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Title: An Enquiry Into the Origin and Intimate Nature of Malaria
Author: Wilson, Thomas
Language: English
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*** Start of this LibraryBlog Digital Book "An Enquiry Into the Origin and Intimate Nature of Malaria" ***

Transcriber’s notes:

The text of this e-book has been preserved in its original form
apart from correction of a few typographic errors (omposition →
composition, recal → recall, gives → give, bloodvessels → blood
vessels), and insertion of some missing quotation marks. Inconsistent
hyphenation and inconsistent spelling (Scheld/Scheldt/Sheldt)
has not been altered. Footnotes have been numbered and positioned below
the relevant paragraphs.

                              AN ENQUIRY

                               INTO THE



                           By THOMAS WILSON,

                      HENRY RENSHAW, 356, STRAND.

                            COVENT GARDEN.





I have taken the liberty of dedicating this little work to you.
It treats of a subject on which I have made many experiments and
collected many observations in Belgium and in Holland. I have carefully
weighed the conflicting evidence of some distinguished observers, and
the conclusion arrived at is, that this conflict has arisen partly
from a want of due care in making the observations, partly from the
extreme difficulty accompanying all inquiries in which physiology and
pathology, health and disease, are necessarily involved.

In the course of my memoir I have endeavoured to do justice to
Holland, esteeming it to be the most remarkable country in the
world. I cannot find in the history of any other nation proofs so
clear of the beneficial effects of indomitable industry, directed by
intelligence, over the welfare and destinies of a people; nowhere do
I find evidence so convincing of the great results flowing from the
application of practical science to the wants of a people; nowhere do
I find to the same extent a sound commercial and political economy,
first developed and acted on in Holland, lead so directly to the
civilization and welfare of a nation. Those great principles which
other nations and other races discussed theoretically and elaborated
into systems, the nation of which you are a distinguished citizen,
discovered, adopted, applied, and enforced. To Holland, as a nation,
belongs eminently the character of practical. Whilst other nations left
uncultivated as they found them, or rendered unproductive, the most
fertile territories, seemingly unable to turn them to account, the
country and people to which you belong compelled the ocean to retire
from a barren, unprofitable, and untillable soil, which they converted
into a garden; and if ever the great problem of rendering the whole
earth habitable for man be solved, I may venture to predict--with
all due respect for other nations and other races--that the solution
must come from Holland. As it would be presumptuous in me--a humble
individual--directly to address a nation, I have ventured to do so
indirectly through you. Permit me, therefore, to dedicate this little
work to you, as the expression of my personal regard and friendship,
and of my deep respect for the nation to which you belong.

  I am, SIR,

      Most respectfully yours,

          THE AUTHOR.



  Epidemics--Their mysterious character--Distinction between endemics
  and epidemics--Malaria, where chiefly met with--Is it of one kind
  or several?--Author’s long residence in a _malaria_-producing
  country                                                       pp. 1–3


  The question as to there being several kinds of malaria, further
  examined--Theory of Macculloch, tracing to a malaria, chiefly
  generated by man himself, all forms of disease, from the plague to
  a common neuralgia--This theory now accepted, and to a certain
  extent acted on by the British Government--Experiments of the
  Board of Health--Results to be seen at Luton, Birmingham, and
  London                                                       pp. 4, 5


  The history of epidemics adverse to the theory of Macculloch--Results
  of confounding drains with sewers, and of converting drains into
  drain-sewers--Influence of the external world (earth, air, and water)
  over man, first examined by Hippocrates in his celebrated treatise,
  “_De aere, aquis et locis_,”[1] but with other views--Influence of
  modern chemistry over physiology--Men now expect from chemistry a
  solution of some of the great problems of physiology and pathology
  still unsolved                                               pp. 6–14

  [1] Περι αερον, ὑδατων καὶ τοπων. Cary’s edition. Paris. 1806.


  The great plague in the time of Justinian--View as to its African
  origin, and strictly contagious nature, adopted by Gibbon--Admits,
  however, the necessity for an insalubrious condition of the atmosphere,
  in addition to the presence of the poison--Its reappearance at present
  in Northern Africa (Bengazzi)--Modern theories as to its origin and
  mode of propagation, refuted by the histories of plague, cholera, and
  typhus--Murrains                                            pp. 15–25


  View of nature acted on by the Hollander and Brabanter--Their struggle
  to overcome the difficulties of their position--Rise of the Dutch
  Republic, and of the School of Mechanical and Practical Science of
  Holland--Its influence over Europe and the world--Drainage of the Lake
  of Haarlem--Practical instances of the truth of the principle, that
  “when man interferes with nature, he must carry through the work to an
  issue”--How to convert a peat-bog into a healthy meadow, a dreary waste
  into a profitable, cheerful farm                            pp. 26–30


  Sources of malaria--Various medical hypotheses refuted by Colonel
  Tulloch--Intermittents and remittents as they appear on the Western
  Coast of Africa and in Canada                               pp. 31–43


  Extent of life on the globe as proved by the microscope--Theory of
  Cuvier as to the nutrition of plants and animals--Vast extent of
  the microscopic living world--The “blooming of plants”--Results of
  disturbing the muddy banks of rivers--Sources of the bad odours of
  certain marshes and rivers--Remarkable influence of a change in
  temperature over the products of fermentation--Parasite theory of
  putrefaction, fermentation, and disease, refuted by Liebig, pp. 44–54


  Decomposition and metamorphosis of animal beings--Influence they
  exercise over the soil as a habitation for man--Disposal of the
  excreta and remains of animals and vegetables--Danger of these when
  accumulated--Immunity of savage tribes--Scurvy amongst the white
  troops at the Cape of Good Hope, the healthiest climate in the
  world--Metamorphoses of organic remains--Influence of oxygen, of
  nitrogen, and ammonia--Source of the inorganic principles--Fluate of
  lime in fossil bones--Danger to man of putrescent sea-water--Man’s
  incessant struggle with nature--Fatality of the climate of Rio
                                                              pp. 55–65


  Earth, air, and water, in relation to man--How modified by
  him--Results of that modification--Action and reaction--Antagonism
  of man to nature--Effects of human labour on the soil--How man
  protects his dwelling--Distinction between a drain and a sewer, a
  distinction first practically denied in England--Chemical elements
  of animal bodies--Nourishment of plants--Exhaustion of the soil in
  Virginia--Value of farm-yard manure--Agriculture in China--Effects of
  clearing the primæval forests of America--Causes of the hay-fever,
  typhus and typhoid fevers--Effects of bad ventilation--Importance
  of the infusoria in nature’s great scheme--Origin and action
  of _humus_--Functions of the _humus_ and of the leaves--Means
  adopted in Holland for the conversion of a bog or morass into a
  polder--Antediluvian vegetation--Elements which require being restored
  to the soil--Belgian agriculturists--Statistics of Quetelet pp. 66–88


  On poisons, miasms, and contagions--Difficulties besetting the
  questions as to their essential nature and origin--Poison of typhus,
  of yellow fever, and of the remittent fevers of hot countries--Their
  appearance at uncertain and distant periods in an aggravated
  form--Statistics of the recurrence of remittents in the West
  Indies--Light thrown by chemistry on the subject--Fermentation and
  putrefaction--Peculiar poisons--Distinction between a miasm and a
  contagion--Odour perceptible in sick chambers--Ozone,       pp. 89–98


  On the servitude of rivers--Practical knowledge of the ancients--Early
  Roman history a fable--The great social problems of _race_ and
  _climate_ in some measure unknown to the Romans--First mooted in the
  reign of Justinian--Present phases of human society--How affected by
  these two problems--Influence of civilization over the earth
                                                             pp. 99–110


  Author’s theory of malaria--Has malaria a real existence?--Action of
  ferments on the blood--A malarious air not dislodged by storms--Quality
  of the air over ditches, &c.--Experiments by the Author on microscopic
  mollusca--Influence of chemistry over physiology--Ammonia--Its
  volatility and universal prevalence in the air--Its sources and action
  on living bodies--Danger of drainage-works during summer--Spread
  of plants through the air--Appearance of strange plants in a
  country--Conclusion--Various phases of sanitary science--laws of
  decomposition and composition--Results to man of a false position in
  nature                                                    pp. 111–128

  APPENDIX                                                  pp. 129–136


  Page 98, line 2 (note), _should read_ “Hydrogen is the lightest known
  substance; its specific gravity is to that of air 732 to 10,000.”







In addition to the wide-spread desolating epidemics which appear from
time to time, mysterious in their origin, progress, and cessation
or disappearance--such, for example, as the plague of Athens, the
plague of London in the time of Charles the Second of happy memory,
the Indian or Asiatic cholera of modern times, and the disease called
influenza, a frequent visitor to Western Europe during the last
half-century--there exist localities unceasingly under the influence
of a poison inimical to human life. This poison, since it may be so
called, is known to haunt the deltas of large rivers, and seems to be
always present there; but it is found also, if we may determine its
identity by the identity of its deleterious influence on men, in other
and very various localities: sometimes it shows itself--and this most
commonly--in marshy and fenny countries, where no large rivers exist,
at other times by the banks of fresh-water lakes; now it haunts the
forest, and now the open plain, where marsh and fen, swamp and decaying
vegetation, seem all but absent. As the inhabitants of such localities
are especially afflicted with the fevers called intermittent and
remittent, it is the most natural thing in the world to ascribe to the
locality itself the origin of these diseases. When, however, we attempt
to generalize and assign to the same cause in a more concentrated form
those terrible fevers which render tropical countries the graves of
Europeans, great difficulties arise, and numerous objections, which the
best of statisticians, not to mention the simply medical observer, have
failed to elucidate and remove. Thus physicians are not agreed as to
the identity of the poison under all circumstances, or in other words,
demonstrative evidence is still wanting to prove that the cause of
fever on the western coasts of Africa is identical with that which has
so often in the Antilles destroyed England’s chosen troops, decimated
her fleets, crippled her power, annihilated her army, as at Walcheren,
and broken up the health of many a sturdy yeoman by the banks of the
Scheldt, of the Thames and its tributaries.

To this poison the term malaria has been applied--a word borrowed
from the Italian. This malaria is presumed, whatever it may be, to be
the cause (though not exclusively), on evidence almost amounting to a
certainty, of the fevers marked by intermissions and remissions; it
may also be the cause of the more terrible febrile diseases called the
yellow fever, the black vomit, &c., of tropical countries. On this I do
not insist. As regards intermitting and remitting febrile affections,
we are all but certain that to such localities as I have just alluded
to, their origin may be traced, however they may originate elsewhere.
A long residence in Holland and Belgium (countries supposed by many to
be in an especial manner the hot-bed and active parent of malaria)
has enabled me to observe, I trust in an unprejudiced manner, some
facts which may have escaped the observation of others. Long resident
in that land, on which perished miserably the best equipped army (an
army composed of veterans) which ever, perhaps, quitted England for
foreign aggression; in that land on which perished the chosen garrisons
of the mighty Napoleon; on that spot where they dragged on a miserable
existence, or perished in the prime of life; the writer of this
essay enjoyed the best of health. Even admitting the full influence
of a vigorous constitution, and an innate vitality equal to the
neutralization of all malaria, a something must still be ascribed to
observation leading him to avoid the hurtful and insalubrious agencies
at work around him--agencies ever active, ever seeking to destroy. This
information the author has thought might be useful to others, and with
this view he submits it to the public.[2]

  [2] Medical authors of the highest repute are exceedingly vague in
  their ideas respecting the nature of malaria; nor will it ever be
  otherwise until the question be taken up by the strictly scientific.
  Thus, Sir John Forbes says, in his “Holiday:”--“As the unknown
  thing which we term malaria or miasma of marshes, under certain
  circumstances gives rise at one time to simple ague, at another
  to a fatal remittent fever, &c.; and produces at times a morbid
  enlargement of the spleen, at others diseases of the liver, &c.; so I
  can imagine that some other _malaria_, or unknown thing or influence
  of local origin, may be the cause of ordinary bronchocele, of goitre
  of the Alps, and also of cretinism.”

