis like the "Old Man of the Sea"--Halteria and
its Leaps--Aspidisca lynceus
CHAPTER VII.
JUNE AND JULY.
Lindia torulosa--OEcistes crystallinus--A Professor of
Deportment on Stilts--Philodina--Changes of Form and
Habits--Structure of Gizzard in Philodina Family--Mr. Gosse's
Description--Motions of Rotifers--Indications of a Will--Remarks
on the Motions of Lower Creatures--Various Theories--Possibility
of Reason--Reflex Actions--Brain of Insects--Consensual
Actions--Applications of Physiological Reasoning to the
Movements of Rotifers and Animalcules
CHAPTER VIII.
AUGUST.
Mud Coloured by Worms--Their Retreat at Alarm--A Country
Duck-Pond--Contents of its Scum--Cryptomonads--Their Means of
Locomotion--A Triarthra (Three-limbed Rotifer)--The Brachion or
Pitcher Rotifer--Its Striking Form--Enormous Gizzard--Ciliary
Motion inside this Creature--Large Eye and Brain--Powerful
Tail--Its Functions--Eggs
CHAPTER IX.
SEPTEMBER.
Microscopic Value of Little Pools--Curious Facts in Appearance
and Disappearance of Animalcules and Rotifers--Mode of
Preserving them in a Glass Jar--Fragments of Melicerta
Tube--Peculiar Shape of Pellets--Amphileptus--Scaridium
longicaudum--A Long-tailed Rotifer--Stephanoceros Eichornii--A
Splendid Rotifer--Its Gelatinous Bottle--Its Crown of
Tentacles--Retreats on Alarm--Illumination Requisite to see its
Beauties--Its Greediness--Richly-coloured Food--Nervous Ganglia
CHAPTER X.
OCTOBER.
Stentors and Stephanoceri--Description of Stentors--Mode of
viewing them--Their Abundance--Social Habits--Solitary Stentors
living in Gelatinous Caves--Propagation by Divers
Modes--Cephalosiphon limnias--A Group of Vaginicolæ--Changes of
Shape--A Bubble-blowing Vorticella
CHAPTER XI.
NOVEMBER.
Characteristics of the Polyzoa--Details of Structure according
to Allman--Plumatella repens--Its Great Beauty under proper
Illumination--Its Tentacles and their Cilia--The Mouth and its
Guard or Epistome--Intestinal Tube--How it swallowed a Rotifer,
and what happened--Curiosities of Digestion--Are the Tentacles
capable of Stinging?--Resting Eggs, or "Statoblasts"--Tube of
Plumatella--Its Muscular Fibres--Physiological Importance of
their Structure
CHAPTER XII.
DECEMBER.
Microscopic Hunting in Winter--Water-Bears, or Tardigrada--Their
Comical Behaviour--Mode of viewing them--Singular
Gizzard--Wenham's Compressorium--Achromatic Condenser--Mouth of
the Water-Bear--Water-Bears' Exposure to Heat--Soluble
Albumen--Physiological and Chemical Reasons why they are not
killed by Heating or Drying--The Trachelius ovum--Mode of
Swimming--Method of Viewing--By Dark-ground
Illumination--Curious Digestive Tube with
Branches--Multiplication by Division--Change of Form immediately
following this Process--subsequent Appearances
CHAPTER XIII.
CONCLUSION.--Remarks on Classification, &c.
MARVELS OF POND-LIFE.
CHAPTER I.
PLAIN HINTS ON MICROSCOPES AND THEIR MANAGEMENT.
Powers that are most serviceable--Estimated by focal
length--Length of body of microscope and its effects--Popular
errors about great magnification--Modes of stating magnified
power--Use of an "Erector"--Power of various objectives with
different eye-pieces--Examination of surface markings--Methods
of illumination--Direct and oblique light--Stage aperture--Dark
ground illumination--Mode of softening light--Microscope
lamps--Care of the eyes.
The microscope is rapidly becoming the companion of every intelligent
family that can afford its purchase, and, thanks to the skill of our
opticians, instruments which can be made to answer the majority of
purposes may be purchased for three or four guineas, while even those
whose price is counted in shillings are by no means to be despised. The
most eminent English makers, Wales, and Tolles, in America, and
Hartnack, in Paris, occupy the first rank, while the average productions
of respectable houses exhibit so high a degree of excellence as to make
comparisons invidious. We shall not, therefore, indulge in the praises
of particular firms, but simply recommend any reader entering upon
microscopic study to procure an achromatic instrument, if it can be
afforded, and having at least two powers, one with a focus of an inch or
two thirds of an inch, and the other of half or a quarter. Cheap
microscopes have usually only one eye-piece, those of a better class
have two, and the best are furnished with three, or even more.
The magnifying power of a compound microscope depends upon the focal
length of the object-glass (or glass nearest the object), upon the
length of the tube, and the power of the eye-piece. With regard to
object-glasses, those of shortest focal length have the highest powers,
and the longest eye-pieces have the lowest powers. The body of a
microscope, or principal tube of which it is composed, is, in the best
instruments, about nine inches long, and a draw tube, capable of being
extended six inches more, is frequently useful. From simple optical
principles, the longer the tube the higher the power obtained with the
same object-glass; but only object-glasses of very perfect construction
will bear the enlargement of their own imperfections, which results from
the use of long tubes; and consequently for cheap instruments the
opticians often limit the length of the tube, to suit the capacity of
the object-glasses they can afford to give for the money. Such
microscopes may be good enough for the generality of purposes, but they
do not, with glasses of given focal length, afford the same magnifying
power as is done by instruments of better construction. The best and
most expensive glasses will not only bear long tubes, but also
eye-pieces of high power, without any practical diminution of the
accuracy of their operation, and this is a great convenience in natural
history investigations. To obtain it, however, requires such perfection
of workmanship as to be incompatible with cheapness. An experienced
operator will not be satisfied without having an object-glass at least
as high as a quarter, that will bear a deep eye-piece, but beginners are
seldom successful with a higher power than one of half-inch focus, or
thereabouts, and before trying this, they should familiarise themselves
with the use of one with an inch focus.
It is a popular error to suppose that enormous magnification is always
an advantage, and that a microscope is valuable because it makes a flea
look as big as a cat or a camel. The writer has often smiled at the
exclamations of casual visitors, who have been pleased with his
microscopic efforts to entertain them. "Dear me, what a wonderful
instrument; it must be immensely powerful;" and so forth. These
ejaculations have often followed the use of a low power, and their
authors have been astonished at receiving the explanation that the best
microscope is that which will show the most with the least
magnification, and that accuracy of definition, not mere increase of
bulk, is the great thing needful.
Scientific men always compute the apparent enlargement of the object by
_one_ dimension only. Thus, supposing an object one hundredth of an inch
square were magnified so as to appear one inch square, it would, in
scientific parlance, be magnified to "one hundred diameters," or one
hundred linear; and the figures 100 would be appended to any drawing
which might be made from it. It is, however, obvious that the length is
magnified as well as the breadth; and hence the magnification of the
whole surface, in the instance specified, would be one hundred times one
hundred, or ten thousand: and this is the way in which magnification is
popularly stated. A few moments' consideration will show that the
scientific method is that which most readily affords information. Any
one can instantly comprehend the fact of an object being made to look
ten times its real length; but if told that it is magnified a hundred
times, he does not know what this really means, until he has gone
through the process of finding the square root of a hundred, and learnt
that a hundredfold magnification means a tenfold magnification of each
superficial dimension. If told, for example, that a hair is magnified
six hundred diameters, the knowledge is at once conveyed that it looks
six hundred times as broad as it is; but a statement that the same hair
is magnified three hundred and sixty thousand times, only excites a
gasping sensation of wonder, until it is ascertained by calculation that
the big figures only mean what the little figures express. In these
pages the scientific plan will always be followed.
If expense is not an object, a binocular instrument should be purchased,
and it is well to be provided with an object-glass as low as three or
even four inches focus, which will allow the whole of objects having the
diameter of half an inch or more to be seen at once. Such a low power
is exceedingly well adapted for the examination of living insects, or of
the exquisite preparations of entire insects, which can now be had of
all opticians. Microscopes which have a draw tube can be furnished with
an _erector_, an instrument so called because it erects the images,
which the microscope has turned upside down, through the crossing of the
rays. This is very convenient for making dissections under the
instrument; and it also gives us the means of reducing the magnifying
power of an object-glass, and thus obtaining a larger field. The erector
is affixed to the end of the draw tube, and by pulling it out, or
thrusting it in, the rays from the object-glass are intercepted at
different distances, and various degrees of power obtained.
A binocular microscope is most useful with low powers from two thirds
upwards. A new form, devised by Mr. Stephenson, acts as an erector, and
is very valuable for dissections. It works with high powers.
Beginners will be glad to know how to obtain the magnifying power which
different objects require, and it may be stated that, with a full-sized
microscope, a two-inch object-glass magnifies about twenty-five
diameters with the lowest eye-piece; a one-inch object-glass, or two
thirds, from fifty to sixty diameters; a half-inch about one hundred; a
quarter-inch about two hundred. The use of deeper eye-pieces adds very
considerably to the power, but in proportions which differ with
different makers. One instrument used by the writer has three
eye-pieces, giving with a two thirds object-glass powers of sixty one
hundred and five, and one hundred and eighty respectively; and with a
fifth two hundred and forty, four hundred and thirty, and seven hundred
and twenty, which can be augmented by the use of a draw tube.
It has been well observed that the illumination of objects is quite as
important as the glasses that are employed, and the most experienced
microscopists have never done learning in this matter. Most microscopes
are furnished with two mirrors beneath the stage, one plane and one
concave. The first will throw a few parallel rays through any
transparent object properly placed, and the latter causes a number of
rays to converge, producing a more powerful effect. The first is usually
used in daylight, when the instrument is near a window (one with a north
aspect, out of direct sunlight, being the best); and the second is often
useful when the source of illumination is a candle or a lamp. By varying
the angle of the mirror the light is thrown through the object more or
less obliquely, and its quantity should never be sufficient to pain the
eye. Few objects are seen to the best advantage with a _large_ pencil of
perfectly direct light, and the beginner should practise till the amount
of inclination is obtained which produces the best effect.
It is advisable that the hole in the stage of the microscope should be
large--at least an inch and a half each way--so that the entrance of
oblique rays is not obstructed, and it is desirable that the mirror, in
addition to sliding up and down, should have an arm by which it can be
thrown completely out of the perpendicular plane of the body of the
instrument. This enables such oblique rays to be employed as to give a
dark field, all the light which reaches the eye being _refracted_ by the
object through which it is sent. The opticians sell special pieces of
apparatus for this purpose, but though they are very useful, they do not
render it less desirable to have the mirror mounted as described.
Most microscopes are furnished with a revolving diaphragm, with three
holes, of different sizes, to diminish the quantity of light that is
admitted to the object. This instrument is of some use, and offers a
ready means of obtaining a very soft agreeable light for transparent
objects, viewed with low powers. For this purpose cut a circular disk of
India or tissue paper, rather larger than the biggest aperture; scrape a
few little pieces of spermaceti, and place them upon it, then put the
whole on a piece of writing-paper, and hold it a few inches above the
flame of a candle, moving it gently. If this is dexterously done, the
spermaceti will be melted without singeing the paper, and when it is
cold the disk will be found transparent. Place it over the hole in the
diaphragm, send the light through it, and the result will be a very soft
agreeable effect, well suited for many purposes, such as viewing
sections of wood, insects mounted whole, after being rendered
transparent, many small water creatures, etc. Another mode of
accomplishing this purpose is to place a similarly prepared disk of
paper on the flat side of a bull's-eye lens, and transmit the light of a
lamp through it. This plan may be used with higher powers, and the white
opaque light it gives may be directed at any angle by means of the
mirror beneath the stage.
An ordinary lamp may be made to answer for microscopic use, but one of
the small paraffine lamps now sold everywhere for eighteen-pence is
singularly convenient. It is high enough for many purposes, and can
easily be raised by one or more blocks. A paraffine lamp on a sliding
stand is still more handy, and all the better for a hole with a glass
stopper, through which the fluid can be poured.
Many people fancy that the eyes are injured by continual use of the
microscope, but this is far from being the case if reasonable
precautions are taken. The instrument should be inclined at a proper
angle, all excess of light avoided, and the object brought into focus
before it is steadily looked at. Most people solemnly shut one eye
before commencing a microscopic examination; this is a practical and
physiological mistake. Nature meant both eyes to be open, and usually
resents a prolonged violation of her intentions in this matter. It
requires but a little practice to keep both eyes open, and only pay
attention to what is seen by that devoted to the microscope. The
acquisition of this habit is facilitated, and other advantages gained,
by a screen to keep out extraneous light. For this purpose take a piece
of thin cardboard about nine inches square, and cut a round hole in it,
just big enough to admit the tube of the microscope, about two inches
from the bottom, and equidistant from the two sides. Next cut off the
two upper corners of the cardboard, and give them a pleasant-looking
curve. Then cover the cardboard with black velvet, the commonest, which
is not glossy, answers best, and your screen is made. Put the hole over
the tube of the microscope, and let the screen rest on the little ledge
or rim which forms an ornamental finish to most instruments. A piece of
cork may be gummed at the back of the screen, so as to tilt it a little,
and diminish its chance of coming into contact with that important organ
the nose. This little contrivance adds to the clearness and brilliancy
of objects, and is a great accommodation to the eyes.
One more oculistic memorandum, and we have done with this chapter. Do
not stare at portions of objects that are out of focus, and consequently
indistinct, as this injures the eyes more than anything. Remember the
proverb, "None so deaf as those that won't hear," which naturally
suggests for a companion, "None so blind as those that won't see." It is
often impossible to get every object in the field in focus at one
time;--look only at that which is in focus, and be blind to all the
rest. This is a habit easily acquired, and is one for which our
_natural_ microscopes are exceedingly grateful; and every judicious
observer desires to keep on the best terms with his eyes.
CHAPTER II.
JANUARY.
Visit to the ponds--Confervæ--Spirogyra
quinina--Vorticella--Common Rotifer--Three divisions of
Infusoria--Phytozoa--Protozoa--Rotifera--Tardigrada--Meaning of
these terms--Euglenæ--Distinction between animals and
vegetables--Description of Vorticellæ--Dark ground
illumination--Modes of producing it--The Nucleus of the
Vorticellæ--Methods of reproduction--Ciliated Protozoa--Wheel
bearers or Rotifers--Their structure--The common Rotifer--The
young Rotifer seen inside the old one--An internal
nursery--"Differentiation" and "Specialisation"--Bisexuality of
Rotifers--Their zoological position--Diversities in their
appearance--Structure of their Gizzard--Description of Rotifers.
The winter months are on the whole less favorable to the collection of
microscopic objects from ponds and streams than the warmer portions of
the year; but the difference is rather in abundance than in variety, and
with a very moderate amount of trouble, representatives of the principal
classes can always be obtained.
On a clear January morning, when the air was keen, but no ice had yet
skinned over the surface of the water, a visit to some small ponds in an
open field not far from Kentish Town provided entertainment for several
days. The ponds were selected from their open airy situation, the
general clearness of their water, and the abundance of vegetation with
which they were adorned. Near the margin confervæ abounded, their
tangled masses of hair-like filaments often matted together, almost with
the closeness of a felted texture. At intervals, minute bubbles of air,
with occasionally a few of greater size, indicated that the complex
processes of vegetable life were actively going on, that the tiny plants
were decomposing carbonic acid, dexterously combining the carbon--which
we are most familiar with in the black opaque form of charcoal--to form
the substance of their delicate translucent tissues, and sending forth
the oxygen as their contribution to the purification of the adjacent
water, and the renovation of our atmospheric air. This was a good sign,
for healthy vegetation is favorable to many of the most interesting
forms of infusorial life. Accordingly the end of a walking-stick was
inserted among the green threads, and a skein of them drawn up, dank,
dripping, and clinging together in a pasty-looking mass. To hold up a
morsel of this mass, and tell some one not in the secrets of pond-lore
that its dripping threads were objects of beauty, surpassing human
productions, in brilliant colour and elegant form, would provoke
laughter, and suggest the notion that you were poking fun at them, when
you poked out your stick with the slimy treasure at its end. But let us
put the green stuff into a bottle, with some water from its native
haunt, cork it up tight, and carry it away for quiet examination under
the microscope at home.
Here we are with the apparatus ready. We have transferred a few threads
of the conferva from the bottle to the _live box_, spreading out the
fine fibres with a needle, and adding a drop of water. The cover is then
gently pressed down, and the whole placed on the stage of the
microscope, to be examined with a power of about sixty. A light is
thrown somewhat obliquely by the mirror through the object, the focus
adjusted, and a beautiful sight rewards the pains. Our mass of conferva
turns out to contain one of the most elegant species. Fine hair-like
tubes of an organic material, as transparent as glass, are divided by
partitions of the same substance into cylindrical cells, through which a
slender ribbon of emerald green, spangled at intervals with small round
expansions, is spirally wound. We shall call it the Spiral Conferva, its
scientific name being _Spirogyra quinina_. Some other species, though
less elegantly adorned, make a pleasing variety in the microscopic
scene; and appended to some of the threads is a group of small crystal
bells, which jerk up and down upon spirally twisted stalks. These are
the "Bell Flower Animalcules" of old observers, the _Vorticellæ_, or
Little Vortex-makers of the present day. Other small creatures flit
about with lively motions, and among them we observe a number of green
spindles that continually change their shape, while an odd-looking thing
crawls about, after the manner of certain caterpillars, by bringing his
head and tail together, shoving himself on a step, and then repeating
the process, and making another move. He has a kind of snout, behind
which are two little red eyes, and something like a pig-tail sticks out
behind. This is the Common Wheel-bearer, _Rotifer vulgaris_, a
favourite object with microscopists, old and young, and capable, as we
shall see, of doing something more interesting than taking the crawl we
have described.
A higher power, say one or two hundred, may be conveniently applied to
bring out the details of the inhabitants of our live box more
completely; but if the glasses are good, a linear magnification of sixty
will show a great deal, with the advantage of a large field, and less
trouble in following the moving objects of our search.
Having commenced our microscopic proceedings by obtaining some Euglenæ,
Vorticellæ, and a Rotifer, we are in a position to consider the chief
characteristics of three great divisions of infusoria, which will often
engage our attention.
It is well known that animalcules and other small forms of being may be
found in _infusions_ of hay or other vegetable matter, and hence all
such and similar objects were called _Infusoria_ by early observers.
Many groups have been separated from the general mass comprehended under
this term, and it is now used in various senses. The authors of the
'Micrographic Dictionary' employ it to designate "a class of microscopic
_animals_ not furnished with either vessels or nerves, but exhibiting
internal spherical cavities, motion effected by means of cilia, or
variable processes formed of the substance of the body, true legs being
absent." The objection to this definition is, that it to some extent
represents theories which may not be true. That nerves are absent _all
through the class_ is an assumption founded merely upon the negative
evidence of their not having been discovered, and the complete absence
of "vessels" cannot be affirmed.
In the last edition of 'Pritchard's Infusoria,' to which some of our
ablest naturalists have contributed, after separating two groups, the
Desmids, and the Diatoms, as belonging to the vegetable world, the
remainder of the original family of infusoria are classified as
_Phytozoa_, _Protozoa_, _Rotifera_, and _Tardigrada_. We shall explain
these hard names immediately, first remarking that the Desmids and the
Diatoms, concerning whom we do not intend to speak in these pages, are
the names of two groups, one distinctly vegetable, while the other,
although now generally considered so, were formerly held by many
authorities to be in reality animal. The Desmids occur very commonly in
fresh water. We have some among our Confervæ. They are most brilliant
green, and often take forms of a more angular and crystalline character
than are exhibited by higher plants. The Diatoms are still more common,
and we see before us in our water-drop some of their simplest
representatives in the form of minute boats made of silica (flint) and
moved by means still in dispute.
Leaving out the Desmids and Diatoms, we have said that in Pritchard's
arrangement the views of those writers are adopted who divide the rest
of the infusoria into four groups, distinguished with foreign
long-tailed names, which we will translate and expound. First come the
_Phytozoa_, under which we recognise our old acquaintance _zoophyte_
turned upside down. _Zoophytes_ mean animal-plants, _Phytozoa_ mean
plant-animals. We shall have by-and-bye to speak of some of the members
of this artificial and unsatisfactory group, and postpone to that time a
learned disquisition on the difference between animals and plants, a
difference observable enough if we compare a hippopotamus with a
cabbage, but which "grows small by degrees, and beautifully less," as we
contemplate lower forms.
After the _Phytozoa_ come the _Protozoa_, or first forms in which
animality is distinctly recognised. Under this term are assembled
creatures of very various organization, from the extreme simplicity of
the _Proteus_ or _Amoeba_, a little lump of jelly, that moves by
thrusting out portions of its body, so as to make a sort of extempore
legs, and in which no organs can be discerned,[2] up to others that are
highly developed, like our _Vorticellæ_. This group is evidently
provisional, and jumbles together objects that may be widely separated
when their true structure and real affinities are discerned.
[2] In some kinds and in some stages of growth this is not strictly
true.
Following the _Protozoa_, come the _Rotifera_, or Wheel-bearers, of
which we have obtained an example from our pond, and whose
characteristics we shall endeavour to delineate when our specimen is
under view; and last in the list we have the _Tardigrada_,
"Slow-steppers," or Water Bears, queer little creatures, something like
new-born puppies, with a double allowance of imperfect feet. These,
though somewhat connected with the rotifers, are considered to belong to
a low division of the arachnida (spiders, &c.).
[Illustration: --_a_, motile; and _b_, resting condition of Euglenæ.]
Feeling that we must be merciful with the long-tailed words and
explanations of classification, we reserve further matter of this kind
for the opportunities that must arise, and direct our attention to
living forms by watching the _Euglenæ_ which our water-drop contains. We
have before us a number of elegant spindle-shaped bodies, somewhat
thicker in front than behind, and in what may be called the head there
glitters a brilliant red speck, commonly called an _eye-spot_, although,
like the eyes of potatoes, it cannot see. Round this eye-spot the
tissues are clear, like glass; but the body of the creature is of a rich
vegetable green, which shines and glistens as it catches the light. Some
swim rapidly with a rollicking motion, while others twist themselves
into all manner of shapes. Now the once delicate spindle is oddly
contorted, now it swells out in the middle, like a top, and now it rolls
itself into a ball. The drawings will afford some idea of these protean
changes, but they must be seen before their harlequin character can be
thoroughly appreciated. Some of the specimens exhibit delicate lines
running lengthwise, and taking a spiral twist as the creature moves
about; but in none can any mouth be discerned, and their antics,
although energetic and comical, afford no certain indications of either
purpose or will. What are they? animals or vegetables? or something
betwixt and between?
The first impression of any casual observer would be to declare in
favour of their animality; but before this can be settled, comes the
question, what is an animal, and how does it differ from a vegetable?
and upon this the learned do by no means agree. One writer considers the
presence of _starch_ in any object a proof that it belongs to the
dominions of Flora, while another would decide the issue by ascertaining
whether it evolves oxygen and absorbs carbon, as most plants do, or
whether it evolves carbon and absorbs oxygen, as _decided_ animals do.