  From the 1st of August to December the author hunted and waded
  through the marshes of Belgium and Holland in quest of water-fowl;
  his impunity from fever may be in part ascribed to a hardy training
  in early life.



Thus stood the question of malaria towards the close of the last
century, and for some years afterwards; its existence in certain
localities was never questioned--no one pretended to say that the fens
of Lincolnshire and of Cambridgeshire, the lowlands of Essex and Kent,
the muddy shores of the Scheldt and the Lower Rhine, the delta through
which the rapid Rhone finds its way to the Mediterranean, were healthy
countries. No one questioned the presence of malaria there, or its
power to inflict the plague of intermittent or remittent fever on most
strangers and on not a few natives who happened, unfortunately for
themselves, to be susceptible of its influence. The poison gave to the
Pontine Marshes a world-wide celebrity.

Again, of the more terrible febrile diseases of tropical climates, it
was suspected by many and boldly asserted by most medical men, that
to a malaria identical with that of Europe, but more concentrated by
high temperature, they owed their origin. Yet no one up to the period
I allude to--no physician, at least--had ascribed to neglected drains,
ill-conditioned sewers, imperfectly trapped cesspools, overflowing
dead-wells, &c., the origin of a malaria much more destructive than the
celebrated malaria of fenny or marshy countries, the malaria, if such
it really be, equal to the production of that plague, never absent, at
times most destructive--the dreadful typhus[3] of Western Europe.

  [3] Typhus, now subdivided into two--namely, the true typhus and
  typhoid fever.

At last one man, a shrewd, intelligent, and influential observer, a
man of genius, gave to the whole question a new phasis. Since his day
his hypothesis (for we shall presently find that as yet it deserves
no better name) has undergone a variety of modifications, as was to
be expected, in no way, however, affecting the practical deductions
originally drawn from it by its author. A brief history of this curious
episode in medicine, honoured by some with the pompous title of “a
revolution in sanitary science,” will fitly precede the inquiry on
which I am about to enter. Like the small white cloud warning the
navigator of the approaching tornado, this hypothesis, from its first
appearance as a humble essay in a monthly journal, has repeatedly
assumed, by force of circumstances, gigantic dimensions. Of it, as
of Rumour, it may be truly said, _Vires acquirit eundo_: it gathers
strength from motion. As is usual in England, a machinery has been
tacked to it of a character most heterogeneous, but withal so heavy
as already to threaten to surpass endurance--of the truth of which
remark no further evidence need be adduced than the modest demand of
six millions sterling to depurate or cleanse the Thames of those very
materials which, as a first experiment, and by no means an unprofitable
one, the Sanitary Board ordered and compelled the inhabitants of London
to throw into it. A brief history of this remarkable phasis of sanitary
science, as it is called, may prove acceptable to my readers.



About thirty years ago, as I have already remarked, one of the most
distinguished practical geologists of this or any other country
directed his attention to a subject of much greater difficulty than the
classification of rocks, and their subdivision into primary, secondary,
volcanic, and transition. His object was to discover the origin
or cause of those fatal diseases which, under the names of fever,
dysentery, plague, rheumatism, &c., render the position of man on the
globe so precarious, his life at times so brief, valueless to himself
or to others, his prospects so gloomy; in brief, by tracing to its
origin, if possible, the active agent of such woes to man, to destroy
its fatal influence by practical hygienic measures. In a word, Dr.
Macculloch hoped, by discovering the cause, to devise the means either
of effectually destroying malaria--using the term, however, in a sense
at that time peculiar to himself--or so to mitigate its effects as to
render it less destructive to mankind.

He, an acute and original observer, statistician, and scientific
man, properly so called, did not require to be instructed as to the
lamentable results which the premature death of millions causes to the
surviving relatives--results so eloquently and so correctly depicted
by the illustrious Quetelet in his work on Man.[4] Of all this he was
well aware, and a consciousness of such a condition of humanity, and
a firm belief in the opinion that the cause lay in some defect in our
social system, remediable by human means, led to those inquiries on
which the late Dr. Macculloch based his theory of a universal malaria
the cause of most diseases--a theory now adopted in its entirety by a
large section of the medical faculty, and by the English Government of
the present date.

  [4] Quetelet, “Sur l’Homme.”

The theory or theories of Macculloch,[5] as expounded by himself,
amounted in fact to this--that a poison, which may be called malaria,
is generated by vegetable and animal substances whilst undergoing
decomposition or putrefaction, and that to the presence of this poison
may be traced most of the diseases afflicting civilized man. In a
neglected drain or sewer he saw the cause of typhus, of agues, of skin
disease, neuralgias, &c.

  [5] The late Dr. Macculloch was a distinguished geologist in the
  employment of Government, representing in himself the department
  which has now swelled out into the Metropolitan School of Practical
  Geology, the Museum of Practical Geology, Jermyn-street, the
  geological department in connexion with the Ordnance, &c. &c. He
  resided mostly in London, and moved in the best circles. Though a
  strictly scientific man, he was a professor also of the conjectural
  art, having been educated as a medical man. Soon after publishing his
  first essays on malaria, thrown out as feelers to the profession and
  the public, he had his misgivings as to the safety of the course he
  was pursuing. To denounce open sewers, undrained streets, untrapped
  cesspools, and overflowing dead-wells, was clearly an attack on
  the proprietors of London houses; and he called one morning in
  great haste on a distinguished barrister, to consult him as to the
  possibility of a passage in one of his essays being construed into
  a ground for an action for libel! How changed now are the views of
  society in respect of all such matters.

These views of Macculloch respecting the origin of malaria and its
effects on man, were, when first published, and indeed for many
years afterwards, looked on with suspicion by the physicians of that
day; they were viewed, in truth, as wildly speculative, and wholly
unsupported by facts. This opinion still prevails with many, but they
are being rapidly borne down by a host of writers--many, it must not
be overlooked, enjoying lucrative official appointments, and who thus
have a deep and touching interest in supporting and maintaining the
theories of Macculloch. An opportunity will occur in the course of
this work of tracing briefly the progress of the mania--for such, to
a certain extent, it speedily became--and of assigning the merit or
demerit of the movement to those to whom it may be due. Here it is only
necessary to allude to it as being in fact the source of all those
visionary and Utopian schemes for the entire renovation of the social
state of man, alternately advocated or deprecated by a press naturally
chiming in with the prevailing public feeling. At times the discussion
acquires an almost feverish character--as when, for example, during
the present summer, “the river” exhaled an odour more than usually
unpleasant; at times it cools down in the presence of a proposal to
expend many millions of the public money on some wild, untried scheme,
under the superintendence of the very men who deliberately, and despite
many warnings, reduced “the river” to its present sad condition--of
men who had not the candour or the honesty to admit that, proceeding
on the conjectures of Macculloch, they hazarded one of the coarsest
experiments ever devised on the health of millions.[6] These were
the men whose course of action the Registrar-General endeavoured to
palliate, on the plausible ground that, although they poisoned the
river, the doing so was much less injurious to the inhabitants of
London than to suffer the cesspools to continue any longer buried
in the earth, although for the most part hermetically sealed! Thus
were they permitted in open day to pollute the surface-drains of the
metropolis, converting them into sewers--to render the streets and
squares impassable--and finally to convert the river itself into a kind
of elongated cesspool! This, says the Registrar-General, is an evil
of less magnitude than the permitting the cesspools and dead-wells to
remain as they were until gradually and cautiously disposed of by other

  [6] See the admirable speech of Mr. Disraeli in his place in
  Parliament, on the condition of the Thames.

It were easy to show, were it worth while--1st. How the persons to whom
I here allude suffered to be withdrawn from the Thames nearly a half of
its natural waters before reaching London; 2nd. How next they converted
the healthy surface drains of London and of its environs into odious
sewers, ignoring the distinction between drain and sewer, a distinction
which the most ignorant of day labourers perfectly understands, and
heretofore had uniformly respected; 3rd. How they refused to suffer the
suicidal act to proceed gradually and slowly, whereby the river, out of
its own natural resources, might and would in time have accomplished
its own depuration, but as best suiting their ultimate views, issued
compulsory edicts on the inhabitants of this great city to empty into
the river, and almost at once, the accumulated _excreta_ of a quarter
of a century, such being at least the average age of the contents of
the cesspools. Thus was demanded of the river a depurative force at
the least twenty times greater than under another system would have
been required of it. Lastly, to complete a series of experiments
so injurious to the public, but so profitable to individuals, the
same party proposes further to deprive the stream of all aid in the
purification of its waters, by pouring into the German Ocean the
entirety of the water which the natural drainage of London, and the
valley in which it stands, contribute to it, together with one-half the
waters of the river itself, taken from it above the tide-way for the
supply of the capital.

Thus, by a series of manœuvres, transparent enough to those who
have carefully watched the movements for the last twenty years, its
inhabitants are now called on at their own expense to remedy the clumsy
experiments of those who occupy positions they could not fill in any
country but England.[7]

  [7] It is right to observe that the unpleasant odour from the Thames,
  which during the month of June and part of July of the present year
  so disturbed the olfactory nerves of the Londoners, ceased at once
  so soon as the Bill for the purification of the Thames passed both
  Houses of Parliament. What connexion this had with the causes of the
  odour, and how these odours were so opportunely called forth and so
  quietly dismissed, I leave to be conjectured by the thoughtful of
  all classes. At this moment--August, 1858--during the most intense
  heat, the river is as sweet and fresh as a mountain stream, and has
  continued so ever since. Some are disposed to ascribe the cessation
  of the odours (for the stream is not in any way purified) to the
  throwing of quick-lime into the lower sections of the principal
  sewers; but if a remedy so simple as this was to be found in such
  a process, why was it not employed in June and July? It is only
  the unobserving who are surprised at such things, and who have not
  happened to observe what follows the spreading of an ancient cesspool
  over the fields by the road-side, or pouring its contents into a
  comparatively small river. The Thames is a comparatively small river,
  and the effects of pouring into it, at a convenient and suitable time
  (the dog-days, Parliament sitting, &c.), the contents of half-a-dozen
  cesspools of fifty years’ standing, undiluted and at once, would
  most assuredly give rise to results such as took place in London in
  June and July. The plot was a very nasty one--it might easily have
  been traced and the plotters detected: the sewer-makers, under the
  direction, no doubt, of the various boards, were very active in
  various quarters; and, not to mention other places, the main street
  of Hackney, for instance, for nearly a whole day, was by such means
  rendered quite unbearable.

Four-and-twenty centuries ago, Hippocrates, the father of medicine,
gave to the world his celebrated treatise, _de aere, aquis et locis_
περι ὑδατων αερον και τοπων, having for its object an inquiry into the
influence of the external world on man’s physical structure and moral
nature. To trace the origin of disease to these circumstances, does not
seem to have fallen within the scope of his argument; accordingly,
it can scarcely be said that any author prior to Macculloch ever
considered this matter from a philosophical or physiological point of
view, a reason for which may be found, I think, in the absence of a
minutely accurate chemical analysis of natural and artificial products.
No Ehrenberg had taught mankind the wonders of the living microscopic
world of life; even the geology of Macculloch was much behind the
profound analyses of the present day. Sober thinking men had rejected
the bold speculations of Buffon as to the antiquity of life on the
globe, and the demonstrations of the immortal Cuvier were as yet but
partially admitted; whilst the theories of Lamark, respecting the vast
influence of life in the construction of the crust of the globe, had
been suffered quietly to fall into abeyance. Life was thought to be but
a recent acquisition by the earth; the Silurian and Cambrian systems of
fossils were either unknown or misunderstood. These fossils, at present
called “the first stages of this grand and long series of former
accumulations,” must, in the nature of things, yield their claims to
others which geology will no doubt soon discover, thus rendering more
than probable the theory that life and the globe are coeval.

Placed accidentally in a country usually considered as a focus or
centre of that malaria or influence, whatever it may be, which man,
correctly, perhaps, esteems as the source and cause of remittent and
intermittent fevers, I have thought it might prove a labour of some
utility to mankind to test the theoretical opinions to which I have
alluded, by an appeal to facts submitted to more refined analyses than
were known at the period of their promulgation. Time can only show in
how far the views I venture to substitute for those now in vogue fairly
represent the truth. A power of nature, invisible and impalpable,
harasses mankind, destroys armies,[8] desolates districts and
countries, slays adult man at the moment when his native land expects
from him a suitable return for all the labour, trouble, and expense
bestowed on him: to inquire into the nature of this poison is the
object, or at least the main object, of this work. If we would rightly
understand its essence and properties, it may be admitted that we
ought to study carefully in the first instance its manifestations and
effects; now these are tolerably well known. The most difficult part
of the inquiry remains, that is, the demonstration of the essential
nature of the poison or miasm giving rise to such disastrous results.
All modern science leads to the conclusion that malaria, whether it
originate in circumstances over which man has no control, despite
every hygienic effort, or emanate from a combination of circumstances
mainly caused by man himself, or be only effectual when it meets with
individuals living in contempt of common sanitary precautions, must, by
its material nature, be within the range of philosophical research. To
Schonbein, a distinguished chemist now alive, we owe the discovery of
ozone. Major Tulloch had already hinted at the doctrine that the cause
of the frightful mortality in tropical countries was to be looked for
in electrical conditions of the atmosphere, of whose nature we as yet
are ignorant.[9] Other discoveries in this direction are sure to follow
at no distant period. What so obscure a short time ago as electricity?
Now look at its position, at least, as a science of application! Life,
it is true, is the mystery of mysteries, equally so in its origin and
extinction; yet granting this to be a truth, and foreseeing in it all
the difficulties of every inquiry directed to elucidate its essential
nature, every reflecting mind must be struck with the remarkable
discoveries of modern times, all tending to show the close alliance
between the chemical and vital phenomena, an alliance wholly unknown to
the most gifted of antiquity. The modern world, right or wrong, looks
to chemistry for the solution of many great and important problems, the
most elevated of which unquestionably is the discovery of the causes
rendering certain wide-spread localities of this earth unfit for the
habitation of those at least who may not claim them as their natal
soil; of which they are not the aborigines.[10]

  [8] The Walcheren expedition.

  [9] Rapid changes in the barometric pressure of the atmosphere
  strongly affect some persons, but the _malaise_ caused does not seem
  to be of a permanent character. In the spring, in Britain, when
  north-easterly winds prevail, the amount of skin disease, rheumatism,
  neuralgia, &c., is sufficiently remarkable, and the blights they
  cause in plants is a fact known to all. In a work published by
  Mulder (“Water en Miht,” Amsterdam, p. 181), we find it mentioned
  that Van Swinden investigated the mutations of atmospheric pressure
  as a cause of sickness, and arrived at the conclusion that a low
  pressure was not the cause of sickness and fever. He remarked that
  although there had been many years in which much sickness prevailed,
  seemingly connected with hot and dry weather, the barometer had
  varied but little. Thus, at Haarlem, in the period between 1755 and
  1780, the maximum was 30·9, the minimum or lowest, 28·0. The summer
  of 1779 was extremely hot, and a fever epidemic appeared which
  continued for three years. It was ascribed to the draining of several
  polders. Several learned societies made reports on the subject of
  this fever, but they elicited no new facts. It was generally agreed
  that the deeper the mud and turf containing vegetable matter were
  under water, the less was the sickness resulting from the draining.
  A Mynheer Driessen called public attention to the circumstance that
  on the coasts of Holland there were many places where animal and
  vegetable matter had accumulated and was in a state of rottenness
  or fermentation; and in this state he suggested that being carried
  inland by strong westerly winds, it might give rise to sickness.
  It is remarkable, however, that both the influenza and cholera
  progressed against the prevailing westerly winds.

  [10] Men in a state of nature seem to resist malaria. Thus the
  natives of Newfoundland and of Canada generally, and indeed of all
  America, withstood readily the malaria of their native land, but
  perished when brought within the influence of European domesticity.
  We must allow, however, for the power of race. On the other hand,
  it seems almost certain that the old Roman armies withstood the
  influence of climate much more effectually than modern armies do.
  They lived generally in camps, which they themselves fortified. Of
  their sanitary regulations we know nothing, but of their camps we
  know that no English or French soldiers could possibly stand their
  ground for any length of time similarly encamped. A legion (about
  12,000 men) encamped on a space of 700 yards square; what became
  of the refuse of the camp, and how was it disposed of? No Crimean
  disasters ever happened to Cæsar; he could not afford to lose his
  veteran Legions as we lost the Guards.



A very few years ago it was the general opinion, even of the best
informed, that epidemic diseases originate in atmospheric influences
over which man has no control. A reservation seems, however, to have
been made in respect of the Oriental, or as some term it, the African,
plague, a malady the most frightful to which man is liable. Writers of
the highest order traced to a damp, hot, and stagnating air, generated
from the putrefaction of animal substances, and especially from the
swarms of locusts, not less destructive to mankind in their death than
in their lives, the fatal disease which depopulated the earth in the
time of Justinian and his successors. The disease was reported to have
first appeared in the neighbourhood of Pelusium, between the Serbonian
bog and the eastern channel of the Nile. Thence tracing a double path
it spread to the east, over Syria, Persia, and India, and penetrated
to the west, along the coast of Africa, and thence to the continent
of Europe. But in order to explain how it spread, it was necessary
to invent another theory and add it to the first; the disease once
generated, was said to spread by contagion. It is related in “The
Decline and Fall of the Roman Empire,”[11] that in the spring of the
second year (after its first appearance), Constantinople, during three
or four months, was visited by the pestilence. It did not reach the
capital of the empire at once, but travelled slowly and irregularly,
after the manner of modern cholera. In the admirable descriptions of
the immortal historian, we can trace all the symptoms of the true
Oriental plague, identical in its phenomena and effects with the
sufficiently numerous visitations which have since occurred, and with
that no doubt which, lately originating at Bengazzi, and spreading to
Tripoli, once more threatens the European family of nations. In a damp,
hot, stagnating air, observes the historian, who in his account follows
Procopius, this African fever is generated from the putrefaction of
animal substances, and especially from the swarms of locusts, “not
less destructive to mankind in their death than in their lives.” But
the ferment and putrefaction thus created scarcely accounts for the
origin of the disease, and its extension north-wards into the coldest
regions of Europe is inexplicable on such a hypothesis, though aided
by the modern hypothesis that its propagation is due simply to the
neglect of sanitary regulations, a theory now happily extended to all
zymotic diseases. Passing over the question as to the contagious nature
of plague, typhus, cholera, scarlatina, measles, a question still
undecided, and adhering simply to facts, we are assured by Procopius,
the fidelity of whose descriptions the great historian seems disposed
to vouch for, that the disease always spread “from the sea coast to
the inland country; the most sequestered islands and mountains were
successively visited; the places which had escaped the fury of its
first passage were alone exposed to the contagion of the ensuing year.
The winds might diffuse that subtle venom; but unless the atmosphere
be previously disposed for its reception, the plague would soon expire
in the cold and temperate climates of the earth. Such was the universal
corruption of the air, that the pestilence which burst forth in the
fifteenth of Justinian, was not checked or alleviated by any difference
of the seasons. In time, its first malignity was abated and dispersed;
the disease alternately languished and revived; but it was not till the
end of a calamitous period of fifty-two years that mankind recovered
their health, or the air resumed its pure and salubrious quality. No
facts have been preserved to sustain an account, or even a conjecture,
of the numbers that perished in this extraordinary mortality. I only
find that during three months, five, and at length ten thousand persons
died each day in Constantinople; that many cities of the East were left
vacant, and that in several districts of Italy the harvest and the
vintage withered on the ground. The triple scourge of war, pestilence,
and famine afflicted the subjects of Justinian; and his reign is
disgraced by a visible decrease of the human species, which has never
been repaired, in some of the fairest countries of the globe.”

  [11] Gibbon, vol. vii., p. 421, Milman’s edition.

The plague of the time of Justinian is known to us only through the
medium of the Greek and Roman writers. We know nothing as to how
it affected the remote East, or whether that portion of the earth
escaped. No record exists to prove or disprove the passage across the
Atlantic, in ancient times, of plagues and pestilences, such as we
know now overleap with ease that seemingly impassable barrier. The
history of cholera in its progress from the East, though drawn up by
skilful official writers, tells us as little of its real nature as
Procopius did of the plague. It resembles in some respects the history
of ancient Egypt, each discovery merely adding another enigma to the
already existing and unexplained. Its propagation by contagion is still
denied by the first of medical authorities, and yet it must be admitted
that it pursues in a mysterious manner the paths of commerce, as if
by the abuse of trade, plagues, which would otherwise become extinct
in the land of their origin, are diffused over the continents of the

  [12] The cholera, in so far as I know, has not as yet penetrated
  beyond the tropic into the southern hemisphere.

The propagation of the plague by contagion was, as we have already
seen, distinctly denied by Procopius, and in this opinion he seems,
as in modern times, to have been backed by a majority of the people.
The immortal historian of “The Decline and Fall” did not partake
of Procopius’ doubts. “Contagion,” he remarks, “is the inseparable
symptom of the plague, which, by mutual respiration, is transfused from
the infected persons to the lungs and stomach of those who approach
them. While the philosophers believe and tremble, it is singular that
the existence of a real danger should have been denied by a people
most prone to vain and imaginary terrors. Yet the fellow-citizens of
Procopius were satisfied, by some short and partial experience, that
the infection could not be gained by the closest conversation; and
this persuasion might support the assiduity of friends or physicians
in the care of the sick, whom inhuman prudence would have condemned to
solitude and despair. But the fatal security, like the predestination
of the Turks, must have aided the progress of the contagion; and those
salutary precautions to which Europe is indebted for her safety, were
unknown to the government of Justinian. No restraints were imposed on
the free and frequent intercourse of the Roman provinces. From Persia
to France the nations were mingled and infected by wars and emigration,
and the pestilential odour which lurks for years in a bale of cotton
was imported by the abuse of trade into the most distant regions.”[13]

  [13] In the _Times_ of to-day (September 8th), the contagious
  character of the plague is stoutly denied by one who seems to write
  from authority, or who at least is evidently well backed by a strong
  party. The writer is evidently one of the Commissioners who met in
  Paris some years ago to inquire into the working of the quarantine
  laws. I offer no opinion on the subject,--though “one-idea” men,
  they have a show of truth on their side, and especially in this,
  that they adopt the popular view of the subject when they deny the
  contagious nature of the plague. They boldly affirm that plague
  only spreads in places where sanitary regulations are despised--a
  consoling and useful theory, even if it were not true. They made
  the same assertions of cholera--their hypothesis proved sadly at
  fault. The pump-well water-drinking theory is the latest expression
  of medical theorists in respect of the origin of the cholera: there
  never was a greater delusion. It does not merit a refutation, and is
  quite unworthy the professors of even a conjectural art. That the
  symptoms of cholera strongly resemble the action of a violent poison
  taken into the stomach, is not to be questioned, and that water may
  have been the vehicle of such a poison is neither impossible nor
  even improbable. The iced-water drinking population of Paris, of
  Palermo, and of many Sicilian and Italian towns, suffered terribly
  from cholera. Nor does it spare the temperate Mahometan, upon whom
  cleanliness is enjoined as an article of his faith. Still, the wholly
  inexplicable facts in the spread of cholera (and the same may be said
  of plague, typhus, and yellow fever) are far too numerous to admit of
  any generalization. Whilst the cholera spared Birmingham--at the time
  neither properly drained nor sewered, it nearly depopulated Bilston,
  a healthy town situated only a few miles from Birmingham, hundreds in
  the meantime travelling between the two places every hour of the day.
  It swept off the inhabitants of one side of a street in Deptford,
  leaving those on the other side unscathed. All drank of the same
  waters. The theory merits no attention.