Dr. Carpenter asserts that the distinction between _Protophyta_ and
_Protozoa_ (first or simplest plants and animals), "lies in the nature
of their food, and the method of its introduction, for whilst the
_Protophyte_ obtains the materials of its nutrition from the air and
moisture that surround it, and possesses the power of detaching oxygen,
hydrogen, carbon, and nitrogen from their previous binary combinations,
and of uniting them into ternary and quaternary organic compounds
(chlorophyll, starch, albumen, &c.), the simplest _Protozoa_, in common
with the highest members of the animal kingdom, seems utterly destitute
of any such power, makes, so to speak, a stomach for itself in the
substance of its body, into which it injects the solid particles that
constitute its food, and within which it subjects them to a regular
process of digestion."
Unfortunately it is very difficult to apply this simple theory to the
dubious objects which lie on the border-land of the animal world, and no
other theory that has been propounded appears to meet all cases. Some
naturalists do not expect to find a broad line of demarkation between
the two great divisions of living things, but others characterise such
an idea as "unphilosophical," in spite of which, however, we incline
towards it.
Mr. Gosse, whose opinion is entitled to great respect, calls the
_Euglenæ_ "animals" in his 'Evenings with the Microscope;' but from the
aggregate of recorded observations it seems that they evolve oxygen, are
coloured with the colouring matter of plants, reproduce their species in
a manner analogous to plants, and have in some cases been clearly traced
to the vegetable world. It is, however, possible that some _Euglenæ_
forms may be animal and others vegetable, and while their place at
nature's table is being decided, they must be content to be called
_Phytozoa_, which, as we have before explained, is merely _Zoophyte_
turned upside down.
Some authorities have thought their animality proved by the high degree
of contractility which their tissues evince. This, however, cannot go
for much, as all physiologists admit contractility to belong to the
vegetable tissues of the sensitive plant, "Venus' Fly-trap," &c., and a
little more or less cannot mark the boundary between two orders of
being.
We shall have occasion again to notice the _Protophytes_, and now pass
to the _Protozoa_, of which we have a good illustration in the
_Vorticella_ already spoken of. In the group before us a number of
elegant bells or vases stand at the end of long stalks, as shown at the
top of the frontispiece, while round the tops of the bells, the
vibrations of a wreath or cilia produce little vortices or whirlpools,
and hence comes the family name. This current brings particles of all
sorts to the mouth near the rim of the bells, and the creature seems not
entirely destitute of power to choose or reject the morsels according to
its taste. Every now and then the stalk of some specimen is suddenly
twisted into a spiral, and contracted, so as to bring the bell almost to
the ground. Then the stem gracefully elongates again, and the cilia
repeat their lively game.
The general effect can be seen very well by a power of about sixty
linear, but one of them from one to two hundred is necessary to bring
out the details, and a practised observer will use still more
magnification with good effect. They should be examined by a moderately
oblique light, or most of the cilia are apt to be rendered invisible,
and also by _dark ground_ illumination. This may be accomplished in a
well-made microscope by turning the mirror quite out of the plane of the
axis of the instrument, that is to say, on one side of the space the
body would occupy if it were prolonged. By this means, and by placing
the lamp at an angle with the mirror, that must be learnt by experiment,
all the light that reaches the eye has first passed through the object,
and is refracted by it out of the line it was taking, which would have
carried it entirely away. Or the object may be illuminated by an
apparatus called a _spotted lens_, which is a small bull's-eye placed
under the stage, and having all the centre of its face covered with a
plaster of black silk. In this method the central or direct rays from
the mirror are obstructed, but those which strike the edge of the
bull's-eye are bent towards the object, which they penetrate and
illuminate if it is sufficiently transparent and refractive. Another
mode of dark ground illumination is by employing an elegant instrument
called a _parabolic illuminator_, which need not be described.
[Illustration: Vorticella, with posterior circlet of cilia in process of
separation, 300 linear.--_Stein._]
[Illustration: Vorticella in process of self-division. A new frontal
wreath in formation in each of the semi-lunar spaces.]
Different specimens and species of _Vorticellæ_ vary in the length of
their bells from one three or four thousandth to one hundred and
twentieth of an inch, and when they are tolerably large, the dark ground
illumination produces a beautiful effect. The bells shine with a pearly
iridescent lustre, and their cilia flash with brilliant prismatic
colours.
[Illustration: Vorticella microstoma, showing alimentary tube, ciliated
mouth, and formation of a gemma at the base, 300 linear.--_Stein._]
[Illustration: Vorticella microstoma, the encysted animal protruding
through a supposed rupture of the tunic.]
The _Vorticellina_ belong to the upper division of the _Protozoa_--the
_ciliata_, or ciliated animalcules, and they have a mouth, an
oesophagus, and an orifice for the exit of their food.
Many observers used to ascribe to those creatures a complete intestinal
canal, but such an apparatus is now believed not to exist in any of the
Infusoria. Food particles, after leaving the oesophagus, are thrust
forward into the sarcode, or soft flesh, and any cavity thus formed acts
as a stomach.
The bells or cups are not, as might be fancied from a casual inspection,
open like wineglasses at the top, but furnished with a retractile disk
or cover, on which the cilia are arranged. Their stalks are not simple
stems, but are hollow tubes, which in the genus Vorticella are furnished
with a muscular band, by whose agency the movements are principally
made.
Some of the Vorticellids will be observed to leave their stalks, having
developed cilia round their base, and may be seen to swim about in the
enjoyment of individual life. They are also capable of becoming
_encysted_, that is, of secreting a gelatinous cover.
[Illustration: Encysted Vorticella, showing the obliteration of special
organs by the advancement of the process.--_Pritchard._]
These changes are exhibited in the annexed cuts, which are copied from
known authorities. By careful observation of the bodies of Vorticellids,
a contractile vesicle may be observed, which appears to cause a movement
of fluids, that is probably connected either with respiration or
secretion.
Another piece of apparatus in this family, but not confined to it, is
the so-called _nucleus_, which in this case is of a horseshoe shape and
granular texture, and greater solidity than the surrounding parts. The
functions of this organ formed the subject of various conjectures, but
it is now generally held to be an ovary.
[Illustration: Vorticella microstoma, in process of encystment, 300
linear; in the last the inclosing tunic is plainly developed.--_Stein._]
In common with many of the lower animals, the Vorticellids have three
ways of multiplying their race. One by _fission_, or division of their
bodies: another by _buds_, somewhat analogous to those of plants; and
another by reproductive germs. These processes will come again under our
notice, and we shall leave the Vorticellids for the present by observing
that if they are fed with a very small quantity of indigo or carmine,
the vacuoles or spaces, into which their nutriment passes, will be
clearly observed. Ehrenberg thought in these and similar creatures that
every vacuole was a distinct stomach, and that all the stomachs were
connected by an intestinal canal; hence his name _Polygastrica_, or
many stomached. In these views he has not been followed by later
observers, and it is probable he was misled, partly by pushing the
process of reasoning from the analogies of higher animals much too far,
and partly by the imperfection of the glasses he employed.
[Illustration: Rotifer vulgaris.--A, mouth, or gizzard; B, contractile
vesicle.--_Micrographic Dictionary._ N.B.--When the cilia and tail part
are retracted, and the body shortened, the creature assumes an obtuse
oval form.]
Having thus briefly considered the Vorticellids we must turn to the
wheel-bearer, who belongs to a higher race than even the ciliated
_Protozoa_. We left her crawling about with her snout or proboscis
protruded, but now she has moored herself by her tail-foot, pulled in
her nose, and put out two groups of cilia, which look like revolving
wheels, and a little below them is seen a gizzard in a state of active
work. After a little while she swims away with her wheels going, and her
tail, forked at the end, is found to be telescopic, or capable of being
pulled in and out. As the cilia play, the neighbouring water is
agitated, and the multitudes of small objects are brought by the
whirlpools within her ravenous maw. But the strangest thing of all is
that inside her body is seen a young one; in this case a large and fine
infant, which, like "a chip of the old block," imitates the parental
motions, thrusts forth its cilia and works its gizzard.[3] In other
genera the eggs are hatched externally, but this one is ovoviparous, and
carries its nursery inside.
[3] This was met with in the summer, but is described here to avoid
repetition. I do not know whether the eggs are hatched in very cold
weather.
A very slight investigation is sufficient to show that in the
wheel-bearer we have made a great advance towards a higher organization
than we discovered in the preceding creatures. We witness what the
learned call a "differentiation" of parts and tissues, and a
"specialization" of organs. The head is plainly distinguishable from the
body, the skin or integument is distinctly different from the internal
tissues, behind the eyes we can detect a nervous ganglion or miniature
brain, the gizzard is a complicated piece of vital mechanism, such as we
have not met with before, and in various parts of the transparent inside
we see organs to which particular functions are assigned.
It was at one time thought that Rotifers were hermaphrodite--uniting
both sexes in one body--but that idea is now generally abandoned, for in
many species the males have been discovered, and the fair sex may be
gratified to hear that they are without doubt the "inferior animals."
Their function is simply to assist the female in producing young, and as
this can be quickly accomplished, their lives are short, and they are
not supplied with the gizzard and digestive apparatus, which their
lady-loves possess. Much discussion has taken place as to the rank which
the Rotifers hold in the animal kingdom, some naturalists thinking them
relations of the crabs, and others believing them to belong to the
family of the worms. Professor Huxley, who adopts the latter view, which
has the most friends, groups the lower _Annulosa_ together under the
name of _Annuloida_, in which he includes _Annelides_, or worms of
various kinds, the _Echinodermata_ (or "spine skins," among which are
the star-fish and sea hedgehogs), and some other families. He considers
the Rotifers to be "the permanent forms of Echinoderm larvæ." This does
not mean that they were ever produced by Echinoderms, and had their
development checked, but that they resemble them in organization, and
illustrate a general law, observable in animated beings, namely, that
the lower creatures are like the imperfect stages of higher animals, and
that all things are formed according to general principles, and exhibit
a uniformity of plan.
Mr. Gosse adopts a different view, and while admitting a connection
between the Rotifers and the worms, adduces important reasons for
associating them with the insects.
Leaving zoologists to settle their position, we may remark that the
Rotifers form a very numerous family, presenting very great diversities
of structure, some of the most interesting of which we shall meet with
in the course of our rambles; but they all possess a gizzard, which,
though differing in complexity, is throughout formed upon the same
principle, and that we must now explain.
We have called the masticatory apparatus of the Rotifers a _gizzard_;
but Mr. Gosse, who has done most to elucidate its structure, contends
that it is a _mouth_; and in some species it is frequently protruded,
and used like the mouth of higher animals. Taking one of the most
typical forms of this organ, and drawing our illustrations from Mr.
Gosse's admirable paper in the "Transactions of the Royal Society," we
may describe it, when completely developed, as consisting of three
lobes, having a more or less rounded form. The eminent naturalist we
have named calls the whole organ the _mastax_, and states that it is
composed of dense muscular fibre. The tube which leads down to it he
designates the "buccal (mouth) funnel," and the tube that issues from
it, and conveys the food to the digestive sac or stomach, he calls the
_oesophagus_, in conformity with the nomenclature applied to creatures
whose mouths are in the usual place. Inside the mouth-gizzard are placed
two organs, which work like hammers, and which Mr. Gosse therefore names
_mallei_. The hammers work against a sort of anvil, which is called
_incus_, the Latin for that implement. Each hammer consists of two
portions articulated by a hinge joint. The lower portion, the
_manubrium_, or handle, gives motion to the upper portion, which from
its shape is named the _uncus_, or hook. The _unci_ are furnished with
finger-like processes of teeth, which vary in number. There are five or
six in the best developed specimens. These hooks or teeth work against
each other, and against the _incus_, or anvil, which consists of
distinct articulated portions, of which the principal are two _rami_, or
branches, jointed so that they can open and close like a pair of shears.
These two rest upon the third portion, which is called the _fulcrum_.
Some faint idea of the working of the toothed hammers may be obtained by
rubbing the knuckles of both hands together, but the motion is more
complicated, and the _rami_ play their part in the trituration of the
food. Mr. Gosse states that when an objectionable morsel has got as far
as this mouth-gizzard, "it is thrown back by a peculiar scoop-like
action of the _unci_, very curious to witness." The foregoing diagram
will help the reader to comprehend this description, but no opportunity
should be lost for viewing this remarkable organ busy at work in the
living animals.
[Illustration: Gizzard of Notomata.]
The respiration of the Rotifers is supposed to be effected by the
passage of water through vessels running round them, and called the
"water vascular system," and in addition to their eyes, which often
disappear in adult specimens, the organ we described as standing out
like a pig-tail, as our acquaintance crawled along, is thought to act as
an _antenna_, or feeler, and brings its possessor in further relation to
the external world. It is also called the _calcar_, or spur, and is
furnished with cilia or bristles at its extremity.
Sometimes the particles swallowed by the Common Rotifer are large enough
for their course to be traced, but there is frequently a great commotion
and grinding of the gizzard, without any appreciable cause, although
doubtless something is taken in, and when the creature is tired, or has
had enough, we see both head and tail retracted, and the body assumes a
globular form. In another chapter, when viewing a Philodine, we shall
see how in the family to which the Common Rotifer belongs, the gizzard
departs from the perfect type.
CHAPTER III.
FEBRUARY.
Visit to Hampstead--Small
ponds--Water-fleas--Water-beetle--Snails--Polyps--Hydra
viridis--The dipping-tube--A glass cell--The Hydra and its
prey--Chydorus sphæricus and Canthocamptus, or friends and their
escapes--Cothurnia--Polyp buds--Catching Polyps--Mode of viewing
them--Structure of Polyps--Sarcode--Polyps stimulated by
light--Are they conscious?--Tentacles and poison
threads--Paramecium--Trachelius--Motions of Animalcules, whether
automatic or directed by a will--Their restless character.
It has been a bitterly cold night, and as the sun shines on a clear keen
morning, and glistens in the hoar-frost which covers the trees, it might
seem an unpropitious time for visiting the ponds, in search of
microscopic prey. We will, however, try our luck, and take a brisk trot
to the top of Hampstead Heath, where the air is still keener, and the
ice more thick. Arriving at the highest point, London appears on one
side enveloped in its usual great coat of smoke, through which St.
Paul's big dome, with a score or two of towers and steeples, can be
dimly made out; while looking towards Harrow-on-the-Hill, or Barnet, we
see the advantage of country air in the sharpness with which distant
objects cut the blue sky. We leave the large ponds for another time,
and hunt out the little hollows among the furze and fern. One looks
promising from the bright green vegetation to be discovered under the
sheet of ice, which is almost firm enough to bear human weight.
Breaking a convenient hole we hook up some of the water-plants, and
place them in a wide-mouthed vial, which we fill with water, and
cursorily examine with a pocket-lens. Some water-fleas briskly skipping
about, and a beautiful little beetle, with an elegant dotted pattern on
his brown back, and a glistening film of air covering his belly, show
that we have not been unsuccessful, although we must wait till we get
home to know the extent of our findings, among which, however, we can
only discern the graceful spiral shell of a small water-snail, the
_Planorbis_.
Arriving at home the bottle was left undisturbed for some hours in a
warm light place, and then on being examined several specimens of that
beautiful polyp, the _Hydra viridis_, were seen attached to the glass,
and spreading their delicate tentacles in search of prey. One of the
polyps is carefully removed by the _dipping-tube_, a small glass tube,
open at both ends. The forefinger is placed upon the top, and when the
other end is brought over the object the finger is raised for an
instant, and as the water rushes in the little hydra comes too, and is
placed in a glass cell, about half an inch wide, and one tenth of an
inch deep. These cells are obtained from the opticians, and cemented
with varnish or marine glue to an ordinary glass slide. After an object
has been placed in one of them, a little water is taken up in the
dipping-tube, and the cell filled until the fluid stands in a convex
heap above its brim. We then select around glass cover, and press it
gently on the walls of our cell. A few drops of superfluous water
escape, and we have the cell quite full, and the cover held tight by
force of the capillary attraction between the water and the glass.
[Illustration: _Hydra viridis_ with developed young one, and bud
beginning to sprout.]
The polyp deposited in one of these water cages is then transferred to
the stage of the microscope, and its proceedings watched. At first it
looks like a shapeless mass of apple-green jelly. Soon, however, the
tail end of the creature is fixed to the glass, the body elongates, and
the tentacles (in this case eight) expand something after the manner of
the leaves of a graceful palm.
By accident two small Water Fleas were imprisoned with the polyp, and
one (a shrimp-like looking creature, carrying behind her a great bag of
eggs) came into contact with the tentacles, and seemed paralysed for a
time. The hydra made no attempt to convey the captive to its mouth, but
held it tight until another Water Flea, a round merry little fellow
(_Chydorus sphæricus_), came to the rescue, and assisted _Canthocamptus_
to escape by tugging at her tail. This friendly action may not have been
prompted by the intelligence which seemed to suggest it, but those who
have kept tame soldier-crabs and prawns in an aquarium, will not be
indisposed to attribute to the crustaceans more brains than they have
usually credit for. It must, however, be confessed that the subsequent
conduct of Mrs. Canthocamptus did not indicate the possession of much
prudence, for she learnt no lesson from experience, but repeatedly swam
against her enemy's tentacles, suffered many captures, and only escaped
being devoured through the indifference, or want of appetite, which the
polyp evinced.
[Illustration: A, _Canthocamptus minutus_; B, _Chydorus sphæricus_; C
and D, Capsules and poison-thread of polyp; E, _Tricodina pediculus_,
side view and under view; F, _Kerona polyporum.--Microg. Dict._]
On the body of the _Canthocamptus_ were some small transparent vases or
bottles, containing living objects, which sprang up and down. These
were members of the _Vorticella_ family, called _Cothurnia_, and will
be hereafter described.
[Illustration: _Hydra viridis_, in various shapes.]
Watching the hydra it was curious to note the changes of form which
these creatures are able to assume. Now the tentacles were short and
thick, and the body squat; now the body was elongated, like the stem of
a palm tree, and the tentacles hung gracefully from the top. From some
of the polyps little round buds were growing, while other buds were
already developed into miniature copies of the parent, and only attached
by a slender stalk. In a few days many of these left the maternal side,
fixed their own little tails to the glass, and commenced housekeeping on
their own account.
Polyps may be obtained at all times of the year by bringing home
duckweed, conferva, and other water-plants from the ponds. Some hauls
may be unsuccessful, but if one pond is not propitious others should be
tried. The plants should be put in a capacious vessel of water, and
placed in the light, where, if polyps be present, they will show
themselves within twenty-four hours, either attached to the sides of the
glass, or hanging from the plants, or suspended head downwards from the
upper film of the water. They are elegant objects, and may be kept
without difficulty for some weeks. After being confined in a small
quantity of water for purposes of examination, they should be carefully
replaced in the larger vessel, and may thus be used again and again
without suffering any injury. A low power--a three or two-inch glass--or
a one-inch, reduced by employing the erector--is the most convenient for
examining the whole creature, but higher powers are necessary to make
out its minute structure. They should be viewed with direct and oblique
light, as transparent and also as opaque objects. In the latter case the
"Lieberkuhn," or polished silver speculum, is convenient, and if the
microscope is not furnished with Lister's dark wells, a small piece of
black paper may be stuck behind the object, by simply wetting it with
the tongue.[4]
[4] The side silver reflector is useful for illuminating such objects.
Although the polyps are remarkable for the simplicity of their
organization, they do not the less exhibit the wonderful nature of
animal life. Their bodies are composed of the substance, called
_sarcode_, in which is imbedded a colouring matter resembling that in
the leaves of plants; every part possesses irritability and
contractility, and they are very sensitive to the stimulus of light. The
outer layer of their bodies is harder than the inner layer. These
layers are severally called _ectoderm_ and _endoderm_. They may be cut
and grafted like trees, and if turned inside out, the new inside digests
and assimilates as well as the old. Whether any form of consciousness
can belong to creatures which have no distinct nervous system is open to
doubt, but it would seem probable from their movements that food and
light afford them something like a pleasurable sensation in a very
humble degree. If we were sufficiently acquainted with the secrets of
molecular combination we might discover that the various functions of
these simple organisms were discharged by different _particles_,
although it is only in higher creatures that muscular particles are
aggregated into muscles, or nerve particles into nerves.
Having examined the general appearance and proceedings of the hydra, let
us cut off a tentacle, or take a small specimen and gently crush it by
pressing down the cover of the live box, and place the object so
prepared under a power of about three hundred linear. If we then
illuminate it with a moderate quantity of oblique light, we shall
discover round the edge of the tentacle a number of small cells or
capsules, from some of which a very slender wire or thread will be
emitted.[5] These are the stinging organs of the polyp, and resemble
those which Mr. Gosse has so ably elucidated in the sea anemones. Some
writers have endeavoured to show that they are not stinging organs at
all, but so large an amount of evidence to the contrary is accumulated
in Mr. Gosse's 'Actinologia Britannica,' that no reasonable doubt
remains. The stinging capsules of the polyp are shown in the annexed
sketch, and also the way in which they are employed, for it fortunately
happened that on exposing one of the hydras to pressure in the live box,
a small worm (_Anguillula_) escaped, which had been pierced with the
minute weapons which are supposed to convey a poison into the wound. The
authors of the 'Micrographic Dictionary' think that the prongs of the
forks, which will be seen to point upwards in the sketch,[6] are
springs, and occupy a reversed position in the capsule cells, and that
their function is to throw out the threads. However this may be, the
polyps, and similarly endowed creatures, have the power of darting out
their poison threads with considerable force, and Mr. Gosse found that
the anemone was able to pierce a thick piece of human skin.
[5] See page 34, C and D.
[6] See page 38.
[Illustration: Anguillula pierced by stinging organs of the _Hydra
viridis_.]
The same excellent observer attributes the emission of the anemone
poison threads, which he considers hollow, to the injection of a fluid.
In their quiescent state, he thinks they are drawn in, like the finger
of a glove, and are forced out as the liquid enters their slender tubes.
Possibly the polyp stinging organs may have the same structure.
Notwithstanding their dangerous weapons, polyps are often infested with
a parasite, the _Trichodina pediculus_, as shown in Fig. E, page 49, and
it must happen that either this visitation is not disagreeable, or that
the Trichodina is not influenced by the poison.
As the plants in the bottles decayed, some of the animalcules died off
and others appeared. In one bottle, containing decaying chara,
_Paramecia_ abounded. The _Paramecia_, of which there are various
species, have always been favourite objects with microscopists. The
Germans call them "slipper animalcules," and they vary in size from
1--96"[7] to 1--1150". They are flat rounded-oblong creatures, with a
distinct integument or skin, "through which numerous vibratile cilia
pass in regular rows."[8] They are furnished with a distinct mouth, and
adult specimens exhibit star-shaped contractile vesicles in great
perfection.
[7] The usual mode of giving dimensions is by fractions thus expressed:
1--96" means one ninety-sixth of an inch.
[8] 'Micrographic Dictionary.'
The swarm of specimens before us belong to one species, _Paramecium
aurelia_, the _Chrysalis animalcule_, and they crowd every portion of
the little water-drop we have taken up, and examined with a power of
about one hundred linear. When they are sufficiently quiet a power of
about four hundred may be used with advantage, and Pritchard recommends
adding a little indigo and carmine to the water, in order to see the
cilia more clearly, or rather to render their action more plain. The
cilia are disposed lengthwise, and Ehrenberg counted in some rows sixty
or seventy of them, making an aggregate of three thousand six hundred
and forty organs of motion in one small animated speck. This number
seems large, but although we have never performed the feat of counting
them, we should have expected it to prove much greater. Unlike most
animalcules they are susceptible of being preserved by drying upon
glass, and we subjoin a figure from Pritchard, of one thus treated, in
which the star-shaped vesicles are clearly seen. These curious organs
communicate with other vessels, and, as we have previously stated, are
probably connected with respiration and excretion.