Thus has been bandied about from the earliest times to the present
day, the great question of the origin of the pestilential diseases,
and their contagious properties when once produced. The question still
remains unsettled, nor has the advent of the cholera in modern times
contributed in the slightest degree to bring the disputation to a
demonstrative issue.

Are they of terrestrial or atmospheric origin properly, or do both
contribute their share towards the production of pestilences? How
originated the cholera, and how does it spread? These questions may
still be asked, and when asked must remain unanswered. The share
ascribed to man in the production and propagation of this and similar
diseases is mainly the object of this inquiry, and to that I shall
adhere as much as possible.

Men, ever anxious to discover the causes of events, ascribed the origin
of the plague in the reign of Justinian to the putrefaction of locusts;
but the same event may and has happened without being productive of
similar results--without, indeed, causing any disease whatever, as if
the poison, though present, were ineffectual unless aided by other
circumstances at present unknown to man. Those who have seen cholera
only as it prevails on the rotten banks of the Ganges, ascribe its
origin to heat and putrefaction, its extension to the habits of a
densely-congregated people. They forget, or choose not to remember,
that it raged in the depth of winter in the cold regions of Russia and
of Scotland, in thinly-populated villages, in hamlets, and insulated
cottages, scattered over the elevated yet cultivated estates of noble
and wealthy proprietors.[14] Those who have studied the phenomena of
typhus only in the horrid slums of Glasgow, in the wynds and closes of
cold and bleak Edinburgh--from which it is never absent, occasionally
raging with something like the virulence of a plague--ascribe the
origin and extension of the disease to cold and hunger, to a deficiency
of animal food, and to a contempt for all sanitary arrangements; but
they do not choose to remember that a few years ago typhus in its
worst form appeared in the south-eastern angle of England, spreading
thence through the midland counties, deeply affecting the population of
hamlets and villages the salubrity of whose site was unquestioned. And
if negative evidence be held sufficient to refute Procopius’ theory of
the origin of the true plague, we have but to look into the pages of a
modern traveller, whose official position naturally adds to the value
of his testimony. Mr. Barrow, in describing a visitation of locusts to
the Cape of Good Hope, makes the following curious remark:--“Their last
departure was rather singular. All the full-grown insects were driven
into the sea by a tempestuous north-west wind, and were afterwards
cast upon the beach, where it is said they formed a bank of three or
four feet high, which extended from the mouth of the Bosjesman river
to that of the Becca, a distance of nearly fifty English miles; and
it is asserted that when this mass became putrid, and the wind was
at south-east, the stench was sensibly felt in several parts of the
Sneuwberg.” The distance over which the stench was felt must have been
at least a hundred miles, the range of the Sneuwbergen being at about
this distance from the coast.

  [14] It raged most severely in Scotland, in the remarkably healthy
  village of Prestonpans and Fisher-row; in the highest and healthiest
  parts of Edinburgh; amongst the peasantry and miners scattered over
  the high grounds of Midlothian, belonging to the Marquis of Lothian.
  These people lived comfortably in detached cottages amongst the

It is hardly necessary for me to observe, that no disease followed the
destruction and putrefaction of these locusts. The colony of South
Africa still continues free from plague and cholera, and many other
diseases afflicting the most favoured of European lands; consumption,
scrofula, and fever are all but unknown. I am not aware that the
inhabitants are in any way remarkable for their sanitary arrangements,
whilst of the Hottentots it may with truth be said, that they are at
once the healthiest and dirtiest people in the world.

Thus, after the lapse of many centuries, the great questions debated
in the time of Justinian--may we not rather say in the days of
Thucydides?--surge up again whenever a new plague appears on the earth.
The professors of “the conjectural art,” anxious to vindicate their
claim to activity, and to share in the laudations bestowed on the
superior intelligence of the present day, offer at present a highly
consolatory view, not only as to the origin of these diseases, but as
to their speedy suppression. They argue that, but for the neglect of
hygienic measures, such influences or poisons would either not arise,
or would pass on their course, leaving the nations unscathed. In the
meantime, it is prudent to recall to the recollection of those who
arrive rashly at conclusions such as these--who theorize on narrow
local ground--who are sanguine enough to look forward to the speedy
extinction of all zymotic diseases, that pestilential and destructive
epidemics are not confined to man; that, under the form of murrains,
they destroy the beasts of the field. In the murrain of 1747, it is
stated on authority that 30,000 cattle died in Cheshire in the course
of half a year. The marsh districts suffered most; and it has even
been conjectured that such epizootic diseases usually originate amidst
swamps and malarious districts; but of this we have no proofs. Even
the harvests to which man looks for sustenance are not spared--nor
the vine; the life-destroying principle, attacking these lower forms
of life, cannot well be traced to the neglect of hygienic measures on
the part of man, or of the animals or plants themselves; and yet in
the midst of these bogs and marshes which undeniably give origin to
some forms of fever, the buffalo, the ox, the camel, the elephant,
and the wild of all species, live and thrive. Thus the question of
the origin of disease is complicated _ab origine_; the origin of
typhus--that scourge and pest of the nations inhabiting the temperate
regions, more especially of Western Europe, and of the British Isles
in particular--is absolutely unknown. To affect to trace it to a foul
drain, an uncleansed sewer, an untrapped cesspool, a laystall, a
collection of neglected rubbish, is clearly against the evidence and
the daily experience of thousands; but all are agreed that in certain
fenny and marshy countries fevers prevail--intermittent in temperate,
remittent in ardent climes nearer the tropic; whilst within the tropics
the life of the European stranger can scarcely be valued at a week’s
purchase.[15] To this destructive influence, most commonly connected
with a marshy soil, the Italian first gave the name of malaria--a
useful appellation, universally accepted as implying no theory; and had
such fevers been found only in such localities, the inference must have
followed, that a something, open to the chemist to discover, emanating
or produced by these marshes, was solely and distinctly the cause of
all such fevers. But now a more careful and extended inquiry shows
that such fevers are not confined to those districts, but infest even
the hay-field, are not unfrequent in or near woods growing on soils
where marshes have ever been unknown; whilst as regards the more ardent
remittents of Eastern countries, the statistics of Major Tulloch have
all but destroyed the theory which would trace to marshes exclusively
the fevers which in such countries set all medical treatment and all
human precautions at defiance.[16]

  [15] This question, in so far as regards a military life, has been
  handled in a masterly manner by Major Tulloch.

  [16] In the expedition to St. Domingo, the English army forming the
  expedition landed 10,000 strong; they withdrew in five weeks, without
  striking a blow or seeing an enemy. Their numbers were reduced to
  1100. See “History of the Expedition to St. Domingo,” by Dr. Maclean.

This uncertainty of life from the effects of malaria must ever, I
think, remain whilst the true nature of the poison is unknown; and
it is with a view to discover, if possible, the circumstances under
which it originates, that I undertook this difficult inquiry. Long
resident in a country supposed to be an ague-producing land, I watched
with much interest the social condition of a sagacious, prudent, and
industrious race of men, who could thus, at one and the same time,
preserve their liberty and life from the hostile assaults of furious,
implacable tyrants from without, and of an insidious, invisible enemy
within, walking stealthily around the habitations of men, poisoning the
air of his house, his fields, and gardens. It was in Holland that a
French general, writing to the great Napoleon, and complaining of the
destruction of the garrisons by fever, received from him the only reply
which at the time the necessities of the mighty conqueror permitted
him to give--“_L’homme meurt partout_.” “Man dies everywhere,” was the
only answer, if answer it could be called, to a kind-hearted commander,
more touched by the calamity around him than by the exigencies of the

But how was it that whilst French and English soldiers perished so
unaccountably in the prime of life, the inhabitants of these countries
lived seemingly unaware of the pestilence walking around and amongst
them? This problem may, I think, be solved; and as not foreign to
the matter in hand, I may be permitted to glance at the character,
position, and social condition of a race and a nation so distinct from
all other branches of the great European family. My remarks will bear
mainly on the influence they exercise over the portion of the earth
they inhabit, and on the modifications which man’s industry, guided by
prudence and science, may imprint on “the earth, the air, and water”
of the territory which, under the circumstances I now describe, may
especially be called their own.



Necessity is the mother of invention. “Quis psittacum loqui docuit?
Venter: Magister artium.”[17] A constant struggle with Nature for
existence taught the Hollander and Brabanter a practical philosophy in
respect of the management of river mouths, tidal rivers, low levels,
freshwater and seawater floods, unmatched by any other nation. It
required the unceasing vigilance of the most experienced scientific
men to combat the adverse circumstances under which their country was
placed. An error of calculation laid waste a province; a breach in a
sea-wall let in upon the land not only the ocean, but famine, followed
by its sure accompaniment--fever, and a wide-spread mortality.

  [17] Persius, Sat. Napoleon expressed the same idea when he said,
  “The stomach governs Europe.”

In this land there was no room for experimental jobbery. To have
placed a linendraper at the head of the great hydraulic works on
which depended the salubrity and prosperity of Amsterdam or Rotterdam
would have roused the indignation of the country, and brought the
matter to a speedy issue. But it was not until the rise of the Dutch
Republic that there sprung up, as a natural result, a school of
philosophy--of natural philosophy, and of the sciences of observation
and application--hitherto unmatched, a parallel to which can only be
found in the era immediately preceding Alexander the Great. Freedom
of thought and action produced Muschenbroek and Leuwenhoek, De Ruyter
and Van Tromp: then flourished the Elzevir press, and Scaliger was
invited by the traders of Holland to pass his days in peace and plenty
with them, that his presence amongst them might throw a lustre on
their country. In this land flourished Camper and Boerhaave; Albinus
and Ruisch taught anatomy; Swammerdam discovered the globules of the
blood. In the meantime Tasman and Van Diemen explored the ocean,
immortalizing their names and their country by the grandeur of their
geographical discoveries. The views of the traders of this the most
celebrated of all republics, were universal, and included mankind: with
them originated sound political economy. The civilization, peculiarly
human, which overcomes all natural obstacles, reached its height in
this free land; security of life and property, equality before the
law, a contempt for all sinister hereditary influences, a respect
for the natural rights of man, and an appreciation of man’s innate
worth, uninfluenced by all extrinsic circumstances, characterized in
the Netherlands a period standing out in bold relief, and in striking
contrast with the history of all other European nations.[18] In this
forward movement Haarlem was conspicuous, proofs of which may be found
in the Transactions of the society established in that city. About
1771 there was offered a prize for an essay on the Waters of Holland,
as to the existence of any matters injurious to man or beast, and to
describe such, if existing. An unsuccessful candidate for the prize (M.
Vander Wild) advanced in his essay this remarkable principle--that the
sap of plants consists of living beings, in a liquid element.[19]

  [18] It has been asserted on good authority, and not contradicted,
  that the “Natural Theology” of the celebrated Paley is a mere
  translation of a Dutch work.