[Illustration: Paramecium aurelia. A dried specimen showing the
vesicles.--_Pritchard._]
The genus _Paramecium_ is now confined to those creatures which exhibit
rows of longitudinal cilia of uniform length, which are destitute of
hooks, styles, or other organs of motion than the cilia, which have a
lateral mouth, and no eye-spots. One mode of increase is by division,
which may be easily observed; another is through the formation of true
eggs as traced by Balbiani.
Another of the treasures from the pond was a species of _Trachelius_, or
long-necked ciliated animalcule, which kept darting in and out of a
slimy den, attached to the leaf of a water-plant. The body was stout and
fish-shaped, the tail blunt, and the neck furnished with long
conspicuous cilia, which enabled the advancing and retreating movements
to be made with great rapidity. The motions of this creature exhibit
more appearance of purpose and design than is common with animalcules,
but in proportion as these observations are prolonged, the student will
be impressed with the difficulty of assuming that anything like a
reasoning faculty and volition, is proved by movements that bear some
resemblance to those of higher animals, whose cerebral capacities are
beyond a doubt. It is, however, almost impossible to witness motions
which are neither constant nor periodic, without fancying them to be
dictated by some sort of intelligence. We must, nevertheless, be
cautious, lest we allow ourselves to be deceived by reasoning so
seductive, as the vital operations of the lowest organisms may be merely
illustrations of blind obedience to stimuli, in which category we must
reckon food, and until we arrive at forms of being which clearly possess
a ganglionic system, we have no certainty that a real will exists, even
of the simplest kind; and perhaps we must go still higher before we
ought to believe in its presence.
Ehrenberg was much struck with the restless character of many
infusoria--whether he looked at them by day or by night, they were never
still. In fact their motions are like the involuntary actions which take
place in the human frame; and if attached to their bodies we observe
cilia that never sleep, the living membrane of some of our own organs,
the nose, for example, is similarly ciliated, and keeps up a perpetual
though unconscious work.
CHAPTER IV.
MARCH.
Paramecia--Effects of Sunlight--Pterodina patina--Curious
tail--Use of a Compressorium--Internal structure of
Pterodina--Metopidia--Trichodina
pediculus--Cothurnia--Salpina--Its three-sided box--Protrusion
of its gizzard mouth.
The _Paramecia_, noticed in the last chapter, have increased and
multiplied their kind without any fear lest the due adjustment between
population and food should fail to be preserved. A small drop of the
scum from the surface of the water in their bottle is an astounding
sight. They move hither and thither in countless numbers, seldom
jostling, although thick as herrings in a tub, and in many portions of
the field the process of self-fissure, or multiplication by division, is
going on without any symptoms of discomfort on the part of the parent
creature. This is an interesting sight, but we will not linger over it,
for the sun is shining, and there is enough warmth in the air to make it
probable that the ponds will be more prolific than in the cold winter
months. Sunshine is a great thing for the microscopic hunter; it brings
swarms of creatures to the surface, and the Rotifers are especially fond
of its genial beams. Even if we imitate it by a bright lamp, we shall
attract crowds of live dancing specks to the illuminated side of a
bottle, and may thus easily effect their capture by the dipping-tube.
[Illustration: Pterodina patina.]
This year the March sunshine was not lost, for on the third of that
month I obtained a bottleful of conferva from a pond about a mile from
my house, and lying at the foot of the Highgate hills. Water-fleas were
immediately discovered in abundance, together with some minute worms,
and a ferocious-looking larva covered with scales; but what attracted
most attention was a Rotifer, like a transparent animated soup-plate,
from near the middle of which depended a tail, which swayed from side to
side, as the creature swam along. The head exhibited two little red
eyes; two tufts of cilia rowed the living disk through the water, and
the gizzard worked with a rapid snapping motion, that left no doubt the
ciliary whirlpools had brought home no slender stores of invisible food.
Sometimes the end of the tail acted as a sucker, and fixed the animal
tightly to the glass, when the wheels were protruded, and the body
swayed to and fro. Then the sucker action ceased, and as the creature
swam away, a tuft of cilia was thrust out from the extremity of the
tail. A power of one hundred linear was sufficient to enable the general
nature of this beautiful object to be observed, but to bring out the
details, much greater amplification was required, and this would be
useless if the little fidget could not be kept still.
[Illustration: Pterodina patina--gizzard.]
The size of the creature, whose name we may as well mention was
_Pterodina patina_, rendered this practicable, but required some care.
The longest diameter of the body, which was not quite round, was about
1--120", so that it was visible to the naked eye, and as a good many
were swimming together, one could be captured without much difficulty,
and transferred with a very small drop of water to the live-box. Then
the cover had to be put on so as to squeeze the animal just enough to
keep it still without doing it any damage, or completely stopping its
motions. This was a troublesome task, and often a little overpressure
prevented its success.
Some observers always use in these cases an instrument called a
_compressorium_, by which the amount of pressure is regulated by a lever
or a fine screw; but whether the student possess one or not, he should
learn to accomplish the same result by dexterously manipulating a
well-made live-box. We will suppose the _Pterodina_ successfully caged,
and a power of about one hundred and fifty linear brought to bear upon
her, for our specimen is of the "female persuasion." This will suffice
to demonstrate the disposition and relation of the several parts, after
which one of from four hundred to five hundred linear may be used with
great advantage, though in this case the illumination must be carefully
adjusted, and its intensity and obliquity frequently changed, until the
best effect is obtained.
We find, on thus viewing the Pterodina, that it is a complex, highly
organized creature, having its body protected by a _carapace_, like the
shell of a tortoise, but as flexible as a sheet of white gelatine paper,
which it resembles in appearance. Round the margin of this carapace are
a number of little bosses or dots, which vary in different individuals.
The cilia are not disposed, as at first appeared, in two separate and
distinct disks, but are continuous, as in the annexed sketch. Down each
side are two long muscular bands, distinctly _striated_, and when they
contract, the ciliary apparatus is drawn in. As this contraction takes
place, two apparently elastic bands, to which the ciliary lobes are
attached, are bent downwards, till they look like the C springs behind a
gentleman's carriage; and they regain their former position of slight
curvature, when the cilia are again thrust out.
[Illustration: Pterodina patina--tail-foot.]
The gizzard is three-lobed, and curiously grasped by forked expansions
of the handles of the hammers. The tail, or tail-foot, can be withdrawn
or thrust out at the will of the creature; and when in a good position
for observation, a slight additional pressure will keep it so for
examination. Delicate muscular longitudinal bands, forked towards the
end of their course, supply the means of performing some of its motions,
and one, or perhaps two, spiral threads extend through the upper half of
its length, and either act as muscles, or as elastic springs for its
extension. The intestines and other viscera are clearly exhibited, and a
strong ciliary action conducts the food to the gizzard-mouth.
To return to the tail. One spiral fibre is easily discovered; but I
have often, and at an interval of months, seen the appearance of two,
and am in some doubt whether this was a deception, arising from the
compression employed, or was a genuine indication.
[Illustration: A. Metopidia acuminata, as drawn by Mr. Gosse. B.
Specimen as seen and described in text. _c._ Mouth or gizzard.]
Where this Rotifer occurs I have usually found it plentiful, but
unfortunately could obtain no constant supplies after I had determined
to make a special study of the remarkable tail, which is much more
complicated than I have described. The _Pterodina_ lived for some time
in captivity, and for a week or two I could obtain them from my glass
tank. They were likewise to be found for some weeks in the same part of
the pond, but not all over it, until one day not a single specimen could
be discovered, notwithstanding a persevering search nor was I
afterwards able to get any from that pond during the remainder of the
year.
[Illustration: Trichodina pediculus.]
Several other Rotifers, with and without carapaces, were among the same
mass of confervæ, among them a _Metopidia_, with a firm shell, a forked
jointed tail, and a projection in front which worked like a pickaxe
among the decaying weed. There were likewise specimens of the
long-necked animalcules (Trachelii), groups of Vorticella, some
specimens of Volvox, and a small _Trichodina pediculus_, which, when
magnified two hundred and sixty linear, was about the size of a sixpence
and equally round. The edge was beautifully fringed with a circle of
cilia; in an inner circle was a row of locomotive organs, and the centre
exhibited vacuoles constantly opening and shutting. This creature, as
before explained, is often found as a parasite upon the polyps. On one
occasion a glimpse was caught of a Rotifer similar in shape to the
common wheel animalcule, but with a yellow inside. Possibly it was the
object so beautifully delineated by Mr. Gosse, in his "Tenby," and
described as the "Yellow Philodine," but this must remain in doubt, as
it managed to escape before it could be secured.
[Illustration: A. Cothurnia imberbis--('Micrograph. Dict.') B and C. The
specimens described in text. The figures give the _linear_
magnification.]
By the 18th of the month the Vorticellids were much more plentiful, and
their changes easily watched; many left their stalks while under the
microscope, after which some rushed about like animated and demented
hats, others twirled round like tee-to-tums, while others took a rest
before commencing their wild career. But the common Vorticellæ were not
the only or the most interesting representations of their charming
order, for upon some threads of conferva were descried several elegant
crystal vases standing upon short foot-stalks, and containing little
creatures that jumped up and down like "Jack in the box." These were so
minute, that a power of four hundred and thirty linear was
advantageously brought to bear upon them. When elongated their bodies
were somewhat pear-shaped, but more slender, and variegated with
vacuoles and particles of food. The mouths resembled those of
Vorticellæ, and put forth circles of vibrating cilia. They were easily
alarmed, when the cilia were retracted, and down they sank to the bottom
of their vases, quickly to rise again. In one bottle there were two
living in friendly juxtaposition. This was not a case of matrimonial
felicity, nor of Siamese twins, but of _fission_, or reproduction by
division. The original inhabitant of the tube finding himself too fat,
or impelled by causes we do not understand, quietly divided himself in
two, and as the house was big enough, no enlargement was required. How
many stout puffy gentlemen must envy this process; how convenient to
have two thin lively specimens of humanity made out of one too obese for
locomotion. Man is, however, sometimes the victim of his superior
organization, and no process of "fission" can make the lusty lean.[9]
[9] Balbiani in his 'Recherches sur les Phénomènes Sexuels des
Infusoires,' speaks of the Vorticellids as the only Infusoria dividing
longitudinally. In other species such appearances arise from
conjunction.
The bottles in which these creatures live, in happy ignorance that they
are called by so crackjaw a name as _Cothurnia imberbis_, were described
as _Carapaces_ by Ehrenberg, but they bear no resemblance to the shell
of a turtle or crab. They are thrown off by the animals who preserve no
other connection with them than the attachment at the bottom.
The Micrographic Dictionary describes the family Ophrydina as
corresponding to Vorticellina with a carapace. Stein places them with
Vorticellids, &c., amongst his Peritricha, which are characterised by a
spiral wreath of cilia round the mouth.
Towards the end of the month a great number of black pear-shaped bodies
(Stentor niger), visible to the naked eye, were conspicuous in some
water from the Kentish Town ponds. Upon examination they were found to
be filled with granules that were red by reflected, and purple by
transmitted light. Each one had a spiral wreath of cilia, with a mouth
situated like those of the stentors, hereafter to be described, but none
of them became stationary, and in a few days they all disappeared. Stein
divides Ehrenberg's Stentor igneus from S. niger; the creature described
seems to have agreed with Stein's _igneus_, which he describes as having
blood-red lilac, cinnabar, or brown-red pigment particles, and as much
smaller than his S. niger. In the same water were specimens of that
singular Rotifer, the _Salpina_, about 1--150" long, and furnished with
a _lorica_, or carapace, resembling a three-sided glass box, closed
below, and slightly open along the back. At the top of this box were
four, and at the bottom three, points or horns, and the creature had one
eye and a forked tail. Keeping him company was another little Rotifer,
named after its appearance, _Monocerca rattus_, the 'One-tailed Rat.'
This little animal had green matter in its stomach, which was in
constant commotion. I ought to have observed that the Salpina repeatedly
thrust out its gizzard, and used it as an external mouth. In the annexed
sketch the Salpina is seen in a position that displays the dorsal
opening of the carapace. Its three-cornered shape is only shown by a
side view.
[Illustration: Salpina redunca.]
Here we close a brief account of what March winds brought in their
train. The next chapter will show the good fortune that attended April
showers.
CHAPTER V.
APRIL.
The beautiful Floscule--Mode of seeking for Tubicolor
Rotifers--Mode of illuminating the Floscule--Difficulty of
seeing the transparent tube--Protrusion of long
hairs--Lobes--Gizzard--Hairy lobes of Floscule not rotatory
organs--Glass troughs--Their construction and use--Movement of
globules in lobes of Floscule--Chætonotus larus--Its mode of
swimming--Coleps hirtus--Devourer of dead Entomostraca--Dead
Rotifer and Vibriones--Theories of fermentation and
putrefaction--Euplotes and Stylonichia--Fecundity of
Stylonichia.
Few living creatures deserve so well the appellation of "beautiful" as
the _Floscularia ornata_, or Beautiful Floscule, although to contemplate
a motionless and uncoloured portrait, one would imagine that it
exhibited no graces of either colour or form. Mr. Gosse has, however,
done it justice, and the drawing in his "Tenby" is executed with that
rare combination of scientific accuracy and artistic skill, for which
the productions of his pencil are renowned.
[Illustration: The Beautiful Floscule. A.--Partially protruded.
B.--Freely protruded, with three eggs. C.--Appearance of young.
D.--Floscule seventeen hours old. D'.--Jaws of Floscule, as figured by
Mr. Gosse.]
Probably the sketches in several works of authority representing the
long cilia as short bristles, are merely copies from old drawings, from
objects imperfectly seen under indifferent microscopes, and before
the refinements of illumination were understood. Be this as it may, any
reader will be fortunate if on an April, or any other morning, he or she
effects the capture of one of these exquisite objects, although the
first impression may not equal previous expectations, as the delicacy of
the organism is not disclosed by a mode of using the light which answers
well enough for the common infusoria.
When the Floscules, or other tubicolar Rotifers are specially sought
for, the best way is to proceed to a pond where slender-leaved
water-plants grow, and to examine a few branches at a time in a phial of
water with a pocket-lens. They are all large enough to be discerned, if
present, in this manner, and as soon as one is found, others may be
expected, either in the same or in adjacent parts of the pond, for they
are gregarious in their habits. With many, however, the first finding of
a Floscule will be an accident, as was the case last April, when a small
piece of myriophyllum was placed in the live-box, and looked over to see
what it might contain. The first glimpse revealed an egg-shaped object,
of a brownish tint, stretching itself upon a stalk, and showing some
symptoms of hairs or cilia at its head. This was enough to indicate the
nature of the creature, and to show the necessity for a careful
management of the light, which being adjusted obliquely, gave quite a
new character to the scene. The dirty brown hue disappeared, and was
replaced by brilliant colours; while the hairs, instead of appearing few
and short, were found to be extremely numerous, very long, and
glistening like delicate threads of spun glass.
Knowing that the Floscules live in transparent gelatinous tubes, such an
object was carefully looked for, but in this instance, as is not
uncommon, it was perfectly free from extraneous matter, and possessed
nearly the same refractive power as the water, so that displaying it to
advantage required some little trouble in the way of careful focusing,
and many experiments as to the best angle at which the mirror should be
turned to direct the light. When all was accomplished, it was seen that
the Floscule had her abode in a clear transparent cylinder, like a thin
confectioner's jar, which she did not touch except at the bottom, to
which her foot was attached. Lying aside her in the bottle were three
large eggs, and the slightest shock given to the table, induced her to
draw back in evident alarm. Immediately afterwards she slowly protruded
a dense bunch of the fine long hairs, which quivered in the light, and
shone with a delicate bluish-green lustre, here and there varied by
opaline tints.
The hairs were thrust out in a mass, somewhat after the mode in which
the old-fashioned telescope hearth-brooms were made to put forth their
bristles. As soon as they were completely everted, together with the
upper portion of the Floscule, six lobes gradually separated, causing
the hairs to fall on all sides in a graceful shower, and when the
process was complete, they remained perfectly motionless, in six hollow
fan-shaped tufts, one being attached to each lobe. Some internal ciliary
action, quite distinct from the hairs, and which has never been
precisely understood, caused gentle currents to flow towards the mouth
in the middle of the lobes, and from the motion of the gizzard,
imperfectly seen through the integument, and from the rapid filling of
the stomach with particles of all hues, it was plain that captivity had
not destroyed the Floscule's appetite, and that the drop of water in the
live-box contained a good supply of food.
Sometimes the particles swallowed were too small to be discerned,
although their aggregate effect was visible; but often a monad or larger
object was ingulfed, but without any ciliary action being visible to
account for the journey they were evidently compelled to perform. The
long hairs took no part whatever in the foraging process, and as they do
not either provide victuals or minister to locomotion, they are clearly
not, as was supposed by early observers, representatives of the
"wheels," which the ordinary Rotifers present. Neither can the
cylindrical jar or bottle be justly deemed to occupy the position of the
lorica, or carapace which we have before described. The general
structure of the creature and the nature of its gizzard distinctly
marked it out as a member of the family we call "Rotifers," but the
absence of anything like "wheels" proves that those organs are not
essential characteristics of this class.
Noticeable currents are not always produced when the mouth of this
Floscule is fully expanded. On one occasion, one having five lobes was
discovered standing at such an angle in a glass trough that the aperture
could be looked down into. The position rendered it impossible to use a
higher power than about two hundred linear, but with this, and the
employment of carmine, nothing like a vortex was seen during a whole
evening, although a less power was sufficient to show the ciliary
whirlpools made by small specimens of _Epistylis_ and _Vaginicola_,
which were in the small vessel. The density of the integument was
unfavorable to viewing the action of the gizzard, but it could be
indistinctly perceived. The contractions and subsequent expansions of
the cup, formed by the upper part of the creature, may be one way in
which its food is drawn in, but there is no doubt it can produce
currents when it thinks proper. Sometimes animalcules in the vicinity of
Floscules whirl about as if under the influence of such currents. Some
may be seen to enter the space between the lobes, swim about inside, and
then get out again, while every now and then one will be sucked in too
far for retreat.
Above the gizzard in the Horned Floscule,[10] I have seen an appearance
as if a membrane or curtain was waving to and fro, while another was
kept in a fixed perpendicular position. Mr. Gosse, speaking of this
genus, observes "that the whole of the upper part of the body is lined
with a sensitive, contractile, partially opaque membrane, which a little
below the disk recedes from the walls of the body, and forms a
diaphragm, with a highly contractile and versatile central orifice. At
some distance lower down another diaphragm occurs, and the ample chamber
thus enclosed forms a kind of _crop_, or receptacle for the captured
prey."
[10] The Horned Floscules (_F. cornuta_) which I have found, and which
bred in a glass jar, were not so large as those described by Mr. Dobie,
as quoted in 'Pritchard's Infusoria.' Mr. Dobie's specimens were 1--40"
when extended; mine about half that size, five-lobed, and with a long
slender proboscis, standing in a wavy line outside one lobe. Mr. Dobie
also describes an _F. campanulata_, with five flattened lobes. The
'Micrographic Dictionary' pronounces these two species "doubtfully
distinct." I have three or four times met with a variety of _F. ornata_,
in which one lobe was much enlarged and flattened, but they had no
proboscis. In what I take for _F. cornuta_, the horn or proboscis has
sometimes been a conspicuous object, and at others so fine and
transparent as to be only visible in certain lights.
"From the ventral side of the ample crop that precedes the stomach,
there springs in _F. ornata_ a perpendicular membrane or veil, partly
extending across the cavity. This is free, except at the vertical edge,
by which it is attached to the side of the chamber, and being ample and
of great delicacy, it continually floats and waves from side to side. At
the bottom of this _veil_, but on the dorsal side, are placed the jaws,
consisting of a pair of curved, unjointed, but free _mallei_, with a
membranous process beneath each."
The Beautiful Floscule could always be made to repeat the process of
retreating into her den, and coming out again to spread her elegant
plumes before our eyes, by giving the table a smart knock, and her
colours and structure were well exhibited by the dark-ground
illumination, which has been explained in a previous page.
An object like this should be watched at intervals for hours and even
days, especially if the eggs are nearly ready to give up their infantile
contents. This was the case with the specimen described, and after a few
hours a young Floscule escaped, looking very much like a clumsy little
grub. After a few awkward wriggles the new-born baby became more quiet,
and on looking at it again at the expiration of seventeen hours, it had
developed into the shape of a miniature plum-pudding, with five or six
tiny lobes expanding their tufts of slender hair. Unfortunately its
further proceedings were not seen, or it would have been interesting to
note the growth of the foot, and the formation of the gelatinous tube,
which is probably thrown off in rings.
To view the details of the structure of a Floscule, it must be placed in
a live-box or compressorium, and if specimens are scarce, they should
not be allowed to remain in the limited quantity of water those
contrivances hold, after the observations are concluded, but should be
carefully removed, and placed in a little vial, such as homoeopathists
use for their medicine. By such means an individual may be kept alive
for many days. It is also interesting to place a little branch of the
plant occupied by Floscules or similar creatures, in a glass trough,
where they may be made quite at home, and their proceedings agreeably
watched by a one-inch or two-thirds power. These troughs,[11] which can
be obtained of the optician, should be of plate glass, about three
inches long, nearly the same height, and about half an inch wide. If
narrower, or much taller, they will not stand, which is a great
inconvenience. The pieces of glass are stuck together with marine glue,
and a very simple contrivance enables the plants or other objects to be
pressed near the front, and thus brought into better view. A strip of
glass, rather narrower than the width of the trough, is dropped into it,
and allowed to fall to the bottom. Then a piece of glass rather shorter
than the trough, and rather higher than its front side, is placed so as
to slope from the front of the bottom towards the back at the top. The
piece of glass first dropped in keeps it in the right position, and the
trough is thus made into a V-shaped vessel, wide at the top and
gradually narrowing. Any object then placed in it will fall till it fits
some part of the V, where it will remain for observation. A small wedge
of cork enables the moveable piece of glass to be thrown forwards, until
it assumes any angle, or is brought parallel to the front of the trough.
[11] The shallow cells with thin sliding covers devised by Mr. Curteis
(of Baker's), are still more convenient when no pressure is required,
and the objects are small. When not under the microscope they can be
kept full of water by immersion in a tumbler.
A power of five or six hundred diameters generally enables a movement of
small globules to be seen at the extremity of the lobes of the Floscule,
and the gizzard may be made plain by dissolving the rest of the creature
in a drop of solution of caustic potash. It also becomes more visible as
the supply of food falls short. Mr. Gosse describes the body as "lined
with a yellowish vascular membrane," and young specimens exhibit two red
eyes, which may or may not be found in adults. When these eyes of
Rotifers are not readily conspicuous, they must be sought for by opaque
illumination, or by the dark-ground method which, especially with the
parabola, is successful in bringing them out.
Naturalists, and possibly the specimens also, do not always agree in
the number of lobes assigned to the "Beautiful Floscule," and although
it is easy enough to count them in _some_ positions, the observer may
have to exercise a good deal of patience before he is certain whether
they are five or six. For a long evening only five could be discerned in
the specimen now described, but the next night six were apparent without
difficulty or doubt. The hairs also will not appear anything like their
true length or number, unless the object-glass is good, and great care
is taken not to obscure them by a blaze of ill-directed light.
[Illustration: Chætonotus larus (swimming).]
After the Floscules had been sufficiently admired and put aside, for
observations to be repeated on future occasions, a Rotifer attracted
attention by his merry-andrew pranks, throwing himself in all directions
by means of two long and extremely mobile toes attached to his
tail-foot. Then came a creature swimming like an otter, thrusting his
head about on all sides, and looking much more intelligent than most of
his compeers of the pond. Looked at vertically, he was somewhat
slipper-shaped, the rounded heel forming his head, then narrowing to a
waist, and expanding towards the other end, which projected in a fork.
All round him were long cilia, which were conspicuous near the head, and
a fine line indicated the passage from his mouth to the stomach, which
seemed full of granular matter. Presently he took to crawling, or rather
running, over a thread of conferva, and then his back was elegantly
arched, and his cilia stood erect like the quills of a porcupine. This
was the _Chætonotus larus_.
[Illustration: Chætonotus larus (crawling).]
In Pritchard's "Infusoria," the views of those writers are followed who
rank this animal amongst the Rotifers, and place it in the family
_Icthidina_. To help out this theory, the cilia upon the ventral surface
are imagined to form a "band-like rotary organ;" but in truth they bear
no resemblance whatever to the so-called wheels of the ordinary
Rotifers, nor is there anything like the gizzard which true Rotifers
present. Ehrenberg treated it as a Rotifer, and Dujardin placed it among
the Infusoria, in a particular class, comprehending symmetrical
organisms. The 'Microscopic Dictionary' remarks that its "structure
requires further investigation,"[12] and while the learned decide all
the intricate questions of its zoological rank, the ordinary observer
will be pleased to watch its singular aspect and lively motions. Its
size, according to the 'Micrographic Dictionary,' varies from 1--710" to
1--220", and while its general proceeding may be watched with an inch or
two-thirds object-glass, and the second eye-piece, a power of five
hundred linear (obtained by a quarter or a fifth) is required to make
out the details of its structure. If placed in a live-box with threads
of conferva, and a little decayed vegetation, it may be observed to
group about among them, and shake them like a dog.
[12] See a valuable paper by Mr. Gosse, "History of the Hairy-backed
Animalcules," 'Intellectual Observer,' vol. v, p. 387, in which the
known species are described and reasons given for following Vogt and
ranging them with the Turbellarian worms.
We have said that water-fleas were among the inhabitants of a bottle
filled at the pond, and as they go the way of all flesh, it is common to
find some odd-looking animalcules ready to devour their mortal remains.
These are creatures shaped like beer-barrels, upon short legs, and which
swim with a tubby rolling gait. Looking at one of these little tubs
lengthwise, a number of lines are seen, as though the edge of each stave
projected a little above the general level, and transverse markings are
also apparent, which may be compared to hoops. This is the _Coleps
hirtus_, which differs from the usual type of Infusoria, by being
symmetrical, that is, divisible into two equal and similar halves. The
dimensions of this species vary from 1--570 to 1--430, and its colour
varies from white to brown. It has been observed to increase by
transverse self-division, and has two orifices, one at each end, for
receiving food and ejecting the remains. It often requires some little
trouble to get a good view of the cilia, which are arranged in
transverse and longitudinal rows. A power of one hundred and fifty
linear is convenient for viewing it in motion, but when quiet under
pressure, one of five or six hundred may be used with advantage.
[Illustration: Coleps hirtus.]
Among the rubbish at the bottom of the bottle, in which the coleps was
found, was a minute dead Rotifer, the flesh of which was fast
disappearing, but upon being examined with a power of nine hundred and
sixty diameters, it was observed to swarm with extremely minute
_vibriones_, the largest only appearing under that immense magnification
like chains of bluish-green globules, not bigger than the heads of
minikin pins, while the smallest were known by a worm-like wriggling,
although their structure could not be defined. These _vibriones_ are
probably members of the vegetable world, and they always appear when
animal matter undergoes putrefaction.
M. Pasteur has brought forward elaborate experiments to show that the
development of the yeast plant is an act correlative to alcoholic
fermentation, and in like manner the growth of _vibriones_ may stand in
correlation to putrefactive decomposition.
[Illustration: A, Euplotes (patella); B, side view of ditto; C,
stylonichia.]
Ehrenberg considered them animals, and fancied he detected in them a
plurality of stomachs; but the vegetable theory is the more probable, at
any rate of the species under our notice, which is often seen, though
not always so minute.
At this time two interesting animalcules were very plentiful--the
_Euplotes patella_, and _Stylonichia_, both remarkable as exhibiting an
advance in organization, which approximates them to the higher animals.
In addition to cilia they possess _styles_, which take the place of the
limbs of more elaborately-constructed creatures, and give a variety to
their means of locomotion. The _Euplotes_ is furnished with an oval
carapace covering the upper surface, which in different individuals, and
probably at different ages, exhibits slightly varied markings round its
margin, which in the specimen drawn above consisted of dots. They can
run, climb, or swim, and exemplify a singular habit which several of the
infusoria possess, that of moving for a little time in one direction,
and then suddenly, and without any apparent cause, reversing it. If the
reader is fond of learned appellations, he can call this _diastrophy_,
but we do not know that he will be any the wiser for it.
The Stylonichia are oval animalcules, surrounded by cilia, and having
moreover a collection of styles, both straight and curved, the latter
called _uncini_, or little hooks. They swim steadily on, and then dart
back, but not so far as they have advanced, and may be seen to keep up
this fidgety motion by the hour together. Pritchard tells us Ehrenberg
found that a single animalcule lived nine days; during the first
twenty-four hours it was developed by transverse self-division into
three animals; these in twenty-four hours formed two each in the same
manner, so that by self-division only (without ova), these animalcules
increased three or four-fold in twenty-four hours, and _may thus produce
a million_ from a single _animalcule in ten days_. Such are the amazing
powers of reproduction conferred upon these humble creatures, powers
which are fully employed when the surrounding circumstances are
favorable, and which, in the aggregate, change the condition of large
masses of matter, and bring within the circle of life millions upon
millions of particles every minute of the day.
CHAPTER VI.
MAY.
Floscularia cornuta--Euchlanis triquetra--Melicerta ringens--its
powers as brickmaker, architect, and mason--Mode of viewing the
Melicerta--Use of glass-cell--Habits of Melicerta--Curious
Attitudes--Leave their tubes at
death--Carchesium--Epistylis--Their elegant tree forms--A
Parasitic Epistylis like the "Old Man of the Sea"--Halteria and
its Leaps--Aspidisca Lynceus.
May, the first of summer months, and of old famous for floral games,
which found their latest patrons in the chimney-sweeps of London, is a
good time for the microscopist among the ponds, for the increase of
warmth and heat favours both animal and vegetable life, and so we found
as we carried home some tops of myriophyllum, and soon discovered a
colony of tubicolor rotifers among the tiny branches. They proved to be
Floscules, generally resembling the _F. ornata_, described in a previous
page, but having a long slender proboscis hanging like a loose ringlet
down one side. The cilia or hairs were not so long as in the Beautiful
Floscules we had before obtained, nor was their manner of opening so
elegant; but they were, nevertheless, objects of great interest, and
were probably specimens of the _Floscularia cornuta_. A swimming rotifer
in a carapace somewhat fiddle-shaped, with one eye in its forehead, and
a two-pronged tail sticking out behind (the _Euchlanis triquetra_), also
served to occupy attention; but a further search among the myriophyllum
revealed more treasures of the tube-dwelling kind. These were specimens
of that highly curious Rotifer, the _Melicerta ringens_, who, not
content with dwelling, like the Floscules, in a gelatinous bottle, is at
once brickmaker, mason, and architect, and fabricates as pretty a tower
as it is easy to conceive. The creature itself stands upon a retractile
foot-stalk, and thrusts out above its battlements a large head, with
four leaf-like expansions surrounded by cilia. Between the lower lobes,
or leaves, the gizzard is seen grinding away, and above it is an organ,
not always displayed, and of which Mr. Gosse was fortunate enough to
discover the use. This eminent naturalist likens it to the circular
ventilator sometimes inserted in windows, and he found it was the
machine for making the yellow ornamental bricks of which the tower is
composed. Pellet by pellet, or brick by brick, does the Melicerta build
her house, which widens gradually from the foundation to the summit, and
every layer is placed with admirable regularity.
In order to obtain the materials for her brickmaking the Melicerta must
have the power of modifying the direction of the ciliary currents, so as
to throw a stream of small particles into the mould, which is a muscular
organ, and capable of secreting a waterproof cement, by which they are
fastened together. The result is, not to produce anything like the tubes
made by the caddis-worms out of grains of sand, but entirely to change
the appearance of the materials employed. All large particles are
rejected, and only those retained which will form a homogeneous pulp
with the viscid secretion; and when the process is complete the head of
the creature is bent down, and the pellet deposited in its appropriate
place. Each pellet appears originally to possess a more or less conical
figure, but when they are squeezed together to make a compact wall they
all tend to a hexagonal form, by which they are able to touch at all
points, and any holes or interstices are avoided.
According to Professor Williamson the young Melicerta commences her
house by secreting "a thin hyaline cylinder," and the first row of
pellets are deposited, not at the base as would be expected, but in a
ring about the middle of the tube. "At first new additions are made to
both extremities of the enlarging ring; but the jerking constrictions of
the animal at length force the caudal end of the cylinder down upon the
leaf, to which it becomes securely cemented by the same viscous
secretion as causes the little spheres to cohere."
Round the margins of the lobes or expansions may be seen delicate
threads towards which others radiate; these are thought by Mr. Gosse to
be portions of a nervous system, and two calcars or feelers serve as
organs of relation. The young Melicertas are likewise furnished with a
pair of eyes, which are probably rudimentary, and disappear as they grow
up.
The Melicerta tubes, being large enough to be visible to the naked eye,
are easily crushed in the live-box, and to avoid this, they are
conveniently viewed in a shallow glass cell, covered up as before
described. By occasionally changing the water one may be kept for days
in the same cell, and will reward the pains by frequently exposing its
flower-like head. Usually the horns or feelers come out first, and then
a lump of flesh. After this, if all seems right, the wheels appear, and
make a fine whirlpool, as may be readily seen by the use of a little
indigo or carmine.
The Melicerta is, however, an awkward object to undertake to show to our
friends, for as they knock at the door she is apt to turn sulky, and
when once in this mood it is impossible to say when her fair form will
reappear. At times the head is wagged about in all directions with
considerable vehemence, playing singular antics, and distorting her
lobes so as to exhibit a Punch and Judy profile. When these creatures
die they leave their tubes, which are often found empty in the ponds
they frequent. The Melicertas are conveniently viewed with a power of
from sixty to one hundred linear, and a colony of them may be kept alive
for some weeks in a glass jar or tank.
Among the remainder of my tiny captives were two beautiful members of
the Vorticella family, _Epistylis_ and _Carchesium_. The reader will
remember that in the Vorticella previously described, the bells stood
upon stalks that were very flexible, and retractile by means of a muscle
running down their length. The _Epistylis_ is, as its name imports, the
dweller on a _pillar_. The stem is stiff, or only slightly flexible, and
has no apparatus by which it can be drawn down. The specimen mentioned
stood like a palm-tree, and the large oval bells drooped elegantly on
all sides, as its portrait will show. At times they nodded with a rapid
jerk.
[Illustration: Epistylis.]
The _Carchesium_ differs from the common _Vorticella_, by branching like
a tree, but the stems are all retractile, although the trunk seldom
exercises the power. A group of these creatures presents a spectacle of
extraordinary beauty--it looks like a tree from fairy-land, in which
every leaf has a sentient life. In general structure the bells of the
_Epistylis_ and the _Carchesium_ resemble the common _Vorticella_, and
like them may be seen with a power of about one hundred linear for
general effect, and with a higher one for the examination of special
points. Pritchard notices three species of _Carchesium_, and eighteen of
_Epistylis_;[13] some of which it is to be hoped will turn out to be
only varieties.
[13] An interesting _Epistylis_, called _Digitalis_, from its bells
resembling fox-glove flowers in shape, occurs as a parasite upon the
_Cyclops quadricornis_, a very common entomostracan in fresh-water
ponds. At this moment I have a beautiful specimen, branching like a
bushy tree, and attached to the tail of a _Cyclops_, who can scarcely
move under his burden, which is like Sinbad's "Old Man of the Sea."
Towards the end of this month rotifers abounded, and polyps were
plentiful. Among the rotifers was one about a two-hundredth of an inch
long, protected by a carapace, and having a tail terminating in a single
style, hence called "Monostyle." There is perhaps no class of creatures
that present so many curious and unexpected forms as the rotifers; and
although we have noticed a good many, there are far more that remain to
be found and described.
The water in which the preceding animals dwelt was enlivened by the
jumps of the _Halteria_, a little globe surrounded by long fine cilia,
with which its movements were effected; and its companion was the
_Aspidisca lynceus_, an oval animalcule, having a distinct cilia or
_lorica_, and furnished, in addition to cilia, with bristles, which
enable it to walk and climb as well as swim.
There were also some eggs of rotifers attached to the water plants, in
which motion could be descried at intervals, and a little red eye
observed. These eggs are always large in proportion to the creatures
that lay them, and if they escape being devoured by enemies, may be
watched until their contents step forth.
In this, as in other months, omission is made of creatures that have
already come under notice, or our list would assume larger dimensions.
CHAPTER VII.
JUNE AND JULY.
Lindia Torulosa--OEcistes Crystallinus--A professor of
deportment on stilts--Philodina--Changes of form and
habits--Structure of Gizzard in Philodina family--Mr. Gosse's
description--Motions of Rotifers--Indications of a will--Remarks
on the motions of lower creatures--Various theories--Possibility
of reason--Reflex actions Brain of insects--Consensual
actions--Applications of physiological reasoning to the
movements of Rotifers and Animalcules.
A Pressure of other occupations prevented full use being made of June
and July, nor was the weather at all propitious. For this reason the
microscopic doings of these two months are recorded in one chapter.
As usual the Kentish Town ponds were productive of objects, and among
them were several rotifers not found in the previous months. The first
of these was a very small worm-like thing, with one eye, a tuft of cilia
about the mouth, and two toes at the tail end. Had it not been for the
jaws, which were working like fingers thrust against each other, and
which were unmistakably of the rotifer pattern, the animal might have
been supposed to belong to some other class. According to the
'Micrographic Dictionary,' the _Lindia torulosa_ is 1--75" long, but
this specimen was only about 1--200". It was possibly very young, and
did not thrust out its cilia in two distinct tufts, as Cohn describes,
although it may have had the power of doing so. At times it sprang
quickly backwards and forwards, bringing its head where its tail was
before. This object required for its comfortable elucidation a power of
about six hundred linear.
[Illustration: OEcistes crystallinus.]
Among the common water-plants, which are worth examining as the probable
abodes of rotifers or infusoria, is the pretty little thing called
"star-weed," some of which was obtained from the last-mentioned ponds,
and on examination yielded a specimen of a tube-dwelling rotifer, the
_OEcistes crystallinus_, which, although less beautiful than the
Floscules or the Melicerta, is, nevertheless, a pretty and interesting
object. In this instance a little rough dirty tube, about 1--70" long,
was observed to contain an animal capable of rising up and expanding a
round mouth garnished with a wreath of cilia; while a little below, the
indefatigable and characteristic gizzard of the tribe was in full play.
A power of two hundred and forty linear sufficed to afford a good view,
and it was seen that a long, irregular, conical body was supported upon
a short wrinkled stalk. The usual drawings represent this creature with
a short bell-shaped body upon a very long slender pedicle. Possibly this
one might have been able to show himself under this guise, but he did
not attempt it; his appearance being always pretty much as described,
which made the foot shorter and the body longer than the measurements
which naturalists have given, and according to which the whole creature
is 1--36" long, although the body is only 1--140". The tube of the
_OEcistes_ is called a "lorica," or carapace; but it has in truth no
right whatever to the appellation.
Another strange rotifer, of whose name I am uncertain, had an ovalish
oblong body, and a pair of legs like compasses, twice as long as
himself. His antics were those of a posture-master, or "Professor of
Deportment" on stilts. Sometimes he stood bolt upright, bringing his
legs close together; then they were jauntily crossed, and the body
carried horizontally; then the two legs would be slightly opened, and
the body thrown exactly at right-angles to them. These antics were
repeated all the while the observation lasted, and had a very funny
effect in proving that drollery is practised, if not understood, in the
rotatorial world.
[Illustration: Philodina (swimming).]
Another kind of rotifer was abundant--the _Philodina_, which belongs to
the same family as the common wheel-bearer, namely, the _Philodinæa_.
The _Philodina_ is a good deal like the common wheel-bearer, or _Rotifer
vulgaris_, but is usually of a stouter build, and carries his eyes in a
different place. In the common rotifer these organs are situated on the
proboscis, while those of the Philodina are lower, and said to be
"cervical." The changes of form in this rotifer are still more
remarkable than in the common wheel-bearer. When resting it resembles a
pear-shaped purse, puckered in at the mouth. Then it thrusts out its
tail-foot, swells its body to an oval globe, protrudes its feeler, and
slightly exposes a row of cilia. After this two distinct wheels are
everted, and as their cilia whirl and spin, the animal is swiftly rowed
along, until it thinks proper to moor itself fast by the tail-foot, and
employ all its ciliary power in causing currents to converge towards its
throat. When it pleases it can elongate the body, till it becomes
vermiform, and it walks like the common rotifer, by curving its back,
and bringing its nose and its tail in contact with the ground.
[Illustration: Philodina (crawling).]
The gizzard of this family (_Philodinæa_) presents a considerable
deviation from the perfect form exhibited by the _Brachions_. According
to Mr. Gosse, "The _mallei_ and the _incus_ (terms already explained)
are soldered together into two subquadrantic-globular masses, which
appear to be muscular, but invested with a solid integument. The
_manubria_ (handles) may still be recognised in a vertical aspect as
three loops, of which the central one is chiefly developed, and in a
vertical aspect as a translucent reniform (kidney-shaped) globe." These
descriptions are not easy to understand, not from any want of clearness
or precision in the words employed, but from the complicated character
of the organ, and its very different appearance under different aspects.
To make the matter more intelligible, Mr. Gosse adds, "the structure and
action of an apparatus of this type may be made more clear by a homely
illustration. Suppose an apple to be divided longitudinally, leaving the
stalk attached to one half. Let this now be split again longitudinally
so far as the stalk, but not actually separating either portion from it.
Draw the two portions slightly apart, and lay them down on their rounded
surfaces. They now represent the quadrantic masses in repose, the stalk
being the fulcrum, and the upper surfaces being crossed by the teeth. By
the contraction of the muscles, of which they are composed, the two
segments are made to turn upon their long axis, until the points of the
teeth are brought into contact, and the toothed surfaces rise and
approach each other. The lower edges do not, however, separate as the
upper edges approach, but the form of the mass alters, becoming more
lenticular, so that when the toothed surfaces are brought into their
closest approximation, the outline has a subcircular figure. It is on
account of this change of form that I presume the masses themselves to
be partially composed of muscle."
These remarks, although specially made of the _Rotifer macrurus_, are in
the main applicable to all the Philodinas, but the student must not
expect to understand any of the complicated gizzards of the rotifers
without repeated observations, and no small exercise of patience. It is
common to call the portions of the Philodine-pattern gizzard
"stirrup-shaped," but Mr. Gosse has shown them to be _quadrantic_, that
is, shaped like the quarter of a sphere.
As we are not very well off with subjects for description in these two
months, we can afford a little time to consider a question that
continually arises in the mind, on viewing the movements of animalcules,
and especially of any so highly developed as the rotifers, namely, to
what extent motions which appear intelligent are really the result of
anything like a conscious purpose or will. When any of the lower
animals--a bee, for example--acts in precisely the same way as all bees
have acted since their proceedings have been observed, we settle the
question by the use of the term _instinct_. Those who take the lowest
view of insect life, assume that the bee flies because it has wings, but
without wishing to use them, and that the nerves exciting them to action
are in their turn excited, not by volition, but by some physical
stimulus.
The sight or the smell of flowers is thought by the same reasoners to be
capable of attracting the insect, which is unconscious of the
attraction, while proximity of food stimulates the tongue to make the
movements needful for its acquisition, and so forth. The cells, they
tell us, are built according to a pattern which the earliest bee was
impelled to construct by forces that bear no analogy to human reason and
human will, and so originate all the ordinary processes of bee life.
Sometimes, however, it happens that man or accident interposes
particular obstacles, and forthwith there appears a particular
modification of the orthodox plan, calculated to meet the special
difficulty. How is this? Does any one of the difficulties which the bee
or the ant is able to get over, produce precisely that kind of
electrical disturbance, or polar arrangement of nerve particles that is
necessary to stimulate the _first_ step of the action by which the
difficulty is surmounted; and does the new condition thus established
stimulate the _second_ step, and so forth, or can the bee, within
certain limits, really _think_, design, and contrive?
No questions are more difficult of solution; but while protesting
against a tendency to undervalue all life below that of man, we must
remember we have in our bodies processes going on which are not the
result of volition, as when the blood circulates, and its particles
arrange themselves in the pattern required to form our tissues and
organs, and also that many of our actions belong to the class termed by
physiologists, "reflex," that is, the result of external impressions
upon the nervous system, in which the _sentient_ brain takes no part.
Thus when a strong light stimulates the optic nerve, the portion of
brain with which it is connected in its turn stimulates the iris to
contract the pupil; and it is supposed that after a man has begun to
walk, through the exercise of his will, he may continue to walk, by a
reflex action; as his feet press the ground they transmit an impression
to the spinal cord, and the legs receive a fresh impulse to locomotion,
although the mind is completely occupied with other business, and pays
no attention to their proceedings.[14] The ordinary movements of insects
appear to be of this character, and to be excited by the ganglia
belonging to the segment to which the moving limbs are attached. Thus a
centipede will run, after its head has been cut off, and a water-beetle
(_Dytiscus_) swam energetically when thrown into water after its brain
had been removed.[15]
[14] See Carpenter's 'Manual of Physiology.'
[15] Carpenter's 'Manual of Physiology,' p. 551.
It must not, however, be assumed that the brain of insects has nothing
to do with their movements. It is probably the means of co-ordinating or
directing them to a common end, and gives rise to what are called
_consensual_ movements, that is, movements which are accompanied or
stimulated by a sensation, although not controlled by a will. In man
these actions are frequently exhibited, "as when laughter is provoked by
some ludicrous sight or sound, or by the remembrance of such at an
unseasonable hour."[16] Sneezing is another instance of a sensation
leading to certain motions, without any intervention of the human will.
[16] Ibid., p. 543.
Speaking of these consensual motions, Dr. Carpenter observes, "It is
probable, from the strong manifestations of emotion, exhibited by many
of the lower animals, that some of the actions which we assemble under
the general designation of instinctive are to be referred to this
group."
The insect brain is composed of a supra-oesophagal ganglion and
infra-oesophagal one. Von Siebold says, the first corresponds to the
cerebrum of the vertebrata, and "the second is comparable, perhaps, to
the cerebellum or spinal cord."[17] The superior ganglion gives off
nerves to the antennæ and eyes, the lower one to the mandibles, &c. So
far as is known the insects that exhibit the most intelligence have the
largest and best developed brains.
[17] 'Anatomy of Invertebrates,' Burnett's trans.