  [19] This principle, so fertile in ideas, will one day, no doubt, be
  fully elaborated and studied to its results. These living beings may
  prove to be the syphons of perfume and the messengers of colour.

As the nation was free to think and to express their thoughts, nothing
practical or useful escaped them: the question as to the influence
of the drainage of lakes on the health of the inhabitants was ably
discussed during the last century, more especially as to the result
of draining the lowlands of Biensten, de Wonner, &c. M. Ungo Waard
and others describe the sickness which took place on the drainage of
Bleewyksthe. In Haarlem, in 1779, the deaths exceeded those of the
previous year by 396; in Amsterdam, by 1727; in Groningen, by 752. The
previous summer had been hot and dry, offering another proof that the
vegetable humus thus exposed to the air, fermenting and rotting, was
the cause of the sickness and increased mortality. In this land there
was no room--no margin, to use a commercial phrase--for experiments on
the pockets and the health of its citizens; they were citizens, not
subjects--far-seeing men, who calculated everything _d’avance_. And now
the draining of the lake of Haarlem shows that the race has lost little
of its ancient spirit of enterprise and industry, of that applicative
invention to the wants of civilized man which gives to Holland and
to her colonies an aspect to which no other country bears any
resemblance. The poisoning of rivers and streams by any combination of
adventurers could never happen there, and the scenes we have witnessed
lately in England would be wholly unintelligible in Holland. It is
here that vast morasses, seemingly valueless, are being converted into
fertile meadows, by processes of which the natives of other countries
have not the slightest knowledge. In this land it is the law that,
before any one be permitted to convert a peat bog into a lake by the
abstraction of the peat, security is demanded of him as to his means
to drain the lake about to be formed, to embank the excavation, and to
convert it into a healthy fertile meadow; in England, on the contrary,
such cautious procedure is held in the most sovereign contempt, as
wholly unworthy that fine chivalrous character for pluck, daring, and
exciting enterprise and speculation which marks the free-born Briton.

“Break up the cesspools,” shout the interested, “the receptacles of the
filth of millions for a quarter of a century, and pour them at once
into the Thames.” “It will poison the river and the adjoining country
for a lengthened period,” suggests the prudent observer of passing
events. “Persevere,” exclaims the go-ahead party; “have we not proofs
in Macculloch that nearly all known diseases arise from the cesspools?
Leave the river to take care of itself.” What, in the mean time, is
the course of action of the Mayor and Corporation of the richest city
in the world? Fully occupied with the distribution of their revenues,
they abandon the river and interests of a vast metropolis to a host
of talented and needy adventurers, whose name is legion. The people
in Holland and Belgium think that the refuse and excreta of the
inhabitants of towns, villages, and single houses cannot be too soon
or too effectually buried under or incorporated with the soil; we, in
this country, act evidently from a belief that this refuse, the product
of civilization, cannot be too extensively spread abroad in the open
air, and accordingly a formidable and well-paid staff of more than
2000 persons is organized to carry out the delusion to its conclusion.
Luton, Birmingham, and London, afford hints as to what these delusions
may one day end in: that they will proceed in their course, I doubt
not, for, like Macbeth, they are so far involved, that it were safer
to proceed than to back out from their position. This could only have
happened in the land where the greatest of all railways does not pay
the proprietors one shilling of interest on the enormous capital
expended in its construction.

Located by the mouths of the Rhine and Scheld, the ancient Batavians
must early have commenced their struggle with nature. We have no
information from early history of how that struggle began; but one
thing is certain--it was of great antiquity, for in the Morini--the
last of men--Cæsar encountered no fever-stricken, wasted, dejected
people: they must already have discovered the existence of that hidden
enemy, malaria, and taken measures for at least a mitigation of the

  [20] For Note on this subject, see page 54.



§ 1. For all practical purposes, the fevers termed intermittent
and remittent may be held to have their origin in one cause. Thus,
whether on the marshy coasts of Essex and Kent, or the more dreadful
banks of the Gambia and Niger, it is not improbable that the fever
so destructive to European life is of one character--mild in Essex;
fatal in Sierra Leone. But the fact is not to be overlooked, that when
fever assumes an intermittent character, however it may conduce to the
inefficiency of the population, it does not greatly swell the bills of
mortality; on the other hand, the remittent form of fever constitutes
that grand and hitherto insurmountable obstacle which Nature seems to
have placed to the extension of the white man over the earth, excluding
him, seemingly for ever, from the tropical regions of the world.

A favourite theory with medical men was, that the evil influence which
causes fever, whether in Essex or on the Gambia, by the Scheld or the
Niger, was a certain miasma produced by marshes more or less remote
from human abodes; sometimes it was maintained that to produce the
miasma these marshes must be in a great measure dried up, or in the
process of being so; at other times an opposite opinion was held. These
hypotheses were refuted, or at least much shaken, by Major Tulloch,
in his invaluable “Statistical Report on the Sickness, Mortality, and
Invaliding among Troops on the Western Coast of Africa” (p. 26). “So
long as the fever continued to make its appearance during the rainy
season, excessive moisture was deemed one of the principal causes,
but that theory has been abandoned since it has, on three or four
occasions, appeared and raged with equal violence in the middle of
the dry season. If we attempt to connect it with temperature, the
range of the thermometer offers equally contradictory results, the
disease having originated and prevailed nearly as often when that
was at the minimum as when at the maximum. Variations in atmospheric
pressure afford no clue whatever to the solution of the difficulty, for
here, as in all tropical climates, the fluctuations of the barometer
are exceedingly slight. No definite connexion has ever been traced
between the prevalence of any particular wind and the outbreak of
the disease; the breeze blows over the same district in the healthy
as in the unhealthy season. Besides, it seems entirely to negative
the supposition that any of these can be more, perhaps, than mere
accessories, when we find, from 1830 to 1836, the colony of Sierra
Leone remarkably free from fever, without any perceptible change
in these respects. It does not appear that the composition of the
atmosphere during the prevalence of yellow fever in this command has
ever been examined, to ascertain if it differed from what has usually
been observed at periods comparatively healthy; but this test has been
applied without any satisfactory result in other countries. Unless some
light, therefore, can be thrown on the subject by a careful examination
of the electrical state of the atmosphere at such periods, there seems
little hope of the origin of this disease being ever distinctly traced
to any appreciable agency--a circumstance which, except as regards the
interests of science, is perhaps of less importance, since where the
cause is so exceedingly subtle it would, even if discovered, be in all
probability beyond human control.”[21]

  [21] “Statistical Report on the Sickness, Mortality, and Invaliding
  among the Troops in the West Indies.” Prepared from the Records of
  the Army Medical Department and War-Office Returns. London, 1838. It
  has been objected to these Reports that they embrace only one class
  of lives. But this does not diminish their value, for the lives they
  report on are presumed to be the selected lives of men in the prime
  of life.

In corroboration of the same views, amounting in fact to a rejection
of the favourite hypothesis of the professors of the healing
art--namely, that this fever originated in the miasma of marshes
near the station, this careful and honest observer, whose merits as
such have subsequently been fully tested in the celebrated Crimean
inquiry, makes this further remark:--“The hypothesis that this fever
originates from the miasma of marshes in the immediate vicinity of
the station, as elsewhere it has been supposed to do, is directly
opposed to the fact of the Isles de Loss, Acera, and the peninsula
of Sierra Leone itself, being so subject to it, though all are in a
certain degree remote from the operation of any such agency. If it
be referred to similar exhalations wafted to the distance of several
miles, how is its prevalence to be accounted for at Fernando Po, a
mountainous region, and bordering on a mainland still more so, and
where, so far as can be ascertained, no such agency is in operation?
Instances of disease having raged with the same violence on the rocky
Isles de Loss and the sandy wastes of Senegal, as in those parts of the
coasts where vegetation is most dense, preclude the likelihood of it
originating in a superabundance of that agency. In every description
of situation along the coast has this scourge of Europeans been
found to prevail. The low, swampy Gambia, the barren Isles de Loss,
the beautifully-diversified features of Sierra Leone, the open and
park-like territory around Acera, the lone, jungle-covered hills of
Cape Coast Castle, and the rugged, mountainous island of Fernando Po,
however different in aspect, have all exhibited the same remarkable
uniformity in giving birth to the disease.”

It may, indeed, be objected that the fevers of Western Africa differ
essentially from those traceable to the deltas of rivers, and to the
lowlands alternately inundated and exposed to a high temperature, of
more temperate climates; but I see no good reason in favour of such an
opinion. The tables of sickness and mortality distinctly state that
the fevers were intermittents and remittents, but mainly remittents,
and that continued or ardent fever was scarcely present; whilst in
Canada precisely the reverse is the case, intermittents prevailing to
a great extent, remittents being comparatively rare. It would seem,
however, that whether or not these fevers spring from a common cause,
the temperature of the locality greatly influences the character of the

It is impossible to deny the influence humidity has in engendering
malarious tendencies, but it is not necessary that the humidity be to
any great extent. Water is essential to life, it is essential also to
the production of fermentation, of putrefaction; the absolute desert,
as I have already remarked, is always healthy; so is the surface of
the great ocean, which although it abounds with life, never putrefies,
never exhales unpleasant odours. Countries, like some districts of
Southern Africa and of Australia, where it seldom rains, are the
healthiest countries in the world; there fevers of all types are nearly
unknown, and the sufferers from such coming from unhealthy climates,
recover speedily from the sad condition to which a residence in a
tropical country and frequent attacks of fever may have reduced them.
The Royal African Regiment, composed mainly of deserters, left the west
coast of Africa for the Cape of Good Hope in 1817; many of them were so
reduced in health as to be obviously unfit for service in any country
where fevers of an intermittent or remittent character prevailed.
Now, a residence on the frontiers of the colony of the Cape not only
cured these fevers, but seems also to have been equal to the removal
of those sequelæ of fever and dysentery which haunt those who have
greatly suffered from them, bringing them in the end to an untimely
grave. Nothing of the kind occurred in this remarkable country; all, or
nearly all, recovered, and the mortality and sickness of this shattered
corps, removed from Sierra Leone and the Gambia to the frontier
districts of the Cape of Good Hope, fell considerably below what it is
amongst the same class in Britain. These facts merit the attention of
all interested in the welfare of the army of Britain, an army exposed
more than any other to the effects of climate in all regions of the

  [22] The army of England is, and perhaps has at all times been, an
  aggressive army, maintained to intimidate foreign races and nations.
  It resembles in many of its main features the army of ancient

§ 2. The statistics I have just referred to may seem to some to shake
all modern theories of malaria that have ever yet been offered to the
public. I admit this to be the case; but I trust to be able to show
that in the remains of animal and vegetable life, elements collected
in the greatest abundance by the banks of rivers and lakes in marshy
countries, near shores alternately exposed and covered by the tide, and
especially in tidal rivers, but not exclusively in such localities, we
have the source of that poison whose terrible effects on human life
need not be enumerated here.

The result of Major Tulloch’s report in regard to the relative
prevalence at different stations in British America of remittent and
intermittent fevers, shows in a still stronger light the difficulty
of establishing any uniform connexion between the presence of marshy
ground and the existence of these febrile diseases, to which the
exhalations from it are supposed to give rise; but they do not
refute the view I take,[23] which is based on the researches of the
profoundest chemists. As it was formerly shown that in some of the
Ionian Islands, totally destitute of marsh and comparatively barren
of vegetation, more remittent and intermittent fevers have been under
treatment among the troops, than in others where these alleged sources
of disease existed in the greatest abundance; so in the present Report
we find it established, that yellow fever of the most aggravated form
has repeatedly made its appearance in Ireland Island in the Bermudas, a
rocky barren spot only a few hundred yards in breadth, “containing no
marsh, and with little or no vegetation except a few cedar trees.”

  [23] Report: Section, Mediterranean.

“Conversely, again, we find that these diseases prevail to a remarkable
extent along the banks of the lakes and the margin of the streams in
Upper Canada, while they are comparatively rare in similar situations
in the Lower Province; that among the troops at Fredericton, living on
the marshy banks of a river, surrounded by a dense vegetation, scarcely
a case of them is ever known; and that a similar exemption is enjoyed
even by those at Annapolis and Windsor in Nova Scotia, though quartered
at the _embouchure_ of rivers daily subject to extensive inundations,
and of which the banks, for the distance of several miles, exhibit that
combination of mud, marsh, and decayed vegetation which is generally
supposed a most prolific source of such diseases.

“When in subsequent reports we come to investigate the operation of
these diseases on the west coast of Africa and other colonies, we shall
be able to adduce still more satisfactory evidence on this subject;
in the meantime we have felt it our duty to place the preceding facts
in a prominent point of view, not for the purpose of establishing any
particular theory, but to show how inadequate in many instances is
the supposed influence of emanations from a marshy soil to account
for the origin of these diseases. All the evidence obtained seems
only to warrant the inference that a morbific agency of some kind
is occasionally present in the atmosphere, which, under certain
circumstances, gives rise to fevers of the remittent and intermittent
type; and that though the vicinity of marshy and swampy ground appears
to favour the development of that agency, it does not necessarily
prevail in such localities, nor are they by any means essential either
to its existence or operation.

“Notwithstanding the doubt in which this branch of the investigation
is still involved, we may venture, from the facts adduced in all the
reports hitherto submitted, also to draw the conclusion, that when
this morbific agency manifests itself in the epidemic form, its
influence is frequently confined to so limited a space as to afford a
fair prospect of securing the troops from its ravages by removing to a
short distance from the locality where it originated. The history of
the epidemic fevers at Gibraltar furnishes several remarkable instances
of this kind, and we have also shown that, both in the West Indies and
Ionian Islands, one station has frequently suffered to a great extent
from yellow fever, while others within the distance of a few miles have
been entirely exempt.

“In the epidemic cholera at Montreal and Halifax, which seems to have
been in this respect somewhat analogous in its operation, we have also
had occasion to remark the sudden cessation of the disease immediately
on the removal of the troops to a short distance.”[24]

  [24] It may be asked, Why not inquire into the statistics of fever
  in Essex? The truth is, that no such exist. The conjectures and
  recollections of civil practitioners are valueless.

The discordance prevailing between observers, equally honest, equally
intelligent, arises, no doubt, from this, that all the elements of
the problem to be solved are not yet discovered; nor could this be
expected until a refined chemistry had more fully developed the
relation between chemical and physiological phenomena. The very
essence of the affinities between the soil and vegetable and animal
life was a complete mystery until lately, whilst the relations of the
superambient atmosphere to the organic remains of what had ceased
to live, were wholly misunderstood. The cause of the potato blight,
which produced a famine in Ireland, is still a mystery; so also is
that of the vine. A disease very fatal to horses, called Paard-sick,
from its only attacking the horse, is endemic in some districts of
the Cape; that is, in the healthiest country in the world. The nature
of the Paard-sick has never been discovered. It spares the _wilde_ of
the horse genus--the quagga, zebra, &c.--but is fatal to the domestic
breed. Man’s interference, then, proves at times fatal to his protegée.
It is everywhere the same, unless his interference be guided by all the
lights which the highest reasoning powers, the shrewdest observation,
and oft-repeated experience can afford. The two Canadas are in an
especial manner the land of rivers, lakes, marshy forests, swampy
meadows, and a soil into which the plough never penetrated until the
white man appeared. As a natural result, it might be conjectured and
presumed that intermittents and remittents, under at least certain
of their forms, would be equally frequent and universally diffused.
Statistics prove it to be directly the reverse, Upper Canada being to
Lower Canada, in respect of these fevers, as 178 intermittents is to
26 remittents; whilst even of these 26 it is affirmed that the greater
number of them came from the Upper Province. To show that I do not
exaggerate this singular fact, I quote the remarkable statistics of
Major Tulloch.

“Taking the results of these ten years as the basis of our deductions,
then, the prevalence of intermittent fevers in Upper compared with
Lower Canada is as 178 to 26. It is necessary, however, to keep in
view that all the admissions (amounting only to 26) from intermittent
fever in Lower Canada did not originate there, by far the greater
proportion of them having occurred among soldiers who came from the
Upper Province while labouring under that disease, or who had acquired
a predisposition to it during a previous residence there. Indeed,
except at Isle aux Naix and the other small stations along the banks
of the Richelieu, fevers of the intermittent type are rarely indigenous
in Lower Canada; at Quebec they are said to be unknown, and at Montreal
nearly so.

“In Upper Canada these diseases prevail most among the troops stationed
along the course of the great lakes from Kingston to Amherstberg, they
are almost unknown at Penetanguishene and By Town. The settlers who
reside even at the distance of a few miles inland rarely suffer from
them; yet the districts enjoying this exemption are in many parts
covered with lakes, intersected by streams, and abound in marshy
ground, decayed vegetation, and all the other agencies to which the
origin of this type of fever is generally attributed. A reference to
the report on Nova Scotia and New Brunswick will also show that though
the same agencies exist to a similar extent at some of the stations in
that command, intermittent fevers are almost unknown.

“These diseases, too, are said to be comparatively rare wherever the
surface is covered with dense forests, even though the ground is wet
and marshy. The vicinity of lands recently cleared is most subject
to them, particularly meadows or open patches of the forest, which,
though denuded of trees, have not been brought under cultivation.
It would appear, too, that their prevalence is diminishing with the
progress of agricultural improvement; for it will be observed, on
reference to the Abstract of Diseases, No. III. of Appendix, that since
1831--a period during which this province has been rapidly advancing
in wealth and population, and many important changes have taken place
in the vicinity and stations occupied by the troops--intermittents
have become comparatively rare, the proportion attacked having been
scarcely one-tenth part so high as the average previous to that
period. Intermittents most frequently occur from July to September,
when a high temperature prevails; but they are also to be met with,
though more rarely, in spring, when that agency could only operate
in a trifling degree to induce them. Though a source of inefficiency
among the troops, they add but little to the mortality, as not one
case in a thousand proves fatal. A person who has been once attacked
is exceedingly apt to suffer from them again; but this susceptibility
is easily removed by change of residence to the northern parts of the
province, or to Lower Canada.

“In some years, fever also manifests itself along the borders of the
lakes in the remittent form, but not of so fatal a character as in the
West Indies or the Mediterranean; for only one case in sixteen is found
to have proved fatal among the troops.

“The febrile diseases of Upper Canada are by no means uniform in their
prevalence. Even in years when the degree of temperature, fall of
rain, or extent of vegetation have been much the same, the proportion
of cases, particularly of intermittents, is very different. A general
impression exists, that their prevalence is in some measure dependent
on the height of the waters in Lake Ontario, which attain their maximum
in June or July. If, from the quantity of snow or moisture in the
course of the year, this is found to be greater than usual, febrile
diseases are expected to abound, and the reverse if the maximum has
been under the average. As Lake Ontario is the reservoir into which all
the waters of Upper Canada are drained off before finding their way
to the ocean, this theory, if accurately substantiated, would tend to
show how far the origin of these diseases depended on moisture, and we
therefore instituted the following comparison between the height of
the waters in the lake, as measured at Kingston for a series of years,
and the prevalence of fever in Upper Canada during the same period:

  |                 |1818.|1819.|1820.|1821.|1822.|1823.|1824.|1825.|1826.|1827.|1828.|
  |Average height of|     |     |     |     |     |     |     |     |     |     |     |
  |lake in Kingston |     |     |     |     |     |     |     |     |     |     |     |
  |Harbour in each  | 14 9| 13 3| 12 3|11 11| 12 1| 13 5|13 11| 12 5|12 10| 14 3| 15 7|
  |year             |     |     |     |     |     |     |     |     |     |     |     |
  |(feet and inches)|     |     |     |     |     |     |     |     |     |     |     |
  |Cases of inter-  |     |     |     |     |     |     |     |     |     |     |     |
  |mittent fever    | 110 | 319 | 509 | 348 | 222 | 143 | 171 | 135 | 111 | 220 | 489 |
  |in Upper Canada  |     |     |     |     |     |     |     |     |     |     |     |
  |Cases of other   | 109 |  54 | 150 | 152 | 132 |  69 | 168 | 190 | 155 | 185 | 300 |
  |fevers           |     |     |     |     |     |     |     |     |     |     |     |

“Here we find that, though in the last of these years the maximum
height of water in the lake happened to correspond with the greatest
prevalence of fever, the latter can by no means be looked upon as a
consequence of, or in any way connected with, the former; since in
1818, when the water rose to within a few inches of the same level,
there was less fever than in any of the years under observation;
whereas in 1820 and 1821, when the waters of the lake appear to have
been at the minimum, there was more than in any of the years prior to

“This supposition seems to have originated in the circumstance of
fevers being generally most prevalent from June to October, which
happens to correspond with the period when the waters of the lake
are at the greatest height; but the wide sphere over which these
statistical investigations now extend, has enabled us to show that
febrile diseases always prevail most at that season of the year, even
in countries where no such cause is in operation to produce them;
consequently, the rise of the waters in the lakes can no more be
regarded as the cause of fever in America, than the cessation of the
trade winds about the same period can be deemed a satisfactory reason
for the appearance of that disease in the West Indies. Both are merely
coincidences which, by those who have not a sufficiently extensive
field of observation, are apt to be mistaken for causes.”

There arises out of all such inquiries one obvious deduction--viz.,
that the essential nature of malaria is altogether unknown; and that
unless we choose to remain contented with such vague hypotheses as
those of Macculloch, now adopted by the Medical Board of Health of
Great Britain,[25] other inquiries must be entered on. The assertion
is as easily made as its refutation is difficult, that typhus fever is
caused by a neglected drain or ditch; that scarlet fever, small-pox,
and cholera have for their origin the same cause; that if they do not
immediately produce the poison, they predispose the human frame for
its reception; and that as a necessary result, all such diseases,
and deaths resulting therefrom, and from zymotic forms of disease
generally, are preventible by human agency. Let us leave these Utopian
views to the clever pens skilled in the art of making that seem new
which is not new, and that seem true which is not true, and patiently
inquire into some of the many difficulties besetting all investigations
into Nature’s processes, and man’s interpretation of them.[26]

  [25] As by the Registrar-General: see his Reports.

  [26] The ancient Egyptians seem to me to have long ago settled this
  question, practically. On the subsidence of the Nile they, without a
  day’s delay, commenced agricultural operations; nothing was allowed
  to fall into rottenness or putrefaction.