A special volume would be required for anything like a complete
examination of the little which is known on this subject, but these few
remarks may assist the microscopic beginner in examining the movements
of his subjects, and guard against the error of referring to reason and
volition those which are, probably, either the direct result of
stimulants applied to the surface (as in nerveless creatures), or the
indirect (reflex) result of such stimulants in beings like the rotifers,
who have a nervous system; or the result of _sensations_, which excite
actions without previously referring the matter to the decision of a
will. It must not, however, be too readily assumed that the behaviour of
creatures possessing distinct organs is entirely automatic; and we must
not forget that even the best physiologists know very little concerning
the range of functions which the nervous ganglia of the invertebrata are
able to discharge.
CHAPTER VIII.
AUGUST.
Mud coloured by worms--Their retreat at alarm--A country
duck-pond--Contents of its scum--Cryptomonads--Their means of
locomotion--A Triarthra (three-limbed Rotifer)--The Brachion or
Pitcher Rotifer--Its striking form--Enormous gizzard--Ciliary
motion inside this creature--Large eye and brain--Powerful
tail--Its functions--Eggs.
In the beginning of this month a pond in the Finchley Road, a little
beyond the Highgate Archway, supplied some more specimens of the
_Pterodina patina_, described in a previous chapter; but towards the
middle of the month a visit to Chipstead, in Surrey, enabled a new
region to be explored.
It is always a treat to a Londoner to get down to any of the picturesque
parts of Surrey; the trees exhibit a richness of foliage and variety of
colour not seen within the regions of metropolitan smoke; the distance
glows with the rich purples so much admired in the pictures of Linnel,
and the sunsets light up earth and sky with the golden tints he is so
well able to reproduce. Probably the warmth of the soil, and the purity
of the air, may make Surrey ponds prolific in microscopic life; but of
this we do not know enough to make a fair comparison, although our own
dips into them were tolerably lucky.
Walking one day down a lane leading towards Reigate, where the trees
arched overhead, ferns grew plentifully in the sandy banks, and the
sunlight flitted through the branches, and chequered the path, we came
to a shallow pond, or great puddle, which crossed the way, and near the
edge of the water the eye was struck with patches of crimson colour. On
attempting to take up a portion of one of these patches the whole
disappeared, although when the disturbance ceased the rich colour again
clothed the dingy mud. The appearance was caused by thousands of little
worms, belonging to the genus _Tubifex_, not uncommon in such
situations, who thrust themselves out to enjoy the light and air, and
retreat the moment an alarm is given. Probably both actions belong to
the class described in the last chapter, as "reflex;" but it would be
interesting to know whether creatures so humble have any sense of fear.
These worms will repay observation, but in these pages we eschew all
their tribe--unless the rotifers be assigned to them--and take ourselves
once more to our especial subjects.
[Illustration: Cryptomonad--Euglena.]
Knowing that farm-ponds are usually well stocked with microscopic game,
we made a dip into one more especially assigned to ducks, and obtained
wondrous little for our pains. We were not, however, discouraged, but
made an examination of the circumstances, which determined a particular
course of action. Our piece of water was simply a dirty duck-pond, in
which no large plants were growing, and which did not even exhibit the
little disks of duckweed that are common to such situations. There was,
however, on the surface, in parts, an exceedingly fine scum of pale
yellow green, and this, armed with a teaspoon, we proceeded to attack.
By careful skimming, a small bottle was half-filled with minute organic
particles, which were likely to be interesting in themselves, and pretty
sure to be the food for something else. A small drop was placed on a
tablet of the live-box, flattened out by the application of the cover,
and viewed with a power of two hundred linear, which disclosed swarms of
brilliant green globes, amongst which were a good sprinkle of minute
creatures, like the _Euglenæ_ already described, and whose little red
eyes contrasted vividly with the prevailing emerald hue.
[Illustration: Cryptomonad.]
One of the higher infusoria, whose species I could not identify, was
devouring them like a porpoise among sprats. It did not, however,
exhibit any sense in its hungry career; it moved about in all
directions, gulping down what came in its way, but often permitting the
escape of the little green things that were almost in its mouth. The
little globes rolled and whirled about without the faintest indication
of a purpose, and without exhibiting any instrument with which their
locomotion was effected. To find out how this was done, a higher power
was used, and from their extreme minuteness an amplification of seven
hundred and twenty linear was conveniently employed, although a lower
one (three or four hundred) disclosed the secret by showing that a
little whip was flourished about through the neck, which the lower power
revealed. When highly magnified, each little globe was seen to consist
of an outer case of a reddish orange colour, which was noticeable on
looking at the edges, although in the centre it was transparent enough
to show the brilliant green contents, that resembled the chlorophyll, or
green colouring matter of plants. From a short neck proceeded the
whip-like filament, which was lashed and twisted about in all
directions. These little creatures belong to the monad family, but
whether they are to be called _Trachelomonads_, or by some other hard
name, the learned must decide.
The 'Micrographic Dictionary' puts a note of interrogation to the
assertion of some writers that _Trachelomonads_ have no necks, and draws
some with such an appendage.
Pritchard's last edition is against necks, and whether the necks or no
necks are to win, is a mighty question equal at least to the famous
controversy, which divided the world into "big and little endians in the
matter of breaking eggs."
A discussion of more importance is, whether these _Cryptomonads_--that
name will do whatever comes of the neck controversy--are animals or
vegetables. Lachmann and Mr. Carter affirm that they have detected a
contractile vesicle, which would assimulate them to the animal series,
but their general behaviour is vegetable; and the 'Micrographic
Dictionary' is in favour of referring them to the _Algæ_--that great
family of simple plants, of which the sea-weeds are the most important
representatives.
[Illustration: Triarthra.]
When any of the monads swarm, there are sure to be plenty of other
creatures to eat them up, and in this instance the predaceous
animalcule, already described, was not the only enemy the little green
globes had to suffer from, as two sorts of rotifer were frequently met
with. One of these was a very handsome and singular creature, which in
some positions had the general contour of a cockatoo, only that the legs
were wanting, and the head exhibited a monkey face. The "wheels" were
represented by ciliary tufts, and two bright red eyes twinkled with a
knowing look. From each shoulder proceeded a long curved spine, and
about two thirds down the body, and lying between the two long spines, a
shorter one was articulated, which followed the same curve. A gizzard
was busy in the breast, and the body terminated in two short toes, which
grasped a large round egg. Whenever the cilia were drawn in, the three
spines were thrown up; but they had an independent motion of their own,
and every now and then were jerked suddenly and violently back, which
occasioned a rapid change in the creature's position. The gizzard
appeared to consist of two rounded masses, having several ridges of
teeth, which worked against each other something like the prominences of
a coffee-mill. From the three spines, this animal was a _Triarthra_, or
Three-limbed Rotifer, but the position of the spines, and the toes, made
it differ from any species described in the 'Micrographic Dictionary,'
or in Pritchard.
Whether or not this species is to be regarded as having a lorica or not,
must depend upon the precise meaning attached to that word. At any rate
the integument was much firmer than in many of the rotifers, and gave an
efficient support to the spines which a mere skin could not do. As Mr.
Gosse remarks of an allied genus, the _Polyarthra_, or Many-limbed
Rotifer, this creature could not be investigated without coming to the
conclusion "Here again we have true jointed limbs;" a fact of great
importance in determining the zoological rank of the family, and in
supporting Mr. Gosse's view some at least bore a strong affinity with
the group of _Arthropoda_, of which the insects are the principal
representatives.
[Illustration: Brachionus urceolaris. This drawing has been accidentally
reversed by the engraver, which alters the relative place of the
internal organs.]
Another rotifer of even greater interest, which was busy among the
Cryptomonads, was the Brachion, or "Pitcher Rotifer" (Brachionus). The
members of this genus will frequently reward the searcher into
pond-life. Their main characteristic is a cup or pitcher-shaped lorica,
which is cut or notched at the top into several horns or projections,
the number of which indicates the species; while two or more similar
projections ornament the bottom. This lorica is like the shell of a
tortoise open at both ends; from the top an extremely beautiful wreath
of cilia is protruded, and also some longer and stiff cilia, or slender
spines, which do not exhibit the rotatory movement. The ciliary
apparatus is in reality continuous, but it more often presents the
appearance of several divisions, and the lateral cilia frequently hang
over the sides. From the large size of each cilium they are very
favorable creatures for exhibiting the real nature of the action, which
gives rise to the rotatory appearance, and which can be easier studied
than described. By movements, partly from their base, and partly arising
from the flexibility of their structure, the cilia come alternately in
and out of view, and when set in a circular pattern, the effect is
amazingly like the spinning round of a wheel. The internal arrangements
of the Brachiones are finely displayed, and they have a most aldermanic
allowance of gizzard, which extends more than half way across each side
of the median line, and shows all the portions described by Mr. Gosse.
As the joints of this machine move, and the teeth are brought together,
one could fancy a sound of mill-work was heard, and the observer is
fully impressed with a sense of mechanical power.
When the creature is obliging enough to present a full front view, her
domestic economy is excellently displayed. The prey that is caught in
her whirlpool is carried down by a strong ciliary current to the
gizzard, which may be often seen grappling with objects that appear much
too big for its grasp; and Mr. Gosse was lucky in witnessing an attempt
to chew up a morsel that did actually prove too large and too tough, and
which, after many ineffectual efforts, was suddenly cast out. As soon as
food has passed the gizzard, it is assisted in its journey by more
ciliary currents, which are noticeable in the capacious stomach, in the
neighbourhood of which the secreting and other vessels are readily
observed. Just over the gizzard blazes a great red eye, of a square or
oblong form, and it reposes upon a large mass of soft granular-looking
brain, which well justifies Mr. Gosse's epithet "enormous." Whether this
brain is highly organized enough to be a _thinking_ apparatus, we do not
know, but it is evidently the cause of a very vigorous and consentaneous
action of the various organs the Brachion possesses.
A description of the Brachion would be very incomplete if it omitted
that important organ the tail, which in this family reaches the highest
point of development. It is a powerful muscular organ, of great size in
proportion to the animal, capable of complete retraction within the
carapace, and of being everted wholly, or partially, at will. It
terminates in two short conical toes, protruded from a tube-like sheath,
and capable of adhering firmly even to a substance so slippery as glass.
This tail may be observed to indicate a variety of emotions, if we can
ascribe such feelings to a rotifer, and it answers many purposes. Now we
see it cautiously thrust forth, and turned this way and that, exploring
like an elephant's trunk, and almost as flexible. Now it seizes firm
hold of some substance, and anchors its proprietor hard and fast. A few
moments afterwards it lashes out right and left with fury, like the tail
of a cat in a passion. Then again it will be retracted, and a casual
observer might not imagine the Brachion to be furnished with such a
terminal implement.
The Brachiones may often be seen with one or more large eggs stuck
about the upper part of the tail, and others may be discerned inside.
One specimen before us has three eggs attached to her in this way. They
are large oval bodies, with a firm shell. These creatures differ very
much in appearance, according to the direction in which they are seen,
and a side view makes them look so different from a full front or back
aspect, that it would be easy to suppose another animal was under
observation. The extent to which the ciliary apparatus is protruded, and
the pattern it forms likewise differs continually; and hence no drawing,
however correct, is sure to resemble the arrangement that may be
presented to the observer's eye. But however our little "Pitcher" may be
viewed, it is sure to prove a spectacle of interest and delight.
CHAPTER IX.
SEPTEMBER.
Microscopic value of little pools--Curious facts in appearance
and disappearance of Animalcules and Rotifers--Mode of
preserving them in a glass jar--Fragments of Melicerta
tube--Peculiar shape of Pellets--Amphileptus--Scaridium
Longicaudum--A long-tailed Rotifer--Stephanoceros Eichornii--A
splendid Rotifer--Its gelatinous bottle--Its crown of
tentacles--Retreats on alarm--Illumination requisite to see its
beauties--Its greediness--Richly-coloured Food--Nervous ganglia.
Scattered about Hampstead Heath are a number of little pools, not big
enough to be dignified by the name of ponds. They are generally
surrounded by furze bushes, and would escape attention if not actually
looked for. Those which are mere puddles, and have only a brief
existence in rainy weather, seldom reward the labour of investigation;
but others are permanent, except after prolonged drought, and afford
convenient situations for the growth of confervæ, star-weed, and other
plants. These will nearly always repay the microscopic collector during
the winter, when he must break the ice to get at their contents; in
spring, when long chains of frog-spawn afford ocular evidence of the
prolific properties of the Batrachian reptiles; and in summer, when
they afford both shade and sunshine to their numerous inhabitants. Small
beetles, water-spiders, larvæ of gnats, and other insects, rotifers,
including the tubicolar sorts, and several varieties of infusoria may be
expected and generally found. There is, however, a curious fact about
ponds, big and little, which Pritchard remarks upon in his 'Infusoria,'
and which corresponds with our own experience, that those which have
proved to be well stocked with any particular creature during one year,
will very likely contain none of it in the next. There are of course
exceptions to this rule, but we have often been astonished and
disappointed at finding the complete change, both in populousness and
population, that a revolution of twelve months will make; and it would
be extremely interesting to notice the changes that took place during a
term of years.
Such researches might unfold some unexpected laws in the succession of
infusorial life. Those germs which are most widely diffused, will be the
most likely to be developed in any mass of convenient water; but how and
why the rarer forms come and go is very imperfectly understood. Slight
modifications in surrounding circumstances will materially affect the
result. Thus, if we bring home a handful of conferva, and a few
water-plants of higher organisation, such as duckweed and anacharis, and
place the whole in a glass jar full of pond-water, we shall at first
have a good stock of objects; but they will usually grow less and less,
until scarcely anything is left. If, however, we introduce a few pieces
of straw, or a tiny wisp of hay, we shall succeed much better, and not
only preserve our population longer, but enjoy a succession of animated
crops. Extensive decomposition of vegetable matter kills off all but
certain families, such as Paramecia, who enjoy it; on the other hand,
too little decomposition proves fatal to some creatures, by depriving
them of their food, and when they have died off, those who depended upon
them for a living, die too. Different vegetables in decomposition suit
different creatures, and hay and straw in that state seem to please the
largest number. An animalcule tank will succeed best when it contains
two or three kinds of growing plants, which oxygenize the air, and a
moderate variety of decomposing organisms will supply food without
making the water offensive.
From these considerations it will be apparent that not only the nature
of the vegetation of a pond, which is often changed by accidental
circumstances, but also the quality of the odds and ends that the winds
may blow into it, or which may fall through the air, will do much to
determine the character and number of its inhabitants, while the
quantity of shade or sunshine it enjoys, will also exercise an important
influence. Hay and other infusions have from the beginning of
microscopic investigations been employed to obtain the creatures which
the Germans call "Infusions thierchen" (infusion animalcules), and the
English "Infusoria;" but very little has yet been done in the way of
their scientific culture and management.
To return from this digression to our little Hampstead ponds, we
obtained from one, in September, that was full of star-weed, a number of
sugar-loaf bodies, adhering to one another, and of a pale yellow brown
colour. The specimens first examined looked complete in themselves, and
were taken for eggs of some water creature. Further search, however,
disclosed aggregations of similar sugar-loaves that had evidently formed
part of a tubular structure, and the idea at once occurred that they
were fragments of a Melicerta tube, a conclusion that was verified by
finding some tubes entire and a dead Melicerta in the rubbish at the
bottom. All the specimens of Melicerta tubes we had hitherto examined
were composed of _rounded_ pellets, but these were made of pointed cones
or sugar-loaves, with the points projecting outwards from the general
surface. In Pritchard's 'Infusoria,' these pellets are described "as
small lenticular bodies." The 'Micrographic Dictionary' states that the
tubes of the Melicerta are composed of "numerous rounded or discoidal
bodies;" and Mr. Gosse, in his 'Tenby,' which contains an admirable
description, and an exquisite drawing of this interesting rotifer, calls
the pellets "round."
[Illustration: Melicerta ringens.]
Not being able to obtain a living specimen of the Melicerta, who made
her tube of long sugar-loaves, I could not tell whether she differed in
structure from the usual pattern of her race, but the general appearance
of the dead body was the same. It is possible that these creatures
possess some power of modifying the form of their singular bricks, or
they may at different ages vary the patterns, which matters some
fortunate possessor of a colony of these animals may be able to
verify.
[Illustration: Scaridium longicaudum.]
In the sediment of the water containing the Melicerta cases was found an
animalcule about 1--120" long, covered with cilia, and having a
proboscis seldom more than a quarter of the length assumed by the body,
which continually changed its form, sometimes elongating, sometimes
shortening, and often contracting one side into a deep fissure. It was,
probably, an _Amphileptus_, though not precisely agreeing with any
drawing or description I am acquainted with. Another inmate of the same
water was a lively long-tailed rotifer, with a small oval body, a tuft
of vibrating cilia and a curved bristle visible among them on one side.
This creature had a jointed tail-foot, ending in two long style-shaped
toes, and by means of this appendage executed rapid leaps or springs. It
was the _Scaridium longicaudum_, and agreed in dimensions tolerably well
with the size given in the books, namely, total length 1--72". With a
power of five hundred diameters the muscles of the tail-foot presented
a beautifully striated appearance.
Towards the end of the month I passed the Vale of Heath Pond, Hampstead,
and although I had not gone out for the purpose of collecting, was
fortunately provided with a two-dram bottle. Close by the path the
_Anacharis alsinastrum_ grew in profusion, quantities of water-snails
crawled among its branches, and small fish darted in and out, threading
their mazes with lightning rapidity. Thrusting a walking-stick among the
mass of vegetation, a few little tufts were drawn up and carefully
bottled, with the addition of a little water. Returning home, a few
leaves were placed in the live-box, and on examination with the power of
sixty diameters they disclosed a specimen of, perhaps, the most
beautiful of all the rotifers, the _Stephanoceros Eichornii_. In this
elegant creature an oval body, somewhat expanded at the top, is
supported upon a tapering stalk, and stands in a gelatinous bottle,
composed of irregular rings superimposed one upon the other, as if
thrown off by successive efforts, the upper ones being inverted and
attached to the body of the animal. But that which constitutes the glory
of this little being is the crown of five tapering tentacles, each
having two rows of long cilia arranged on opposing sides, but not in the
same plane. The ordinary position of the tentacles is that of a graceful
elliptical curve, first swelling outwards, then bending inwards, until
their points closely approximate, but each is capable of independent
motion, and they are seldom quiet for many minutes at a time. The cilia
can be arranged in parallel rows or in tufts at the will of the
creature, and their motion appears under control, and susceptible of
greater modification than is exhibited by the ordinary infusoria.
[Illustration: Stephanoceros Eichornii.]
The Stephanoceros is a member of the Floscule family, but in all the
specimens I obtained and watched for several weeks, there was an
important difference in the relation of the tube to the creature. In the
Floscules I had never seen anything like an adhesion between the tube
and the animal, but in the Stephanoceros I noticed it continually, and
always in the manner already described. Like the Floscule, the
Stephanoceros is readily alarmed, and retreats into her house, carrying
with her the invaginated portion. In the last edition of 'Pritchard's
Infusoria,' this case is spoken of as apparently not tubular, but a
solid gelatinous mass, enveloping the animal as high up as the base of
the rotatory arms. It is very likely that specimens at different ages,
and possibly in different seasons, may vary in the structure of their
abodes; but I am not able to concur in the preceding account, as all the
tubes I examined resembled sacks turned in at the mouths, and attached
to the shoulders only of their inmates; and on one occasion I was able
to look down into a deserted tube, which had not collapsed, as it would
have done if it had been merely a solid gelatinous mass.
Like the Floscule, the Stephanoceros only reveals her beauties under
careful illumination. A direct light renders them invisible, and only
when the requisite obliquity has been obtained, does the exquisite
character of the structure become displayed. The dark-ground
illumination is very useful, and makes the ciliary action very distinct.
At times a view can be obtained, in which the cilia of perhaps a single
tentacle are all ranged like the steel springs of a musical box. For a
moment they are quiescent, and then they vibrate in succession, each
moving thread sparkling in the light. With a clumsy mode of lighting
them, the cilia look like stumpy bristles, and are often so drawn; but
precisely the right quantity of light coming in the right direction,
makes them appear more numerous, and much longer than would at first be
supposed. When well exhibited the tentacles have a lustre between glass
and pearl; the body, in a favorable specimen, is like a crystal cup, and
the food, usually composed of small red and green globes, glows like
emeralds and rubies, as if in the height of luxury the little epicure
had more than rivalled Cleopatra's draught, and instead of dissolving,
swallowed its jewelry whole. So lustrous and varied in colour is the
whole appearance of the animal under these circumstances, that it is
frequently alluded to by one of our first artists, to whom it was
displayed.
It is said by some authors that the tentacles are used to seize prey.
This never occurred under my observation, although their basal portions
are often approximated when an object is forced down to the grinding
apparatus below. The Stephanoceros is a ravenous feeder, and swallows a
variety of creatures. Green vegetable monads, rich red and brown globes
of similar characters, and any animalcule that comes in her way is
acceptable; and even good-sized rotifers do not escape her
all-consuming maw. On one occasion I noticed one of the loricated sort,
more than half as long as one of her tentacles, rapidly swallowed, and
passed downwards without attempting to escape. Objects much too big for
the gizzard are often gulped down, and probably receive a preliminary
softening and maceration in the crop. Very often, when food is
plentiful, the creature is filled to the brim, but still endeavours to
continue her abundant meal. From the presence of large quantities of
food and the density of the integuments, the gizzard cannot always be
seen; but in favorable specimens its teeth may be observed busily at
work.
At the base of the tentacles small masses of matter may be discovered,
which are probably nervous ganglia, and other organs; and Ehrenberg
discovered small vibrating bodies, supposed to be connected with the
function of respiration. A single egg, as shown in the annexed drawing,
is often found, and the ovarian is said to develop but few at a time.
Two red eyes are found in young specimens, but in adults they either
disappear or are not conspicuous. The Stephanoceri are sociable animals,
and when one is found, others are probably near at hand. Several may
often be discovered on the same branch of a small water-plant, of
various dimensions, and in different stages of growth. The full size is
about 1--36" in height, and from its magnitude care is required not to
crush it in the live-box. When specimens are plentiful, some should be
placed in that convenient receptacle; and others with the plant on which
they are growing, in a glass cell or trough, where they have more room
to display their motions, and can with fresh supplies of water, be
preserved for days and weeks. With occasional renewals from one pond, I
was able to keep up a stock for about three months, and never had
objects which gave more pleasure to myself or to my friends.
CHAPTER X.
OCTOBER.
Stentors and Stephanoceri--Description of Stentors--Mode of
viewing them--Their abundance--Social habits--Solitary Stentors
living in Gelatinous caves--Propagation by divers
modes--Cephalosiphon Limnias--A group of Vaginicolæ--Changes of
shape--A bubble-blowing Vorticella.
October, the finest of our autumn months, is noted for usually granting
the inhabitants of our dripping climate about twenty pleasant sunshiny
days, and it is probably on this account somewhat of a favourite with
the infusorial world, although the cold of its nights and early mornings
thins their numbers, which reach a maximum in the summer heat. Even in
the dismal year 1860, October maintained its character, and afforded a
great many opportunities of animalcule hunting, during which a constant
supply of Stephanoceri were readily obtained, together with swarms of
_Stentors_, which are not exceeded in interest by any of the Ciliated
Protozoa. The Stentors were abundant on the same weed (_Anacharis_),
that formed the residence of the Stephanoceri, and might be seen in
large numbers hanging from it like green trumpets, visible to the
unassisted eye. In the 'Micrographic Dictionary' they are said to
belong to the Vorticella family, which has already given us several
beautiful objects, and possess a marvellous power of changing their
shape. It is, however, better to follow Stein, who separates them from
the Vorticellids and ranges them in his order Heterotricha, as they have
two distinct sets of cilia, small ones covering the body and the larger
ones round the mouth. Those before us are named after this property
_Stentor polymorphus_,[18] or Many-shaped Stentors, and owe their
exquisite tint to numberless green vesicles, or small cavities filled
with colouring matter like that of plants. This, however, is not
essential to the species which may often be found of other hues. In size
this Stentor varies from a hundred and twentieth to one twenty-fourth of
an inch. It is entirely covered with fine cilia, disposed in
longitudinal rows, and round the head is a spiral wreath of larger and
very conspicuous cilia leading to the mouth.
[18] See Frontispiece.
Having observed the abundance of these creatures, a few small branches
to which they were appended, were placed in the glass trough, and viewed
with powers of sixty and one hundred linear. Some had tumbled down as
shapeless lumps, others presented broad funnel-shaped bodies; while
others stretched themselves to great length like the long, narrow
post-horns which still wake the echoes of a few old-fashioned towns. The
ciliary motion of the elegant wreath was active and rapid, causing quite
a stir among all the little particles, alive and dead; and when the
right sort of food came near the corkscrew entrance to the mouth, down
it went, and if conspicuous for colour, was subsequently seen apparently
embedded in little cavities, which Ehrenberg supposed were separate
stomachs, although that theory is now rejected. One advantage of viewing
these objects in a sufficient quantity of water, to leave them in
freedom, is that they frequently turn themselves, so that you can see
right down into them; and the drawing given in the frontispiece
represents such a view, which is the most favorable for the exhibition
of the mouth. To make out the details of their structure, to see the
nucleus and other organs, the flattening in the live-box is useful, and
it enables much higher powers to be employed.
[Illustration: A, B, C, D, Stentor polymorphus in different degrees of
expansion. A large specimen is one twenty-fourth of an inch long.]
After leaving the Anacharis in a glass jar for a few days, the Stentors
multiplied exceedingly; some clung to the sides of the vessel in
sociable communities, others hung from the surface of the water, and
crowds settled upon the stems, visibly changing their tint, as the
Stentor green was much bluer than that of the plant. Scores swam about
in all sorts of forms. Now they looked like cylindrical vessels with
expanding brims, now globular, now oddly distorted, until all semblance
of the original shape was lost. Many were found in shiny tubes, but
these were never so lively or green as the free swimmers, but mostly of
a dingy dirty hue.
These housekeepers were more timid and cautious than the roving tribe.
They came slowly out of their dens, drew back at the slightest alarm,
never took their tails from home, and only extended their full length
when certain not to be disturbed. Some authors have thought they only
take to private lodgings when they feel a little bit poorly, but others
dispute this opinion, and I do not think it is correct. I have found
these Stentors at all seasons, from January to the autumn, but they are
never so numerous, nor aggregated in numbers like the roving sort.
Whether they are old folks, who are tired of the world and its gaieties,
and devote the remainder of their lives to contemplation, or whether
they are bachelors disappointed in love, I am unable to say; but they
are very inferior in beauty to the "gay and glittering crowd."[19]
[19] Stein says the colourless variety of S. Polymorphus is sometimes
found with a tube, and the S. Rössellii very frequently so provided.
For some weeks my Stentors abounded, and then most of them suddenly
disappeared. They could not have "moved," but probably "went to smash"
by a process peculiar to infusoria, and which Dujardin politely
describes as "diffluence." This mode of making an exit from the stage of
life is more tragical than the ripping up so fashionable in Japan. The
integument bursts, and its contents disperse in minute particles, that
in their turn disappear, and scarcely leave a "wrack behind."
The Stentors obey the injunction to "increase and multiply" by
self-division, which Stein says is always oblique, and the nucleus,
which plays such an important part in infusoria, is band-like,
moniliform (bead-shape), or round. When an animalcule increases by
self-division, a portion of the nucleus goes with each part, and it is
probably the organ which stimulates the change. It is also concerned in
other modes of propagation. "The anus is situated on the back close
beneath the ciliary circle;" and the "contractile vesicle on a level
with the ciliary wreath." Stein records that in November, 1858, he met
green Stentors (_Polymorphus_) encysted, and he figures one in a
gelatinous flask having a stopper in its narrow neck.
Before closing our account of the Stentor, let us revert a moment to the
ciliary wreath, as it may be made the subject of a curious experiment.
If, for example, the cilia are viewed at right-angles to their length,
they will seem to form a delicate frill, in which a quivering motion is
perceived. But if the table is shaken by a sharp blow, the frill is
thrown into waves, or takes the form which washerwomen give to certain
female articles by the use of the Italian iron, and the ciliary motion
is thus made to take place in different planes, and rendered strikingly
apparent.
One day turning over the Anacharis in search of subjects, a small brown
tube was noticed, from which a glassy rod protruded like the feeler of a
rotifer. Keeping the table quiet, and watching the result, was soon
rewarded by a further protrusion of the feeler, accompanied by a portion
of the body of the inmate of the tube. The feeler was thrust on this
side and on that, as if collecting information for its proprietor, who,
I suppose, was satisfied with the intelligence, and gradually extended
herself, until she stood out two thirds in length beyond the tube, and
set two lobes of one nearly continuous ciliary organ in rapid motion.
Sometimes the creature, _Cephalosiphon limnias_, bent its neck, if I may
so speak, to the right, and sometimes to the left, and sometimes stood
upright, when the true form of the ciliary apparatus could be seen. The
tube of this creature was opaque, from the adhesion of foreign matter,
and presented an untidy appearance, strangely contrasting with the
clear, neat bottles of the Floscules. These Cephalosiphons are very
whimsical in their ways, and many that were sent to different observers
never exhibited their ciliary wreaths, but performed sundry antics,
disguising their true shape.
[Illustration: Cephalosiphon limnias.]
Somewhat like the Cephalosiphon, though much commoner and without the
siphon, is Limnias ceratophylli, which every collector is sure to meet.
The length of the Limnias varies, according to Pritchard, from 1--20" to
1--40". Our Cephalosiphon, when fully extended and magnified one hundred
and eighty linear, looked about three inches and a half long, and was
therefore very small. Just below the ciliary lobes the gizzard was seen,
with its toothed hammers working one against the other. The masticatory
organ differs from the typical form, as represented in the Brachion; and
Mr. Gosse observes of Limnias that "each _uncus_ forms, with its
_ramus_, a well-defined mass of muscle enclosing the solid parts, and in
form approaching the quadrature of a globe. Across the upper surface of
the mass the _uncus_ is stretched like three long parallel fingers,
arched in their common direction, and imbedded in the muscular
substances, their points just reaching the opposing face of the _ramus_,
and meeting the points of the opposite _uncus_ when closed."[20]
[20] The terms _uncus_, _ramus_, etc., have been explained in Chapter
II, page 28.
There is no connection between Limnias or Cephalosiphon and their tubes,
except that of simple adhesion, which takes place by means of the end of
their foot-stalks.
In a former chapter we have described an interesting relation of the
Vorticella, the Cothurnia, whose elegant crystal vases form a very
artistic abode, characterised by possessing a distinct foot. Other
species of the same family inhabit vases which have no foot or stalk, or
live in gelatinous sheaths less accurately fashioned. Sometimes these
creatures are obliging enough to conform to the specific descriptions
which eminent naturalists have given of them, and also to the characters
which the authorities have assigned to the different genera in which
they have been grouped, but the microscopist will often meet with
difficulties in the way of classification.
[Illustration: Vaginicola (?) (A, elongated; B, retracted.)]
Attached to a piece of weed were a number of cylindrical masses of
brownish jelly, with rounded tops, and situated in an irregular and very
transparent sheath, about twice as high as themselves. Presently they
all rose up to four times their previous height, put forth a beautiful
crown of vibrating cilia, and opened a sort of trap-door to their
internal arrangements. In this position they had a long cylindrical
form, gracefully curved, but of nearly equal width from the mouth to the
base, and they readily imbibed particles of carmine, which tinged sundry
little cavities with its characteristic hue. The slightest disturbance
caused the ciliary wreaths to be drawn in, and the bodies to be
retracted, and descend into their house like a conjuring toy, until the
appearance first described was reproduced.
The general form and structure of these objects was like the drawings
usually given of _Vaginicola_, which is said not to exist in groups,
although two individuals are commonly found in one well-shaped cell.
These creatures, however, did not taper towards the base as Vaginicolæ
generally do, and perhaps they became aware of this defect in their
figures, for after a day or two a change appeared, and they assumed a
more graceful form by swelling out in the middle, and then growing
slender down to the bottom, very much like the pattern given by
glass-blowers to little vases of flowers.
It is very important to note the changing appearance of animalcules, and
where the same individuals can be observed from day to day, these will
often be found considerable. It is probable that when such particulars
are fully known, the number of species will be greatly reduced, and the
study of these organisms considerably simplified. I have called the
animals just described _Vaginicolæ_, but the reader must be prepared to
find similar bodies, inhabiting well-formed vases, either solitarily or
in couples, the latter condition arising from the fission of one
individual without a corresponding division of the abode.
For a few weeks I continually met with groups living as I have
described, in what may be called amorphous cells, which were often so
nearly like the surrounding water in refracting power, as to be
discerned with some difficulty. No trace could be seen of divisions
into separate cells, but they all appeared to live happily together in
one room, and if one went up all went up, and if one went down all went
down, as if their proceedings were regulated by a community of sensation
or will.
Another little curiosity was a transparent cup upon a slender stem,
which stood upright like a wineglass, and supported on its mouth a
transparent globe. By removing a leaf which prevented the stalk being
traced to its termination, it was found to be a Vorticella, and after
two hours the globe was partially drawn in, and reduced in size. Why the
creature was engaged in blowing this bubble I do not know, and have not
met with another instance of such conduct.
CHAPTER XI.
NOVEMBER.
Characteristics of the Polyzoa--Details of structure according
to Allman--Plumatella repens--Its great beauty under proper
illumination--Its tentacles and their cilia--The mouth and its
guard or epistome--Intestinal tube--How it swallowed a Rotifer,
and what happened--Curiosities of digestion--Are the tentacles
capable of Stinging?--Resting Eggs, or "Statoblasts"--Tube of
Plumatella--Its muscular Fibres--Physiological importance of
their structure.
During the fag end of last month I observed some fragments of a new
creature among some bits of Anacharis, from the Vale of Heath Pond, and
searched for complete and intelligible specimens without effect. Luckily
one evening a scientific neighbour, to whom I had given some of the
plant for the sake of the beautiful _Stephanoceri_ which inhabited it,
came in with a glass trough containing a little branch, to which adhered
a dirty parchment-like ramifying tube, dotted here and there with brown
oval masses, and having sundry open extremities, from which some
polyp-shaped animals put forth long pearly tentacles margined with
vibrating cilia, and making a lively current. The creatures presented an
organization higher than that of polyps, for there was an evident
_differentiation_ and complication of parts. They belonged to the
_Polyzoa_ or _Bryozoa_,[21] a very important division of the _mollusca_.
The _Polyzoa_ are chiefly marine, and the common "sea-mat," often
erroneously treated as a _sea-weed_, is a well-known form. A species of
another order often picked up on our coasts is the _Sertularia_, or
Sea-Fir, composed of delicate branching stems of a horny-looking
substance, which, under a pocket-lens, is found to contain an immense
number of small cells inhabited by Polyps. It is instructive to compare
the two and note how much more advanced in structure is the Polyzoon
than the polyp.
[21] _Polyzoa_ means "many animals," in allusion to their habit of
living in association. _Bryozoa_, "moss-animals," from some forming
cells having that appearance.
[Illustration: Plumatella repens. Single Polypide enlarged]
Polyzoa were formerly associated with the polyps, to which they bear a
strong superficial resemblance; but they are of a much higher degree of
organization, as will be seen by comparing what has been said in a
former chapter on the _Hydra_, with the description which we now proceed
to abridge from Dr. Allman's splendid monograph on the fresh-water
kinds. In order to get a general conception of a Polyzoon, the Professor
tells us to imagine an alimentary canal, consisting of oesophagus,
stomach, and intestine, to be furnished at its origin with long ciliated
tentacles, and to have a single nervous ganglion on one side of the
oesophagus. We must then conceive the intestine bent back till its
anal orifice comes near the mouth; and this curved digestive tube to be
suspended in a bag containing fluid, and having two openings, one for
the mouth and the other for the vent. A system of muscles enables the
alimentary tube to be retracted or protruded, the former process pulling
the bag in, and the latter letting it out. The mouth of the bag is, so
to speak, tied round the creature's neck just below the tentacles, which
are the only portions of it that are left free. The investing sack has
in nearly every case the power of secreting an external sheath, more or
less solid, and which branches forming numerous cells, in which the
members of the family live in a socialistic community, having, as it
were, two lives, one individual, and the other shared in common with the
rest.
The whole group of tubes and cells, whatever may be the form in which
they are aggregated, is called the _Polypary_, or, as Dr. Allman
prefers, the _Coenoecium_ (common house); the creature he names a
_Polypide_[22] (polyp-like); and the disk which bears the tentacles
_Lophophore_ (crest-bearer). There are some more hard words to be learnt
before the student can enjoy himself scientifically among the Polyzoa,
and we shall be compelled to employ some of them before we have done;
but will now endeavour to describe what was presented to our view by the
specimen obtained from the Hampstead Pond.
[22] _Polyzoon_ is preferable, as avoiding confusion with _polypite_,
used for another class of object.
The general aspect of a branch of _Plumatella repens_--the creature we
have to describe--is given in the drawing annexed. When all was quiet,
the mouths of the bags belonging to each cell were slowly everted, and
out came a numerous bundle of tentacles, which were either spread like
the corolla of a flower, or permitted to hang dishevelled like the
snake-locks of Medusa. We will suppose these organs symmetrically
expanded, and that we are looking down upon them with a magnifying power
of sixty diameters, the light having been carefully adjusted by turning
the reflecting mirror a little on one side, to avoid a direct glare. The
tentacles, each of which curves with a living grace, and displays an
opaline tint in its glassy structure, do not form a complete circle, for
at one place we discern two slightly diverging arms of the disk, or
frame (Lophophore) from which they grow.
These arms support tentacles on each side, and leave a gap between, so
that the whole pattern is _crescentic_, or crescent-shaped, and not
circular. Extending as far as the points of the arms, and carried all
round the crescent, is an extremely delicate membrane, like the finest
gauze, which unites all the tentacles by their basal portions, and makes
an elegant retreating curve between every two. Each tentacle exhibits
two rows of cilia, which scintillate as their vibrations cause them to
catch the light. The motion of the cilia is invariably _down_ one side
and _up_ the other, the current or pattern being carried on from one
tentacle to the other, all through the series. This characteristic, and
the facility with which each cilium can be distinguished, gives great
interest and beauty to the spectacle of this wonderful apparatus, by
which water-currents are made to bathe the tentacles, and assist
respiration, and also to carry food towards the mouth, over which a sort
of finger or tongue is stretched to guard the way, and exercise some
choice as to what particles shall be permitted to pass on. This organ is
called the _epistome_, from two Greek words, signifying "upon the
mouth."
If the cell is an old one, it may be covered with so much extraneous
matter as to obscure the economy within; but we are fortunate in having
a transparent specimen before us, through which we can see all that goes
on. The alimentary tube, after forming a capacious cavity, much longer
than it is broad, turns round and terminates in an orifice near the
mouth, and just below the integuments. When refuse has to be discharged,
this orifice is protruded; and after the operation is over, it draws
back as before. Long muscles, composed of separate threads or fibres,
pull the creature in and out of its cell, and at the part where the
stomach ends, and the intestine turns round, is attached a long flexible
rope, called the _funiculus_, which goes to the bottom of the cell. The
passage of the food down to the stomach, its digestion, and the eviction
of the residue, can all be watched; and when a large morsel is
swallowed, the spectacle is curious in the extreme.
One day a polyzoon caught a large rotifer, (_R. vulgaris_,) which, with
several others of its tribe, had been walking over the _coenoecium_,
and swimming amongst the tentacles, as if unconscious of danger. All of
a sudden it went down the whirlpool leading to the mouth, was rolled up
by a process that could not be traced, and without an instant's loss of
time, was seen shooting down in rapid descent to the gulf below, where
it looked a potato-shaped mass, utterly destitute of its characteristic
living form. Having been made into a bolus, the unhappy rotifer, who
never gave the faintest sign of vitality, was tossed up and down from
the top to the bottom of the stomach, just as a billiard-ball might be
thrown from the top to the bottom of a stocking. This process went on
for hours, the ball gradually diminishing in size, until at last it was
lost in the general brown mass with which the stomach was filled. The
bottom of the stomach seems well supplied with muscular fibres, to cause
the constrictions by which this work is chiefly performed, and by
keeping a colony for a month or two, I had many opportunities of seeing
my Polyzoa at their meals.
When alarmed the tentacles were quickly retracted, but although these
creatures are said to dislike the light, and usually keep away from it
in their native haunts, my specimens had no objection to come out in a
strong illumination, and seemed perfectly at their ease. They were
indeed most amiable creatures, and never failed to display their charms
to admiring visitors, who rewarded them with unmeasured praise. Twice I
had an opportunity of observing an action I cannot explain, except by
supposing either that the tentacles of the _Plumatella_ have some
poisonous action, or that rotifers are susceptible of fear. On these
occasions the common rotifer was the subject of the experiment. First
one and then another got among the tentacles, and on escaping seemed
very poorly. One fellow was, to borrow a phrase from Professor Thomas
Sayers, "completely doubled up," and two or three seconds--long periods
in a rotifer's life--elapsed before he came to himself again.
By keeping a colony of the Plumatella for a few weeks in a glass trough,
and occasionally supplying them with fresh water from an aquarium,
containing the animalcules, they are easily preserved in good health,
and as they develop fresh cells, the process of growth may be readily
watched. This production of fresh individuals enlarges the parent
colony, but could not be the means of founding a new one, which is
accomplished by two other modes. A little way down the cells Professor
Allman discovered an ovary attached to the internal tube by a short
_peduncle_, or foot stalk, while a testis or male generative organ is
attached to the _funiculus_, or "little rope," we have already
described.
July and August are the best times for observing the ovaries, and they
are most conspicuous in the genera _Alcyonella_ and _Paludicella_. True
eggs are developed in the ovaries in a manner resembling this mode of
multiplication in other animals; but there is another kind of egg, or,
perhaps to speak more properly, a variety of bud, which is extremely
curious. In looking at our specimens we noticed brown oval bodies in the
cells; these, on careful examination, presented the appearance of the
sketch. The centre is dark, covered with a network, which is more
conspicuous in the lighter coloured and more transparent margins. These
curious bodies are produced from the funiculus, and act as reserves of
propagative force, as they are not hatched or developed until they get
out and find themselves exposed to appropriate circumstances. Professor
Allman names them _Statoblasts_, or stationary germs, and they bear some
resemblance to what are called the "winter eggs" of some other
creatures. The Professor was never able to discover any mode by which
they were permitted to escape from the cells, and in our colonies none
were allowed to leave their homes until the death of their parent, and
the decomposition of its cell had taken place; a process which went on
contemporaneously with the growth of new cells, until the plant on which
the _coenoecium_ was situated, rotted away, and then unfortunately
the whole concern went to pieces.
[Illustration: Plumatella repens on a leaf.]
The tubes of the _Plumatella_, and of most other Polyzoa, are composed
of two coats, called respectively _endocyst_ and _ectocyst_, that is,
"inner case" and "outer case." The first is vitally endowed, and
exhibits vessels and muscular fibres. The second or outer case is thrown
off by the first. It is a parchment-like substance, strengthened by the
adhesion of dirt particles, and does not appear to exercise any vital
functions, but to be merely a covering for protection. The inner layer
terminates in the neck of the bag before described, as exserted when the
polypide comes out, and inverted when it goes in. This mode of making a
case or sheath by inversion of a bag is technically called
_invagination_, and is readily seen in new and transparent cells.
The movement of _eversion_, or coming out, is chiefly produced by the
contraction of the endocyst; while the _inversion_, or getting in again,
is performed by the long muscles, which, when the animal is extended,
are seen attached to it like ropes. Upon these muscles Professor Allman
remarks that they are "especially interesting in a physiological point
of view, as they seem to present us with an example of true muscular
tissue, reduced to its simplest and essential form. A muscle may here
be viewed as a beautiful dissection far surpassing the most refined
preparation of the dissecting needle, for it is composed of a bundle of
elementary fibres, totally separate from one another through their
entire course." He further adds, "The fibres of the great retractor
muscle are distinctly marked by transverse striæ;--a condition, however,
which is not at all times equally perceptible, and some of our best
observers have denied to the Polyzoon the existence of striated fibre."
We can confirm the fact of this sort of fibre being present, but we
fancy a reader not versed in the mysteries of physiology exclaiming,
'What does it matter whether his fibres are striped or not?'
Physiologists used to suppose there was a strong and marked distinction
and separation between _striped_ muscles, that is, muscles the fibres of
which exhibit transverse stripes when magnified, and those which do not.
Kölliker, however, says this decided separation can no longer be
maintained,[23] and he gives instances in proof of the connections that
can be traced between the two forms. In the higher animals the striped
muscles are the special instruments of _will_, and of movements that
follow, or are accompanied by, distinct sensations. Striped fibre must
be regarded as the highest form; and as a muscle of this sort contracts
in length it increases uniformly in breadth.
[23] 'Manual of Human Microscopic Anatomy,' p. 63.
There are many other genera and species of fresh-water polyzoa besides
the _Plumatella repens_, and they are found attached to sticks, stones,
or leaves, generally to the under surface of the latter. They are all
objects of great interest and beauty, which, whatever their diversity,
conform sufficiently to one type that the student who has observed one,
will easily recognise the zoological position of another. They should be
viewed by transmitted and by dark-ground illumination, which produces
very beautiful effects. To observe them in the performance of their
functions, they require more room than the live-box can afford, but are
well shown in the glass trough, whose moveable diaphragm enables them to
be brought near enough to the object-glass, for the use of a power of
about sixty linear for general purposes, and of from one to two hundred
for the examination of particular parts. For a more detailed examination
dissection must be employed, but all that we have mentioned can be seen
without injury to the living animal, if specimens are kept till new
cells are formed in water, which does not contain enough dirt to render
their integuments opaque.
CHAPTER XII.
DECEMBER.
Microscopic Hunting in Winter--Water-bears, or Tardigrada--Their
comical behaviour--Mode of viewing them--Singular gizzard--A
compressorium--Achromatic condenser--Mouth of the
Water-bear--Water-bears' exposure to heat--Soluble
albumen--Physiological and chemical reasons why they are not
killed by heating and drying--The Trachelius ovum--Mode of
swimming--Method of viewing--By dark-ground
illumination--Curious digestive tube with
branches--Multiplication by division--Change of form immediately
following this process--Subsequent appearances.