§ 1. It has been often remarked, and with great truth, that the world
abounds with life. In the remains of that which had once lived, which
was at one period organic, the illustrious Cuvier and the great
school to which he belonged saw the materials of life, the food, in
fact, of that which exists; he held that between the inorganic and
organic worlds there was an impassable gulf, or in other words, an
inconvertibility or a metamorphosis, call it by what name you will.
This plausible theory, with many others, is now controverted by modern
chemists, who boldly assert that no organic atoms or molecules, as
such, can serve as food for a plant or an animal. But be this as it
may--for chemists admit that the incombustible constituents or the
salts of the blood, so essential to the nourishment or support of
animal life, must have passed through organic bodies[27]--one thing is
certain, that the extent of life on the globe can scarcely be imagined.
For first, as regards the vegetable kingdom, do we not observe how, as
spring and summer advance, the organic beings which during winter had
lain dormant at the bottom, or deeply entombed in the waters (I speak
not of those to be seen at all times on the surface of the earth),
rise to the surface, bringing with them countless myriads of the ova
of aquatic animals and of those which haunt the surface of the water?
Amongst these stand pre-eminent the infusoria or zoophytes; with these
the atmosphere also becomes loaded. They form, in fact, the substratum
of all animal life, constituting the food not only of animals somewhat
larger than themselves, but of many much larger, as the various species
of the cyprinus. Many valuable gregarious fishes, as the herring,
char, and the finer species of trout, live on entomostraca; they in
their turn become the food of larger and more voracious fishes. Even
the whale lives on food a portion of which is almost microscopic. Now,
withdraw the water by which all this life subsists, and putrescence, or
fermentation and decay, must be the result upon a mass of life of which
the amount may be faintly conjectured by the fact that 4,100,000,000
millions of infusoria may be found in a square inch. These insects,
when dead, are found in strata extending to some acres, and many of
the fossils thus discovered belong to species of genera now alive.
The principles of life were at least as active in what we call the
old world (though in reality the young world), as in the present; the
researches of Ehrenberg, repeated by many others, have placed these
opinions beyond dispute.

  [27] Liebig.

Now, it is by no means improbable--nay, it is almost certain--that many
species of these infusoria reside in the vapour of the atmosphere.

The Austrian physicians came to the conclusion that the Asiatic cholera
was of local or terrestrial origin; the facts mentioned above confirm
this view to a certain extent, by disproving the general epidemic laws
supposed to regulate the progress of cholera and of fever (in which
cholera usually terminates), and by showing that the disease sought
out, as it were, the inhabitants of certain districts favourable
for the production of the deleterious influences I am now about to
consider. When the epidemical influence was superadded to these, the
disease appeared; its independence of changes in temperature may have
been owing to other circumstances not yet investigated. Connected
with this evolution of vegetable life in spring and summer, and with
its effects on man, is what is called the blooming of plants. The
presence of stagnant waters and of foul ditches may be discovered even
at a distance by the odour of gases, especially of the sulphuretted
hydrogen, they emit. Now, oxygen decomposes this gas, and thus it is
not so dangerous as represented to live near waters impregnated with
it; but should mud or vegetable refuse be left exposed by the drying up
of the waters, this gas ascends wherever the decayed matter is renewed
or turned over. Venice, Amsterdam, and other great cities similarly
situated, are not unhealthy, although their canals abound with mud;
but so soon as the traffic ceases or becomes trifling, a mud odour
arises, originating in what the French call _epuration_ or _floraison
d’eau_. In every country where there are ponds, canals, or ditches,
this vegetable growth takes place so soon as the temperature of the
water reaches 60° Fahr. As the quickening of the plants extends from
above downwards, from the leaves and stalk towards the roots, these
expand, and the mud becomes loosened; the plants imbibe carbon and give
out oxygen, and this circulation contributes to the loosening and to
the rising of the mud along with the plant. I have witnessed several
square yards of mud raised in this way from the bottom of the waters.
It subsides, of course, in due time.

We have seen that the vital force has no influence upon the combination
of the simple elements, as such, into chemical compounds. “No element
of itself is capable of serving for the nutrition and development of
any part of an animal or vegetable organization;” the vital force by
its influence merely combines inferior groups of simple atoms into
atoms of a higher order.

How stands it with the decomposition of animal and vegetable bodies
when the influence of the vital and conservative power has been
withdrawn? Let us attend to what an illustrious chemist has said on
this subject:--“Universal experience teaches us, that all organized
beings after death suffer a change, in consequence of which their
bodies gradually vanish from the surface of the earth. The mightiest
tree, after it is cut down, disappears, with the exception, perhaps,
of the bark, when exposed to the action of the air for thirty or forty
years. Leaves, young twigs, the straw which is added to the soil, juicy
fruits, &c., disappear much more quickly. In a still much shorter time
animal matters lose their cohesion; they are dissipated in the air,
leaving only the mineral elements which they had derived from the
soil.” “This grand natural process of the dissolution of all compounds
formed in living organisms begins immediately after death, when the
manifold causes no longer act, under the influence of which they were
produced. The compounds formed in the bodies of animals and of plants
undergo in the air, with the aid of moisture, a series of changes, the
last of which are the conversion of their carbon into carbonic acid,
of the hydrogen into water, of their nitrogen into ammonia, of their
sulphur into sulphuric acid. Thus their elements resume the form in
which they can again serve as food for a new generation of plants and
animals. Those elements which had been derived from the atmosphere,
take the gaseous form, and return to the air; those which the earth
had yielded return to the soil. Death, followed by the dissolution of
the dead generation, is the source of life for a new one. The same
atom of carbon which is a constituent of a muscular fibre in the heart
of a man, assists to propel the blood through his frame, was perhaps
a constituent of the heart of one of his ancestors; and any atom of
nitrogen in our brain has perhaps been a part of the brain of an
Egyptian or of a negro. As the intellect of the men of this generation
draws the food required for its development and cultivation from the
products of the intellectual activity of former times, so may the
constituents or elements of the bodies of a former generation pass
into and become part of our own frames.” “The proximate cause of the
changes which occur in organized bodies after death, is the action of
the oxygen of the air on many of their constituents. This action only
takes place when water--that is, moisture--is present, and a certain
temperature is required for its production.”

Let us not, then, be surprised at the seemingly discordant results
arrived at, and at the contradictory observations which have been
made in the best faith possible, and with every regard to truth in
science. The circumstances which seemed to be identical are merely
analogous, but in point of fact are essentially distinct, as proved
by the results. Changes inappreciable by human sense and as yet by
philosophical instruments, may and no doubt do effect results, to man
seemingly contradictory, simply because he comprehends them not. As
chemical science makes progress, these differences are being reconciled
and understood. Thus, as mere temperature exercises a truly remarkable
influence over the nature of the products of fermentation, may it not
be the efficient cause of the difference we observe between the malaria
of the delta of the Mississippi and that floating near the muddy banks
of the Scheldt? The juice of carrots, beet-root, or onions, which is
rich in sugar, when allowed to ferment at ordinary temperature yields
the same products as grape-sugar, but at a higher temperature the whole
decomposition is changed--there is a much less evolution of gas, and no
alcohol is formed.

In the fermented liquor there is no longer any sugar, and thus may it
be in the great laboratory of nature; the product of the fermentation
will assume in one locality a character it does not possess in another.
The elements are the same; there is merely a change in temperature.

Are there facts to prove that certain states of transformation or
putrefaction in a substance, are likewise propagated to parts or
constituents of the living animal body? Such facts exist. On no other
principle but that of assimilation can we explain the phenomena of
poisoning by the puncture of the living hand in dissecting-rooms, the
instrument being impregnated with a fermentescible and putrefactive
substance, there undergoing a decomposition. Similar, unquestionably,
must be the action of animal poisons, such as that of poisonous
substances, whether animal or vegetable, of the poisons giving rise
to zymotic diseases, &c.; and such may be the origin of the fevers
caused by the unknown principle which must still be connected with
the decomposition of organic bodies most frequently found in marshy
countries. But before entering more fully on this important matter,
I shall first weigh the evidence for and against a theory long
fashionable, and which may even now have its supporters--namely,
whether fermentation or the revolution of higher or more complex
organic vegetable into less complex compounds, be the effect of the
vital manifestations of vegetable matters, and whether putrefaction or
the same change in animal substances be determined by the development
or the presence of animal beings. They who maintain this theory, assume
as a natural consequence of the views that the origin of miasmatic or
contagious diseases, in so far as they may be referred to the presence
of putrefactive processes, must be ascribed to the same or to similar

§ 2. The refutation of this view by Liebig seems satisfactory, and has
not yet been satisfactorily replied to. The subject is one of much
interest; the theory has furnished a foundation for some unquestionably
entirely fallacious ideas concerning the essence of the vital processes
generally, of many pathological conditions, and the causes of certain

These persons regard fermentation, or the resolution of higher or
more complex organic vegetable atoms into less complex compounds,
as the effect of the vital manifestations of vegetable matters; and
putrefaction, or the same change in animal substances, as being
determined by the development or the presence of animal beings.
They assume as a natural consequence of this view, that the origin
of miasmatic or contagious diseases, in so far as referrible to the
presence of putrefactive processes, must be ascribed to the same or
similar causes.

The most obvious and important considerations in support of this view
of fermentation, are derived from observations made on the alcoholic
fermentation, and on the yeast of beer and of wine. The microscopic
researches of physiologists and botanists have demonstrated that beer
or wine yeast consists of single globules strung together, which
possess all the properties of living vegetable cells, and resemble very
closely certain of the lower family of plants, such as some fungi and

In fermenting vegetable juices, we observe, after a few days, small
points, which grow from within outwards; and these have a granular
nucleus, surrounded by a transparent envelope. The simultaneous
appearance of the yeast-cells and of the products of decomposition
of the sugar, is the chief argument in support of the opinion that
the fermentation of sugar is an effect caused by the vital process,
a result of the development, growth, and propagation of these low
vegetable structures. But if the development increase, and propagation
of these vegetable cells or tissues be the cause of fermentation, then
in every case where we observe this effect we must suppose that the
causes or conditions--namely, sugar, from which the cell-walls are
produced, and gluten, which yields their contents--are both present.

Now, the most remarkable fact among the phenomena of fermentation,
and that which must chiefly be kept in view in the explanation of the
process, is this, that the ready-formed cells, after being washed,
effect the conversion of pure cane-sugar into grape-sugar, and its
resolution into a volume of vapour and alcohol, and that the elements
of the sugar are obtained without any loss in these new forms; that
consequently, since three pounds of yeast, considered in the dry state,
decompose two hundred-weight of sugar, a very powerful action takes
place, without any notable consumption of matter for the vital purpose
of forming cells. If the property of exciting fermentation depended on
the development, propagation, and increase of yeast-cells, these cells
would be incapable of causing fermentation in pure solutions of sugar,
in which the other conditions necessary for the manifestation of the
vital properties, and especially the nitrogenous matters necessary for
the production of the contents of the cells, are absent.

Experiment has proved that in this case the yeast-cells cause
fermentation, not because they propagate their kind, but in consequence
of the decomposition of their nitrogenous contents, which are
resolved into ammonia and other products--that is, in consequence of
a decomposition which is exactly the opposite of an organic formative
process. The yeast, when brought into contact successively with the
new portions of sugar, loses by degrees entirely its power of causing
fermentation, and at last nothing is left in the liquid but its
non-nitrogenous envelopes or cell-walls.[28]

  [28] Liebig: Letters on Chemistry.

On the other hand, it may be admitted that fungi and agarics, and
all that lives, vegetable and animal, contaminate the air when dead;
they absorb oxygen and give out vapours of which some are clearly
detrimental to human life. The effect of breathing air so contaminated
is in some countries immediate--that is, the incubation of the poison
requires only a few days, in others many months. Waters in a state of
fermentation or putrefaction seem to poison the plants themselves, for
duckweed and other swimming plants die, and the swallow and the marten
disappear. On the wide ocean and over the absolute desert, the air is
always pure, nothing living is decomposing; but watch the mud coasts,
and observe the pestilential effects of sea water when suffered to
evaporate, or still more when confined to a locality and suffered to
decompose. In the ancient world, as in the modern, nature teemed with
life, since a cubic inch of the fossil infusoria, contains 41,000
millions of individuals. The microscopic shell fish called entomostraca
were equally abundant.

When the evaporation of sea water is quickened by an elevation of
temperature, as in the South of France, noxious and unpleasant
odours, injurious to vegetable life, are distinctly perceptible. The
putrescence and fermentation caused by heat acting on the remains of
life in sea water left to evaporate, as between Rio and Cape Frio, in
the Brazils, seem to be the cause of, or at least to give terrible
effect to, yellow fever.