There is always satisfaction in finding a work accomplished; but the
attempt to delineate some of the marvels of minute creation has been a
pleasant one, and we approach the completion of our task of recording a
_Microscopic Year_ with something like regret. The dark, dirty December
of the great metropolis may not seem a promising time for field
excursions, but some ponds lie near enough to practicable roads and
paths to render an occasional dip in them, not of ourselves, but of our
bottles--an easy and not unpleasant performance; and if the weather is
unusually bad, we can fall back upon our preserves in bottles and tanks,
which seldom fail to afford something new, as we have been pretty sure
to bring home some undeveloped germs with our stock of pond-water and
plants, and even creatures of considerable size are very likely to have
escaped detection in our first efforts at examination.
When objects are not over abundant, as is apt to be the case in the cold
months, it is well to fill a large vial with some water out of the
aquarium or other large vessel, and watch what living specks may be
moving about therein. These are readily examined with a pocket-lens, and
with a little dexterity any promising creature can be fished out with
the dipping-tube. It is also advisable to shake a mass of vegetation in
a white basin, as the larger infusoria, &c., may be thrown down; and
indeed this method (as recommended by Pritchard) is always convenient.
Even so small a quantity of water as is contained in a glass cell,
appropriated to the continual examination of polyps or polyzoa, should
be frequently hunted over with a low power, as in the course of days and
weeks one race of small animals will disappear, and another take their
place.
Following these various methods in December, we obtained many specimens;
but the most interesting was found by taking up small branches of the
Anacharis with a pair of forceps, and putting them into a glass trough
to see what inhabitants they might possess. One of these trials was
rewarded by the appearance of a little puppy-shaped animal very busy
pawing about with eight imperfect legs, but not making much progress
with all his efforts. It was evident that we had obtained one of the
_Tardigrada_ (slow-steppers), or Water-Bears, and a very comical amusing
little fellow he was. The figure was like that of a new-born puppy, or
"unlicked" bear cub; each of the eight legs were provided with four
serviceable claws, there was no tail, and the blunt head was susceptible
of considerable alteration of shape. He was grubbing about among some
bits of decayed vegetation, and from the mass of green matter in his
stomach, it was evident that he was not one of that painfully numerous
class in England--the starving poor.
[Illustration: Water-Bear.]
A power of one hundred and five linear, obtained with a two-thirds
object-glass, and the second eye-piece, enabled all his motions and
general structure to be exhibited, and showed that he possessed a sort
of gizzard, whose details would require more magnification to bring out.
Accordingly the dipping-tube was carefully held just over him, the
finger removed, and luckily in went the little gentleman with the
ascending current. He was cautiously transferred to a Compressorium,[24]
an apparatus by which the approach of two thin plates of glass can be
regulated by the action of a spring and a screw; and just enough
pressure was employed to keep him from changing his place, although he
was able to move his tiny limbs. Thus arranged, he was placed under a
power of two hundred and forty linear, and illuminated by an achromatic
condenser,[25] to make the fine structure of his gizzard as plain as
possible. It was then seen that this curious organ contains several
prominences or teeth, and is composed of muscular fibres, radiating in
every direction. From the front of the gizzard proceed two rods, which
meet in a point, and are supposed to represent the maxillæ or jaws of
insects, while between them is a tube or channel, through which the food
is passed. The mouth is _suctorial_, and the two horny rods, with their
central piece or pieces, are protrusile. They were frequently brought as
far as the outer lips (if we may so call the margins of the mouth), but
we did not witness an actual protrusion, except when the lips
accompanied them, and formed a small round pouting orifice. The skin of
the animal was tough and somewhat loose, and wrinkled during the
contractions its proprietor made. The interior of the body exhibited an
immense multitude of globular particles of various sizes in constant
motion, but not moving in any vessels, or performing a distinct
circulation.
[24] The best forms of this instrument are made by Messrs. R. & J. Beck,
the glass plates being held in their places by flat-headed screws, and
not by cement. This plan was devised by the author, and makes it easy to
renew the glasses when broken.
[25] The achromatic condenser is a frame capable of supporting an
object-glass, lower than that employed for vision, through which the
light passes to the object in quantities and directions determined by
stops of various shapes. The appearances mentioned can be seen without
it, though not so well.
My specimens had no visible eyes, and these organs are, according to
Pritchard's book, "variable and fugacious." The same authority remarks,
"In most vital phenomena they very closely accord with the rotatoria;
thus like these they can be revived after being put into hot water at
113° to 118°, but are destroyed by immersion in boiling water. They may
be gradually heated to 216°, 252°, and even 261°. It is also by their
capability of resuscitation after being dried that they are able to
sustain their vitality in such localities as the roofs of houses, where
at one time they are subjected to great heat and excessive drought, and
at another are immersed in water."
When vital processes are not stopped by excess of temperature, as is the
case with the higher animals, the power of resisting heat without
destruction depends upon the condition of the albumen. Soluble albumen,
or, as it should be called, _Albuminate of Soda_ (for a small quantity
of that alkali is present and chemically united with it), after having
been _thoroughly dried_, may be heated without loss of its solubility;
although if the same temperature was applied before it was dry, that
solubility would be destroyed, and it would no longer be a fit
constituent of a living creature. As Dr. Carpenter observes, this fact
is of much interest in explaining the tenacity of life in the
Tardigrada.
The movements of the water-bears, although slow, evince a decided
purpose and ability to make all parts work together for one common
object; and as might be expected from this fact, and also from the
repetition of distinct, although not articulated limbs, they are
provided with a nervous apparatus of considerable development, in the
shape of a chain of a ganglia and a brain, with connecting filaments.
From these and other circumstances naturalists consider the Tardigrada
to belong to the great family of _Spiders_, of which they are,
physiologically speaking, _poor relations_. Siebold says "they form the
transition from the Arachnoidæ to the Annelides."[26] Like the spiders
they cast their skin; and, although I was not fortunate enough to
witness this operation--called in the language of the learned _ecdysis_,
which means putting its clothes off--I found an empty hide, which,
making allowance for the comparative size of the creatures, looked tough
and strong as that of a rhinoceros, and showed that the stripping
process extended to the tips of the claws. The 'Micrographic Dictionary'
states that the Tardigrada lay but few eggs at a time, and these are
"usually deposited during the ecdysis, the exuviæ serving as a
protection to them during the process of hatching." Thus Mrs. Water-Bear
makes a nursery out of her old skin, a device as ingenious as
unexpected. The water-bears are said to be hermaphrodites, but this is
improbable.
[26] 'Anatomy of the Invertebrata,' Burnett's trans., p. 364.
The _Plumatella repens_, described in a former chapter, was kept in a
glass trough, to which some fresh water was added every few days, taken
from a glass jar that had been standing many weeks with growing
anacharis in it. One day a singular creature made its appearance in the
trough; when magnified sixty diameters it resembled an oval bladder,
with a sort of proboscis attached to it. At one part it was
longitudinally constricted, and evidently possessed some branched and
complicated internal vessel. The surface was ciliated, and the neck or
proboscis acted as a rudder, and enabled the creature to execute rapid
turns. It swam up and down, and round about, sometimes rotating on its
axis, at others keeping the same side uppermost, but did not exhibit the
faintest sign of intelligence in its movements, except an occasional
finger-like bend of the proboscis, upon which the cilia seemed thicker
than upon the body. It was big enough to be observed as a moving white
speck by the naked eye, when the vessel containing it was held to catch
the light slantingly; but a power of one hundred and five was
conveniently employed to enable its structure to be discerned. Under
this power, when the animal was resting or moving slowly, a mouth was
perceived on the left side of the proboscis, which was usually, though
not always, curved to the right. The mouth was a round or oval orifice,
and when illuminated by the parabola, its lips or margin looked
thickened, and of a pale blue, and ciliated, while the rest of the body
assumed a pinkish pearly tint.
Below the mouth came a funnel-shaped tube or oesophagus, having some
folds or plaits on its sides, and terminating in a broad digestive tube,
distinct from the nucleus, and ramifying like a tree. The constriction
before mentioned, which was always seen in certain positions, although
it varied _very considerably_ in depth and width, drew up the integument
towards the main trunk of the digestive tube, and thus the animal had a
distinct ventral and dorsal side. The branches of the tube stopped
somewhat abruptly just before reaching the surface, and were often
observed to end in small round vacuoles or vesicles.
[Illustration: Trachelius ovum (slightly flattened).]
At the bottom of the bladder, opposite the mouth, in some specimens were
large round cavities or cells, filled with smaller cells, or partially
transparent granules. These varied in number from one to two or three,
and were replaced in other specimens by masses that did not present the
same regular form or rounded outline. In one instance an amorphous
structure of this kind gradually divided itself, and seemed in the
course of forming two cells, but the end of the process was
unfortunately not seen. The annexed drawing will readily enable the
animal to be recognised. It shows the mouth very plainly, and a current
of small particles moving towards it. The oesophagus terminates in a
digestive tube, like the trunk of a tree, from which numerous branches
spring. This arrangement is probably analogous to that of the
phlebenterous mollusks described by Quatrefages, in which the
ramifications of the stomach answer the purpose of arteries, and convey
the nutrient fluid to various parts of the body. It is also likely that
they minister to the function of respiration.
The cilia on the surface, which are arranged in parallel lines, are best
observed when the animal is slightly flattened in a live-box; but this
process produces a considerable derangement in the relative position of
the internal parts, and they can only be well seen when it is immersed
in plenty of water, and is polite enough to stand still, and submit his
digestive economy to a steady gaze. The only way to succeed in this
undertaking is to have a large stock of patience as well as a convenient
cell or trough. The table must be kept steady, and the prisoner watched
from time to time, and at last he will be found ready for display.
Pritchard says this animal, whose name is _Trachelius ovum_, is an
inhabitant of stagnant bog water, and has been found encysted. My
specimens could not be called plentiful, but for several weeks I could
generally find two or three, by filling a four-ounce vial from the glass
jar, and examining its contents with a pocket-lens. If none were
present, another dip was made, and usually with success.
One evening I caught a good specimen by means of the dipping-tube, and
cautiously let it out, accompanied by a drop of water, on the glass
floor of the live-box. A glance with the pocket-lens showed all was
right, and the cover was very gently put on, but it had scarcely touched
the creature when it became crumpled up and in confusion. On one or two
former occasions I had been unfortunate enough to give my captives a
squeeze too much, with the usual result of a rupture of their
integuments and an escape of globules and fluids from the regions
within. Now, however, there was no such rupture and no such escape, but
instead of a smooth, comely surface, my Trachelius had lost all title to
his specific designation, _ovum_, for instead of bearing any resemblance
to an egg, it was more like an Irishman's hat after having a bit of a
"shindy" at Donnybrook Fair.
I was greatly puzzled with this aspect of things, and still more so when
my deranged specimen twirled and bumped about with considerable
velocity, and in all directions. Presently a decided constriction
appeared about half-way below the mouth and proboscis, and in transverse
direction. The ciliary motion became very violent in the lower half just
below the constriction, while the proboscis worked hard to make its half
go another way. For some minutes there was a tug of war, and at length
away went proboscis with his portion, still much crumpled by the fight,
and left the other bit to roam at will, gradually smooth his puckers,
and assume the appearance of a respectable well-to-do animalcule.
[Illustration: _Trachelius ovum_, three hours after division.]
Three hours after the "fission" the proboscis half was not unlike the
former self of the late "entire," but with diminished body and larger
neck; while the remaining portion had assumed a flask form, and would
not have been known by his dearest acquaintance. The portraits of the
_dis-United States_ were quickly taken, and, as bed-time had arrived,
they were left to darkness and themselves. The next morning a change had
come over the "spirit of their dream." Both were quiet, or sedately
moving, and they were nearly alike. The proboscis fellow had increased
and rounded his body, and diminished his nose; while Mr. Flask had grown
round also, and evinced an intention of cultivating a proboscis himself.
Twenty-seven hours after the separation, both had made considerable
progress in arranging and developing their insides, which had been
thrown into great confusion by the way in which the original animal had
been wrenched in half, and in both a granular mass was forming opposite
the mouth end. The proboscis portion, which may perhaps be termed the
_mother_, was more advanced than her progeny, but both had a great deal
to do if they meant to exhibit the original figure, and develop a set of
bowels as elegantly branched. Whether they would have succeeded or not
under happier circumstances I cannot tell, but unfortunately the Fate
who carries the scissors cut short their days.
In all other animalcules in which I had observed the process of
multiplication by self-division, it seemed to go on smoothly, and with
no discomfort to either the dividend or the quotient, and it may be that
in the fission of the _Trachelius ovum_ I witnessed what the doctors
would call a bad case. Indeed it may have been prematurely brought on,
and aggravated by the squeeze in the live-box. It is, however, probable,
from the stronger texture and greater organic development of this
animalcule, that it does not divide so easily as the softer and simpler
kinds.
Frequent examination of this animalcule has created a strong doubt in my
mind whether it is rightly placed in our "systems." My own impression is
that it belongs to a higher class.
CHAPTER XIII.
CONCLUSION.
The creatures described in the preceding pages range from very simple to
highly complicated forms, and in describing them some attention has been
paid to the general principles of classification. The step is a wide one
from the little masses of living jelly that constitute Amoebæ to the
Rotifers, supplied with organs of sensation--eyes, feelers (calcars),
and the long cilia in the Floscularians, which seem to convey impression
like the whiskers of a cat--together with elaborate machinery for
catching, grinding up, and digesting their prey, and which are also well
furnished with respiratory and excretory apparatus, ovaries, &c. In the
polypi and polyzoa may be observed those resemblances in appearance
which induced early naturalists to group them together, and also the
wide difference of organization which marks the higher rank to which the
latter have attained. Amongst the ciliated infusoria important
gradations and differences will also be noticed, some having only one
sort of cilia, others two sorts, and others, again, supplied, in
addition to cilia, with hooks and styles. No perfectly satisfactory
classification of the infusoria has yet been devised, and the life
history of a great many is still very imperfectly known. On the whole,
the tendency of research is to place many of them higher than they used
to stand after Ehrenberg's supposition of their having a plurality of
distinct stomachs, &c., was given up. Balbiani and others have shown
numerous cases of their forming their eggs by a process analogous to
that of higher animals. Some really are, and others closely resemble,
the larval conditions of creatures higher in the scale, and the
contracted vesicle with its channel bears resemblance to what is called
the "water vascular system" of worms.
Zoological classification depends very much on morphology, that is, the
tracing of particular structures, or parts, through all their stages,
from the lowest to the highest forms in which they are exhibited. In
this way the swimming bladder of a fish is shown to be a rudimentary
lung, though it has no respiratory functions, and Mr. Kitchen Parker has
found in the imperfect skull of the tadpole a rudimentary appearance of
bones belonging to the human ear. The comparative anatomist, after a
wide survey of the objects before him, arranges them into groups. He
asks what are the characteristic things to be affirmed concerning all
the A's that cannot be said of all the B's; or of all the C's that marks
their difference from the A's or the D's. Careful investigation upon
these methods shows affinities where they were not previously
expected--birds and reptiles being close relations, for example, instead
of distant connections--and they lessen the value for purposes of
classification of peculiarities that might have been deemed of the
highest importance.
Professor Huxley divides the vertebrates into ITHYCOIDS, comprising
fishes and amphibia, which, besides other characteristics, have gills at
some period of their existence; SAUROIDS (reptiles and birds), which
have no gills, and possess certain developmental characteristics in
common; and, lastly, MAMMALS. The Insecta, Myriopoda, Arachnidæ, and
Crustacea, he remarks, "without doubt present so many characters in
common as to form a very natural assemblage. All are provided with
articulated limbs attached to a segmented body skeleton, the latter,
like the skeleton of the limbs, being an 'exoskeleton,' or a bordering
of that layer which corresponds with the outer part of the vertebrates.
In others, at any rate in the embryonic condition, the nervous system is
composed of a double chain of ganglia, united by longitudinal
commissures, and the gullet passed between two of these commissures. No
one of the members of these four classes is known to possess vibratile
cilia. The great majority of these animals have a distinct heart,
provided with valvular apertures, which are in communication with a
peri-visceral cavity containing corpusculated blood." These four classes
have constituted the larger group or "province" of _Articulata_ or
_Arthropoda_. Professor Huxley thinks that, notwithstanding "the marked
differences" between the Annelida (worms) and the preceding Arthropods
(joint-foots), their resemblances outweighing them--"the characters of
the nervous system, and the frequently segmented body, with imperfect
lateral appendages of the Annelida, necessitates their assemblage with
the Arthropoda in one great division, or sub-kingdom, of ANNULOSA."
Tracing analogies between the Echinodermata (sea urchins, star-fish,
&c.) and the Scolecida (intestinal worms), he places them together as
_Annuloida_.
Cephalopoda, Pteropoda, Pulmo-gasteropoda, and Branchio-gasteropoda,
having resemblances of nervous system, and "all possessing that
remarkable buccal apparatus, the Odontophore," are placed together by
him as ODONTOPHORA. The Odontophores (tooth-bearers) are familiar to
microscopists as the so-called _palates_ of mollusca. Placing with the
above the lamellibranchial mollusks (mollusks with gills formed of
lamellæ or little plates), Ascidioida (ascidians), Brachiopoda
(lamp-sheds), and Polyzoa, in spite of their differences, he forms
another great group, ANNULOIDA.
The Actinozoa (anemonies, &c.) and the Hydrozoa (polyps) constitute the
COELENTERA of Frey and Leuckart. "In all these animals," says
Professor Huxley, "the substance of the body is differentiated into
those histological elements which have been termed cells, and the latter
are previously disposed in two layers, one external and one internal,
constituting the ectoderm and endoderm. Among animals which possess this
histological structure the Coelenterata stand alone in having an
alimentary canal, which is open at its inner end and communicates freely
by this aperture with the general cavity of the body," and "all (unless
the Ctenophora should prove a partial exception to the rule) are
provided with very remarkable organs of offence or defence, called
thread-cells or nematocysts." In describing the Polyps we have given
illustrations of these weapons.
The remaining classes, which have been roughly associated as _Protozoa_,
must evidently be rearranged. Sponges, Rhizopods (Amoebæ, &c.), and
Gregarines, have strong resemblances, but recent researches may place
the former higher. The Infusoria comprehend creatures too various to
remain under one head, and very many of them too highly organized to be
called "protozoons," or first life-forms.
Those who wish to pursue this subject further may consult Professor
Huxley's 'Elements of Comparative Anatomy,' from which the preceding
quotations have been taken.
A system of classification founded upon anatomical and developmental
considerations frequently differs considerably from one we might arrive
at if all the creatures were arranged according to the perfection of
their faculties and the extent and accuracy of their relations to the
external world. Such a classification would not in any way supersede the
former, but it would prove very instructive and offer many valuable
suggestions. Some years since, Professor Owen proposed to divide the
Vertebrates according to the perfection of their brains, but other
anatomists did not find his divisions sufficiently coincident with
facts. Very little has been done towards an exact science of human
phrenology. The difficulties remain pretty much as they were many years
ago, and our comparative phrenology, if we may use such a term, is in a
very imperfect state. When we come to the lower animals we do not know
what peculiarities of the brain of an ant make it the recipient of a
higher instinct, or give its possessor greater capacities for dealing
with new and unexpected difficulties than are possessed by most other
insects, and if any reader has a marine aquarium, and will make a few
experiments in taming prawns, and watching their proceedings, he will
discover symptoms of intelligence beyond what the structure of the
creature would have led him to expect.
Animals usually possess some one leading characteristic to which their
general structure is subordinated. Man stands alone in having the whole
of his organization conformed to the demands of a thinking, ruling
brain. To pass at once to the other extreme, we observe in the lower
infusoria a restless locomotion, probably subservient to respiration,
but utterly inconsistent with a well developed life of relation, or with
manifestations of thought. The life of an animalcule may be summed up as
a brief and restricted, but vigorous organic energy, and if the amount
of change which a single creature can make in the external world, is
inconceivably small, the labours of the entire race alter the conditions
of a prodigious amount of matter. Microscopic vegetable life is an
important agent in purifying water from the taint of decomposing
organisms. By evolving oxygen it brings putrescent particles under the
influence of a species of combustion, which, though slow, is as
effectual as that which a furnace could accomplish. In this way minute
moulds burn up decaying wood.
Microscopic animal life helps the regenerative process, and, together
with the minute vegetable life, restores to the organic system myriads
of tons of matter, which death and decay would have handed over to the
inorganic world. In a very small pond or tank the quantity of this kind
of work is soon appreciable, and if we reflect on the amazing amount of
water all over the globe, including seas and oceans, which swarm with
infusoria, the total effect produced in a single year must seem
considerable, even when compared with that portion of the earth's crust
that is subject to alteration from all other causes put together. If we
add to the labour of the Infusoria those of other creatures whose
organization can only be discovered by the microscope, and take in the
foraminifera, polyps, polyzoa, &c., we shall have to record still larger
obligations to minute forms of living things. The coral polyp builds
reefs that constitute the chief characteristic of certain regions in the
Pacific; foraminifera are forming or helping to form strata of
considerable extent, while diatoms are making deposits many feet in
thickness, composed of myriads of their silicious shells, or adding
their contributions of silex, very large in the aggregate, to all
sedimentary rocks. Testimony of this kind of work is found by the
navigator who examines the ice in arctic seas, and it comes up with
soundings from the ocean depths.
On the surface of the earth the amount of change produced is equally
remarkable, although it leaves less permanent traces behind. As a rule
no decomposition of organized matter takes place, no death of plants or
animals, without infusorial life making its appearance, and disposing of
no small portion of the spoil. Even in our climate the mass of matter
thus annually affected is very large; but what must it not be in moist
tropical lands, where every particle seems alive, and the race of life
and death goes on at a speed, and to an extent scarcely conceivable by
those who have not witnessed it.
Thus, if we look at the world of minute forms which the microscope
reveals, there opens before us a spectacle of boundless extent. We see
life manifested by the specks of jelly containing particles not
aggregated into structure, and we see it gradually ascending in
complexities of organization. In creatures whose habits and appearance
seem most remote from our own, we find the elementary developments of
the organs and powers that constitute our glory, and give us our power.
Such studies assist us to conceive of the universe as a Cosmos, or
Beautifully Organized Whole; and, although we cannot tell the object for
which a single portion received its precise form, we trace everywhere
relations of structure to means of existence and enjoyment, and are led
to the conviction that all the actions and arrangements of the organic
or inorganic worlds are due to a definite direction and co-ordination of
a few simple forces, which implicitly and unerringly obey the dictates
of an Omniscient Mind.
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"Combines amusement with instruction in a way that must please
the rising generation."--_Renfrewshire Independent._
LOST IN THE WOOD; AND OTHER STORIES.
BY MRS. GILCHRIST.
Illustrated with 15 Wood Engravings. Foolscap 8vo, cloth gilt, 1_s._
"Perfectly healthy in tone, and highly interesting, these tales
are indeed most suitable for family reading."--_Gloucester
Mercury._
RAINBOW'S REST; AND OTHER STORIES.
BY THOMAS HOOD.
Illustrated with 15 Wood Engravings. Foolscap 8vo, cloth gilt, 1_s._
"These are excellent stories for children, and nicely got up and
illustrated."--_Paisley Herald._
A COMPLETE SET OF THE TWENTY VOLUMES, VIZ.:--
UNION JACK. By Mrs. S. C. HALL.
TOWN OF TOYS. By SARA WOOD.
NO MAN'S LAND. By T. MILLER.
SEA SPLEENWORT. By Author of "The Heir of Redclyffe."
LOTTIE'S HALF-SOVEREIGN. By Mrs. RUSSELL GRAY.
THE SHEPHERD LORD. By JULIA CORNER.
THE CAPTIVE'S DAUGHTER. By W. HEARD HILLYARD.
THE ORPHANS OF ELFHOLM. By FRANCES BROWNE.
WHEN WE WERE YOUNG. By Author of "A Trap to Catch a Sunbeam."
NOT CLEVER. By FRANCES M. WILBRAHAM.
DEAR CHARLOTTE'S BOYS. By EMILY TAYLOR.
STORY OF NELSON. By W. H. G. KINGSTON.
BLIND URSULA. By Mrs. WEBB.
SEA-SHELL ISLAND. By G. E. SARGENT.
WHICH WAS THE BRAVEST? By L. A. HALL.
THE CLOCKMAKER OF LYONS. By E. M. PIPER.
THE ANGEL UNAWARES. By MARY HOWITT.
HISTORICAL DRAMAS. By Author of "The Heir of Redclyffe."
LOST IN THE WOOD. By Mrs. GILCHRIST.
RAINBOW'S REST. By THOMAS HOOD.
Enclosed in a Box, 20s.
"We have read most of them with great care, for we are very
watchful over books for the young, and can assure our readers
they are well worth a mother's attention. They vary in interest
and in moral value, but all of them are calculated both to amuse
and instruct. Some convey valuable historical information,
others lessons in natural history, and most of them convey a
healthy moral influence. All are subservient to religion as well
as morals, but they are not tinctured with any _ism_, nor do
they inculcate any peculiar tenets."--_British Mothers'
Journal._
GROOMBRIDGE & SONS, 5, PATERNOSTER ROW, LONDON.
GROOMBRIDGE'S SHILLING PRACTICAL MANUALS.
_Each Book sent post-free on receipt of the price._
1. HOME-MADE WINES. How to Make and Keep them, with remarks on
preparing the fruit, fining, bottling, and storing. By G. VINE.
Contains Apple, Apricot, Beer, Bilberry, Blackberry, Cherry,
Clary, Cowslip, Currant, Damson, Elderberry, Gooseberry, Ginger,
Grape, Greengage, Lemon, Malt, Mixed Fruit, Mulberry, Orange,
Parsnip, Raspberry, Rhubarb, Raisin, Sloe, Strawberry, Turnip,
Vine Leaf, and Mead.
2. CARVING MADE EASY; or, Practical Instructions for Diners
Out. Illustrated with Engravings of Fish, Flesh, and Fowl, and
appropriate instructions, whereby a complete and skilful
knowledge of the useful art of Carving may be attained, and the
usages of the Dinner Table duly observed. By A. MERRYTHOUGHT.
3. COTTAGE COOKERY. Containing Simple Instructions upon Money,
Time, Management of Provisions, Firing, Utensils, Choice of
Provisions, Modes of Cooking, Stews, Soups, Broths, Puddings,
Pies, Fat, Pastry, Vegetables, Modes of Dressing Meat, Bread,
Cakes, Buns, Salting or Curing Meat, Frugality and Cheap
Cookery, Charitable Cookery, Cookery for the Sick and Young
Children. By ESTHER COPLEY.
4. COTTAGE FARMING; or, How to Cultivate from Two to Twenty
Acres, including the Management of Cows, Pigs, and Poultry. By
MARTIN DOYLE. Contains, On Enclosing a Farm, Land Drainage,
Manures, Management of a Two-acre Farm, Cow Keeping, The Dairy,
Pig Keeping, Bees and Poultry, Management of a Ten-acre Farm,
Flax and Rape, Management of a Farm of Twenty Acres, Farm
Buildings, etc.
5. SINGING MADE EASIER FOR AMATEURS, explaining the pure
Italian Method of Producing and Cultivating the Voice; the
Management of the Breath; the best way of Improving the Ear;
with much other valuable information equally valuable to
Professional Singers and Amateurs.
6. MARKET GARDENING, giving in detail the various methods
adopted by Gardeners in growing the Strawberry, Rhubarb,
Filberts, Early Potatoes, Asparagus, Sea Kale, Cabbages,
Cauliflowers, Celery, Beans, Peas, Brussels Sprouts, Spinach,
Radishes, Lettuce, Onions, Carrots, Turnips, Water Cress, etc.
By JAMES CUTHILL, F.R.H.S.
7. CLERK'S DICTIONARY OF COMMERCIAL TERMS; containing
Explanations of upwards of Three Hundred Terms used in Business
and Merchants' Offices. By the Author of "Common Blunders in
Speaking and Writing Corrected."
"An indispensable book for all young men entering a
counting-house for the first time."
8. THE CAT, Its History and Diseases, with Method of
Administering Medicine. By the Honourable LADY CUST.
9. ELOCUTION MADE EASY for Clergymen, Public Speakers, and
Readers, Lecturers, Actors, Theatrical Amateurs, and all who
wish to speak well and effectively in Public or Private. By
CHARLES HARTLEY. Contents: Cultivation of the Speaking Voice,
Management of the Voice, Pausing, Taking Breath, Pitch,
Articulation, Pronunciation, The Aspirate, The Letter R,
Emphasis, Tone, Movement, Feeling and Passion, Verse, Scriptural
Reading, Stammering and Stuttering, Action, Acting, Reciting,
etc.
10. ORATORY MADE EASY. A Guide to the Composition of Speeches.
By CHARLES HARTLEY. Contents: Introduction, Power of Art,
Various Kinds of Oratory, Prepared Speech, Constructing a
Speech, Short Speeches, Command of Language, Reading and
Thinking, Style, Hasty Composition, Forming a Style, Copiousness
and Conciseness, Diction or Language, Purity and Propriety,
Misapplied Words, Monosyllables, Specific Terms, Variety of
Language, Too Great Care about Words, Epithets, Precision,
Synonymes, Perspicuity, Long and Short Sentences, Tropes and
Figures, Metaphor, Simile, etc.
11. THE GRAMMATICAL REMEMBRANCER; or, Aids for correct
Speaking, Writing, and Spelling, for Adults. By CHARLES HARTLEY.
Contents: Introduction, Neglect of English Grammar, Divisions of
Grammar, Parts of Speech, The Article, The Silent H, Nouns,
Formation of the Plural, Genders of Nouns, Cases of Nouns,
Comparison of Adjectives, Personal Pronouns, Relative Pronouns,
Demonstrative Pronouns, Regular and Irregular Verbs, Shall and
Will, The Adverb, Misapplication of Words, Division of Words,
Capital Letters, Rules for Spelling, Double _l_ and _p_, A Short
Syntax, Punctuation, etc.
12. THE CANARY. Its History, Varieties, Management, and
Breeding, with Coloured Frontispiece. By RICHARD AVIS. Contains,
History of the Canary, Varieties of the Canary, Food and General
Management, Cages, Breeding, Education of the Young, Mules,
Diseases, etc.
13. BIRD PRESERVING and Bird Mounting, and the Preservation of
Birds' Eggs, with a Chapter on Bird Catching. By RICHARD AVIS.
14. WINE GUIDE; or, Practical Hints on the Purchase and
Management of Foreign Wines, their History, and a complete
catalogue of all those in present use, together with remarks
upon the treatment of Spirits, Bottled Beer, and Cider. To which
is appended Instructions for the Cellar, and other information
valuable to the Consumer as well as the Dealer. By FREDERICK C.
MILLS.
GROOMBRIDGE & SONS, 5, PATERNOSTER ROW, LONDON.
ELEGANT PRIZE OR GIFT BOOK FOR BOYS.
In Three handsome Volumes, fcap. quarto, gilt edges, Illustrated
with Eleven Hundred Beautiful Engravings, price Twenty-four
Shillings.
RECREATIVE SCIENCE
A RECORD AND REMEMBRANCER OF INTELLECTUAL OBSERVATION IN EVERY
DEPARTMENT OF SCIENCE.
ASTRONOMY, CHEMISTRY, BOTANY, GEOLOGY, MECHANICS, METEOROLOGY,
MICROSCOPY, PHYSIOLOGY, ZOOLOGY, etc., etc.
THE PROMINENT FEATURES OF RECREATIVE SCIENCE.
APPLICATIONS OF SCIENCE, including Photography and the
Stereoscope, Electro-Metallurgy, etc., with all their minute and
recreative manipulations.
ESSAYS ON THE RESULT OF SCIENTIFIC RESEARCH, as witnessed by the
civilization of the Nineteenth Century, which derives so much of
its strength and moral excellence from the STEAM-ENGINE, the
ELECTRIC TELEGRAPH, and other applications of scientific
principles.
BIOGRAPHIES OF EMINENT SCIENTIFIC MEN AND ANALYSIS OF OLD AND
NEW SCIENTIFIC BOOKS.
ILLUSTRATIONS OF NATURAL PHENOMENA and Diagrams of Optical,
Mechanical, and other principles as required by the subject
matter of the papers published in the work.
NATURAL HISTORY occupies a prominent position among the various
subjects dealt with, including HOME RECREATIONS, of which the
love of Nature may be said to be the basis. The Management of
Collections of Living Animals, the Preparation of Specimens by
Taxidermy, and the arrangement of Cabinets of Insects, Birds,
Shells, Plants, etc., etc.
EXPERIMENTAL PHILOSOPHY AND RECREATIONS IN CHEMISTRY are
introduced with a view to explain principles and give a zest to
study.
RECREATIVE SCIENCE is in all respects popular in tone and
attractive in its subjects. It is compiled by writers of the
highest eminence in the several departments of Scientific
Knowledge. In a word, it is a Record of Discovery, Observation,
and Intellectual Progress. An Instructor in First Principles,
and an Exhibitor of the Accomplishments of Research.
GROOMBRIDGE & SONS, 5, Paternoster Row, London.
Crown 8vo, elegantly bound, cloth gilt, Illustrated with 8 beautifully
coloured full-page Plates and numerous Wood Engravings, price 3s. 6d.
THE MICROSCOPE
A Popular Description of some of the most Beautiful and Instructive
Objects for Exhibition.
With Directions for the Arrangement of the Instruments and the
Collection and Mounting of Objects.
BY THE HON. MRS. WARD.
"This elegant book deserves at our hands especial commendation
for many reasons. There is no book that we know of that we would
more willingly place in the hands of a beginner to create an
interest in the science of Microscopy. The Illustrations are
beautiful, coloured to represent nature, and all original. To
our readers we cannot give better advice than to become
purchasers of the book--they will not regret the
outlay."--_Electrician._
GROOMBRIDGE & SONS, 5, Paternoster Row, London.
Crown 8vo, elegantly bound, cloth gilt, Illustrated with 12 beautifully
coloured full-page Plates and numerous Wood Engravings, price 3s. 6d.
THE TELESCOPE A FAMILIAR SKETCH
COMBINING A SPECIAL NOTICE OF OBJECTS COMING WITHIN THE RANGE OF A SMALL
TELESCOPE
With a Detail of the most Interesting Discoveries which have been made
with the assistance of powerful Telescopes, concerning the Phenomena
of the Heavenly Bodies.
BY THE HON. MRS. WARD.
"It is with pleasure that we direct the reader's attention to a
little gem lately published by the Hon. Mrs. WARD. One of the
most admirable little works on one of the most sublime subjects
that has been given to the world. The main design of the book is
to show how much may be done in astronomy with ordinary powers
and instruments. We have no hesitation in saying that we never
saw a work of the kind that is so perfect. The illustrations are
admirable, and are all original."--_Western Daily Press._
GROOMBRIDGE & SONS, 5, Paternoster Row, London.
Crown 8vo, elegantly bound, cloth gilt, Illustrated with 8 full-page
coloured Plates and numerous Wood Engravings, price 3s. 6d.
COUNTRY WALKS OF A NATURALIST WITH HIS CHILDREN.
BY THE REV. W. HOUGHTON, M.A., F.L.S.
"A fresher, pleasanter, or more profitable book than this has
rarely issued from the press."--_Art Journal._
"Contrives to furnish a large amount of interesting natural
history in brief compass and in a picturesque and engaging
manner."--_Pall Mall Gazette._
"It is wonderful what a very large amount of most instructive
matter connected with the animal and plant world the writer has
condensed into a small compass."--_Land and Water._
"This pretty little volume forms one of the best little books on
popular Natural History, and is admirably adapted as a present
to the young"--_Birmingham Daily Journal._
GROOMBRIDGE & SONS, 5, Paternoster Row, London.
Crown 8vo, elegantly bound, cloth gilt, Illustrated with 8 beautifully
coloured full-page Plates and numerous Wood Engravings, price 3s. 6d.
SEA-SIDE WALKS OF A NATURALIST WITH HIS CHILDREN.
BY THE REV. W. HOUGHTON, M.A., F.L.S.
"The wonders of the sea-shore are detailed in an easy, pleasant
and lucid style."--_Examiner._
"The book is very attractive, and its usefulness is enhanced by
its many careful illustrations."--_Daily Telegraph._
"Families visiting the sea-side should provide themselves with
this convenient and instructive work."--_The Queen._
"It is pleasingly written, and the scientific information is
correct and well selected."--_Athenæum._
GROOMBRIDGE & SONS, 5, Paternoster Row, London.
Crown 8vo, elegantly bound, cloth gilt, Illustrated with 8 beautifully
coloured full-page Plates and 90 Wood Engravings, price 3s. 6d.
FIELD FLOWERS A HANDY BOOK FOR THE RAMBLING BOTANIST, SUGGESTING WHAT TO
LOOK FOR AND WHERE TO GO IN THE OUTDOOR STUDY OF BRITISH PLANTS.
BY SHIRLEY HIBBERD, F.R.H.S.
"It will serve as an excellent introduction to the practical
study of wild flowers."--_The Queen._
"We cannot praise too highly the illustrations which crowd the
pages of this handbook; the coloured plates are especially
attractive, and serve to bring before us very distinctly the
most prominent flowers of the field, the heaths, and the
hedgerows."--_Examiner._
GROOMBRIDGE & SONS, 5, Paternoster Row, London.
Crown 8vo, elegantly bound, cloth gilt, illustrated with 8 beautifully
coloured Plates and 40 Wood Engravings, price 3s. 6d.
THE FERN GARDEN HOW TO MAKE, KEEP, AND ENJOY IT OR, FERN CULTURE MADE
EASY.
BY SHIRLEY HIBBERD, F.R.H.S.
CONTENTS.
FERNS IN GENERAL
FERN COLLECTING
HOW TO FORM AN OUTDOOR FERNERY
CULTIVATION OF ROCK FERNS
CULTIVATION OF MARSH FERNS
FERNS IN POTS
THE FERN HOUSE
THE FERNERY AT THE FIRESIDE
MANAGEMENT OF FERN CASES
THE ART OF MULTIPLYING FERNS
BRITISH FERNS
CULTIVATION OF GREENHOUSE
STOVE FERNS
SELECT GREENHOUSE FERNS
SELECT STOVE FERNS
TREE FERNS
FERN ALLIES
GROOMBRIDGE & SONS, 5, Paternoster Row, London.
Crown 8vo, elegantly bound, gilt edges, Illustrated with 12 beautifully
coloured Engravings, price 3s. 6d.
THE CANARY
ITS VARIETIES, MANAGEMENT, AND BREEDING WITH PORTRAITS OF THE AUTHOR'S
OWN BIRDS.
BY THE REV. FRANCIS SMITH.
CONTENTS.
A PLEA FOR THE CANARY
ORIGIN OF OUR OWN CANARIA
THE WILD CANARY
OUR LIZARDS
OUR YORKSHIRE SPANGLES
OUR NORWICH YELLOWS
OUR LONDON FANCY BIRDS
OUR BELGIANS
OUR GREEN BIRDS
OUR CINNAMONS
OUR TURNCRESTS
THE DOMINIE AND THE GERMANS
PREPARATIONS FOR BREEDING
NEST BOXES AND NESTS
OUR FIRST BIRDS
OUR MISFORTUNES
OUR INFIRMARY
ON CAGES
GROOMBRIDGE & SONS, 5, Paternoster Row, London.
Post 8vo, cloth gilt, with Woodcut Illustrations, price 5s.
THE ROSE BOOK A PRACTICAL TREATISE ON THE CULTURE OF THE ROSE.
COMPRISING
The Formation of the Rosarium; the Characters of Species and
Varieties; Modes of Propagating, Planting, Pruning, Training,
and Preparing for Exhibition; and the Management of Roses in all
Seasons.
BY SHIRLEY HIBBERD, F.R.H.S.
CONTENTS.
THE FAMILIES OF WILD ROSES
THE FAMILIES OF CULTIVATED ROSES
SUMMER ROSES
FORMING THE ROSARIUM
CULTURE OF ROSES IN THE OPEN GROUND
AUTUMN PLANTING
SPRING PLANTING
PRUNING, DISBUDDING, AND SEASONAL MANAGEMENT
CLIMBING ROSES
PILLAR ROSES
YELLOW ROSES
ROSES IN POTS
ROSES IN BEDS
ROSES IN GREAT TOWNS
TEA ROSES IN TOWNS
VARIOUS MODES OF PROPAGATING
SELECT LISTS OF ROSES
REMINDERS OF MONTHLY WORK IN ROSE GARDEN
HINTS TO BEGINNERS
GROOMBRIDGE & SONS, 5, Paternoster Row, London.
BOOKS FOR YOUNG NATURALISTS
Crown 8vo, elegantly bound, gilt edges, Illustrated with 16 beautifully
coloured Plates and numerous Wood Engravings, price 5s.
NESTS AND EGGS OF FAMILIAR BIRDS.
Described and Illustrated with an account of the Haunts and Habits of
the Feathered Architects, and their Times and Modes of Building.
BY H. G. ADAMS.
GROOMBRIDGE & SONS, 5, Paternoster Row, London.
Crown 8vo, elegantly bound, gilt edges, Illustrated with 8 beautifully
coloured Plates and numerous Wood Engravings, price 3s. 6d.
BEAUTIFUL BUTTERFLIES DESCRIBED AND ILLUSTRATED.
With an Introductory chapter, containing the History of a
Butterfly through all its Changes and Transformations. A
Description of its Structure in the Larva, Pupa, and Imago
states, with an Explanation of the scientific terms used by
Naturalists in reference thereto, with observations upon the
Poetical and other associations of the Insect.
BY H. G. ADAMS.
GROOMBRIDGE & SONS, 5, Paternoster Row, London.
Crown 8vo, elegantly bound, gilt edges, Illustrated with 8 beautifully
coloured Plates and numerous Wood Engravings, price 3s. 6d.
BEAUTIFUL SHELLS THEIR NATURE, STRUCTURE, AND USES FAMILIARLY EXPLAINED.
With Directions for Collecting, Clearing and Arranging them in the
Cabinet.
Descriptions of the most remarkable Species, and of the creatures
which inhabit them, and explanations of the meaning of their scientific
names, and of the terms used in Conchology.
BY H. G. ADAMS.
GROOMBRIDGE AND SONS, 5, Paternoster Row, London.
Crown 8vo, elegantly bound, gilt edges, Illustrated with 8 beautifully
coloured Plates and Wood Engravings, price 3s. 6d.
HUMMING BIRDS, DESCRIBED AND ILLUSTRATED.
With an introductory Sketch of their Structure, Plumage, Haunts, Habits,
etc.
BY H. G. ADAMS.
GROOMBRIDGE & SONS, 5, Paternoster Row, London.
NEW EDITION OF THE WORKS OF ANNA LISLE.
This elegant edition, large crown 8vo, is handsomely bound in cloth,
gilt edges, suitable for presentation, and Illustrated by the leading
artists of the day.
In One Volume, large crown 8vo, Illustrated, price 6s.
SELF AND SELF-SACRIFICE OR, NELLY'S STORY.
BY ANNA LISLE.
"A very beautiful story, with characters well drawn, scenery
vividly described, and interest admirably sustained. The
tendency of the volume is not only unexceptionable, but
excellent in a Christian point of view. We have seldom seen a
book in which the best and highest aim is so manifest without
the attractiveness of the tale being at all lessened by the
embodiment of religious principles."--_Eclectic Review._
"The story is so delightful, and the whole spirit of the book so
pure, that it compels our admiration."--_Daily News._
"Since 'Currer Bell' we have read nothing more genuine, nor more
touching. 'Nelly's Story' has power to carry the reader right
through with it, and can hardly fail to impress a moral of
inestimable importance."--_Carlisle Journal._
"Admirably written, pervaded throughout by fine, correct, and
wholesome sentiments."--_Morning Post._
"Its excellent moral tone, and keen observation, are sure to
render the book widely popular."--_John Bull._
"'Nelly's Story' is a good one. It is one of the best we have
read for a long time."--_Bucks Advertiser._
"Abounding in interest. We can hardly conceive a more suitable
gift-book."--_Lady's Newspaper._
"Will be welcomed, read, and talked about."--_Gentleman's
Magazine._
"'Nelly's Story' is told in such a good and pleasant way, and
withal is so useful and world-like, that we trust it may bring
to its authoress the fame that she is well able to
support."--_Tait's Magazine._
"We recognise and proclaim in the authoress of this thrilling
tale a quality beyond mere ability--genius of a very high order.
We claim for Anna Lisle a place amongst the most distinguished
writers of her age. The story is a brilliant effort of refined
and sanctified imagination throughout, quite as fascinating as
anything in the way of story, whether told by Scott, Stowe,
Dickens, or Currer Bell."--_Sentinel._
In One Volume, large crown 8vo, Illustrated, price 5s.
QUICKSANDS A TALE.
BY ANNA LISLE.
"It is a thoroughly woman's book. We can fairly say that we have
seldom met with a graver or more striking warning against the
consequences of over eagerness about worldly position and
advantages, more forcibly and, at the same time, gracefully
conveyed."--_Literary Gazette._
"Contains a great deal of quiet and powerful writing. Marty, the
maid of Mrs. Grey, might pass for a creation of Dickens. The
moral of 'Quicksands' is at once comprehensive and
striking."--_Weekly Mail._
GROOMBRIDGE & SONS, 5, Paternoster Row, London.
GIFT BOOKS FOR BOYS.
Foolscap 8vo, cloth gilt, Illustrated with 8 full-page Wood Engravings,
price 2s. 6d.
INVENTION AND DISCOVERY A COLLECTION OF INTERESTING ANECDOTES.
BY RALPH AND CHANDOS TEMPLE.
"Has a point and object, and a good one--nicely worked
out."--_Saturday Review._
"We can recommend this book as a Christmas present, and one
which has given us no small pleasure."--_Literary Churchman._
"Exceedingly well-timed. A volume which should be added to every
working-man's club in England."--Notes and Queries.
"Exhibits a conscientious regard for accuracy."--_Athenæum._
"The tendency is to instil the principle of self-help and the
advantage of earnest purpose."--_Bell's Messenger._
GROOMBRIDGE & SONS, 5, Paternoster Row, London.
Foolscap 8vo, cloth gilt, Illustrated with 8 full-page Wood Engravings,
price 2s. 6d.
ENTERPRISE AND ADVENTURE A COLLECTION OF INTERESTING ANECDOTES.
BY RALPH AND CHANDOS TEMPLE.
"Very handsomely got up. The 'Temple Anecdotes' will be one of
the most popular of Christmas books."--_Standard._
"A sensible, well-written book."--_Globe._
"We know of no work which will make a more acceptable present
than this extremely handsome and really useful book."--_Era._
"As a present for boys, nothing can be better."--_Daily News._
"The anecdotes are told with a clearness and simplicity that
cannot fail to give pleasure."--_Spectator._
GROOMBRIDGE & SONS, 5, Paternoster Row, London.
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