Vegetable life is equally abundant, and it may be as injurious when
decomposing in its effects on human life. Lichens speedily cover the
walls of neglected houses, and cause sickness by their decomposition.
The spore or sporule, which in flowerless plants performs the office
of seeds, floats in the atmosphere, and seems to be the cause of
the hay-fever so frequent in fertile lowlands. Nor need we quote
the recent drainage of the Lake of Haarlem in proof of the sure
results of exposing masses of dead animal and vegetable substances
to putrefaction--namely, ague, various fevers, and other ailments
indicative of a poison or malaria affecting the general mass of the
blood. Of the minuteness of animal life, it is only necessary to remark
that we are acquainted with animals possessing teeth and organs of
motion, which are wholly invisible to the naked eye. Other animals
exist which, when measured, are found to be many thousand times
smaller, and which nevertheless possess the same apparatus. Their ova
must be many hundreds of times still smaller. It is to this invisible
world in all probability, and to its decomposition and putrefaction,
or at least to influences arising therefrom, that the essential cause
of ague, and other febrile diseases of an intermittent and remittent
character may be referred, aggravated, no doubt, by insalubrious
atmospheric constitutions of which we know nothing. These from time to
time affect and lower human vitality--a fact admitted by all physicians.

       *     *     *     *     *


  The special-pleaders who formed the Council of the late Board of
  Health argued that, “as there exists an obvious harmony between our
  physical and social constitutions, the necessity of intercourse
  between all the members of the human family is one of the final
  necessities of our race” (“Report on the Quarantine Laws,” Board of
  Health, p. 64); in other words, that “the diseases supposed to be
  contagious by our predecessors, _cannot be contagious_, because such
  a supposition is at variance with _a theory (of their own invention)_
  that there exists a necessity of intercourse between all the members
  of the human family;” and therefore all quarantine laws ought to be
  abolished. But are not small-pox, measles, scarlatina, hooping-cough
  contagious? And as regards “the necessity of intercourse between all
  the members of the human family,” were we to consult the Chinese,
  the Hindoo, the Peruvian, the Mexican, the Caffre, the Negro, the
  Turk, the Morocene, they would unhesitatingly tell you that such an
  intercourse is sure to end in their destruction. Under a Trajan or
  an Alexander, an Antonine, or even an Augustus, the world no doubt
  was benefited by an universal intercourse between all the members of
  the human family _then known_, and such an intercourse was highly
  beneficial to humanity; but the kind of intercourse established by
  the Clives and Pizarros is of a very different nature from that of
  Alexander and Trajan. Civilization is the direct result of artificial
  wants, the gratification of which can alone be met by a free and
  unrestricted commerce. By violence an empire may be overthrown,
  and by rapacity its inhabitants may be deprived, not only of their
  land and property, but even of their natural rights as men, as in
  India under the administration of England; but all these crusades
  have no reference whatever to an ameliorating of the condition of
  mankind; they simply form episodes in the history of the human
  race, respecting which historians take extremely different views.
  The conquests of Mexico and Peru and India form episodes in the
  respective histories of Spain and Britain by no means flattering to
  the character of these nations.



During life animal bodies undergo continual decomposition and
recomposition; life is in fact a perpetual metamorphosis. Whilst alive,
the products of vitality (_excreta_) are returned to or deposited in or
on the surface of the earth, and carried by drainage and other means
into the nearest water, river, or stream; we have lived to see them
thrown _en masse_ into a tidal river the waters of which serve at the
same time to furnish most of that required for the economy of a vast
capital and many surrounding towns; in the same country the cesspools
and dead-wells constructed to receive the liquid and solid _excreta_ of
dwelling-houses are not unfrequently constructed close to the pump-well
which is to supply the inhabitants with pure water for culinary

To these extraordinary facts I shall shortly return. They show the
extent to which intelligent, talented, shrewd men may suffer themselves
to be deluded and led aside from the path pointed out by common sense,
more especially when crotchets are substituted for principles; when
men fancy that in following out some imperfectly-observed inquiry,
they are imitating nature--that nature which is ever consonant with
herself, which created all animals, and which knows how to dispose of
their excreta when living, and of their remains when dead, without
detriment to the living. The Caffre, the Hottentot, the Bosjieman, the
North-American Indian, the Bedouin, require no sanitary arrangements,
no laws regulating, nor staff to carry out a code of theoretical
Utopian schemes, sure to revert on the heads of those foolish enough to
employ them; the excreta deposited on the earth disappear, so do also
the remains of animal life. We never hear of any pestilence, fever,
scurvy, dysentery, small-pox, hooping-cough, malignant sore-throat,
or other zymotics, originating amongst them. It would, indeed, almost
seem that such evils do actually owe their origin to human agency
and to human civilization; where civilized man makes his highest
endeavours, there his most signal failure occurs; experience teaches
him nothing; the insolence of wealth naturally leads to the contempt of
all knowledge derived from means otherwise than national and native.
In Britain the muddy banks of rivers, which in Holland and Belgium are
covered with vegetation, lie exposed, festering in the sun’s rays,
the fertile source of agues and other diseases; here they are being
continually exposed, or alternately covered with water, which is then
allowed to evaporate; this mud is not suffered to rest, but stirred
up in a variety of ways, as best suits the convenience of the parties
interested. It suits, for example, the proprietor of a long-neglected
drain or sewer, cesspool or filthy stagnant canal, or a common ditch,
which once was a clear rivulet, to cleanse it out. He selects the
warmest weather and the longest day for that special work, or he
spreads the contents of the cesspools of half a century’s collection on
the fields, suffering it to remain there for weeks, thus rendering the
roads all but impassable. The selected lives of the finest men in the
kingdom, petted, fed, clothed, and lodged at the public charge, without
anxiety or a care for to-morrow--the Guards of England--die under his
fostering hand, in the ratio of three to one of the care-worn and
toil-exhausted peasant, miserably fed, scantily clothed, badly lodged,
and full of anxiety for the morrow. Now, how comes this? Simply, I
believe, from this--that man, knowing much better than nature, has
chosen to take her place, to do her work clumsily, and to fancy that he
is doing it well; to interfere, and not to carry through the works he
has undertaken. What other proof can be required than the fact that, on
the frontiers of the Cape of Good Hope, in the healthiest country in
the world--a fact proved not only by the statistics of the celebrated
statistician, Major Tulloch, but by the evidence of all medical men who
have resided there,--where the mortality is not a half of what it is
amongst the most favoured counties of England--in such a country, where
every man might have had a mile square of ground to live on, military
arrangements contrived to break down whole regiments of the healthiest
young men England could produce.[29]

  [29] Report, p. 176.

The Dutch Boers and Hottentots were astonished, as well they might
be. “Towards the end of June, 1836,” observes Major Tulloch, “very
decided symptoms of scurvy began to manifest themselves among part of
the 75th Regiment at Fort Armstrong, and subsequently extended to most
of the other stations along the frontier. The total number of cases
reported either as scorbutus or purpura, were 134, of which 4 proved
fatal; the others readily yielded to change of air, with improved
diet and accommodation.” As was to be expected, the Hottentot troops,
on the same ground, being left to act generally in accordance with the
dictates of their own common sense, wholly escaped the disease.

Let us now briefly review the means adopted by nature for the disposal
of those remains so embarrassing to the civilized, so innocuous to
man living in a semi-barbarous or savage state, and which prove to
the former a source of infinite expense, discomfort, and disease. The
problem has reference to the soil, to the air, to the water; to the
condition of all three as regards the preservation of animal life
generally, man included.

I have already remarked in a preceding chapter, that all organized
beings after death undergo a change, in consequence of which their
bodies, as such, disappear from the surface of the earth. In a short
time after the event, animal matters lose their cohesion; they are
dissipated into the air, leaving only the mineral elements they had
derived from the soil. The change commences immediately after death:
with the aid of moisture and exposure to the air, the bodies of
animals, as well as plants, undergo changes, the last of which are[30]
the conversion of their carbonic acid and of their hydrogen into water,
of their nitrogen into ammonia, of their sulphur into sulphuric acid.
Thus, their elements assume or resume forms in which they can again
serve as food to a new generation of plants and animals. “The same atom
of carbon which, as the constituent of a muscular fibre in the heart
of a man, assists to propel the blood through his frame, was perhaps
a constituent of the heart of one of his ancestors, and any atom of
nitrogen in our brain has perhaps been a part of the brain of an
Egyptian or of a negro.

  [30] Liebig, 1851.

“As the intellect of the men of this generation draws the food
required for its development and cultivation from the products of the
intellectual activity of former times, so may the constituents or
elements of the bodies of a former generation pass into, and become
parts of, our own frames. The proximate cause of the changes which
occur in organized bodies after death is the action of the oxygen of
the air on many of their constituents. This action only takes place
when water--that is, moisture--is present, and requires a certain

The great agent in all these changes is oxygen, as has been already
sufficiently explained when speaking of the decomposition of vegetables
after death. I shall first attend to the influence these changes have
on the soil as producing agents, intended to restore to the soil those
vivifying powers which it never seems to lose when man interferes not;
and lastly, to consider briefly its influence on man himself.

The development of scarcely any plant can be imagined without the
assistance of nitrogen or of azotized materials. Now, under certain
conditions known to all botanists, this azote must come from rain
water, either in the form of atmospheric air, or under that of ammonia.
Chemists have, I think, proved that it originates in the ammonia
contained in the atmosphere, and not in the azote as it naturally
exists in the air. The problem is put and solved in this way by Liebig,
“Let us consider a farm suitably conducted, and of an extent sufficient
to maintain itself, ammonia exists there in a sufficient abundance in
rain water and snow; in the water of most fountains; it exists in the
air in abundance, and is being constantly renewed by the decomposition
of animal and vegetable bodies, and is restored to the soil by the
rain, and then absorbed by the roots of plants, and produces, according
to the organs, albumen, gluten, quinine, morphine, cyanogene, and a
great number of other crystallized combinations.”

The most decisive proof of the part played by ammonia in the
nourishment of plants is furnished us by the use of manure in the
cultivation of cereals and green forage. According to the distinguished
chemist so often quoted in this essay, animal manure (_fumier_) acts
solely by reason of its production of ammonia. The history of the
Peruvian guano, a substance so highly ammoniacal, proves all these
assertions; this celebrated manure, which fertilizes a soil (the
Peruvian) of the most remarkable sterility, consisting mainly of white
sand and argil, is composed chiefly of urates, urate of ammonia,
oxalate of ammonia, phosphate of ammonia, carbonate of ammonia, and
some other salts.

Thus did the ancient Peruvian, like the Chinese, stumble on the
solution of problems involving the fate of millions by simple
experience alone, wholly unaided by science, which steps in afterwards
and gives the _rationale_ of the process; teaches us that all wheats
do not equally abound in gluten; that rice is poor in azote; potatoes
equally so. Practical agriculturists still find difficulty in applying
with success the processes recommended by the chemist; but these, no
doubt, will gradually be overcome.

“Since we find azote[31] in all the lichens which grow on basaltic
rocks; that the fields produce more azote than is brought to them
in the shape of aliment; that we meet with azote in all soils
(_terrains_), even in minerals which happen never to come in contact
with organic matters; that in the atmosphere, in rain-water, and in
that of fountains or springs, in every description of soil we meet
with this azote under the form of ammonia, as a product of the slow
combustion or of the putrefaction of anterior generations; that the
production of azotized principles greatly increases in plants with the
quantity of ammonia presented to them in animal manure,--we may in
all safety conclude that _it is the ammonia of the atmosphere which
furnishes the azote to plants_.

  [31] Traité de Chimie Organique. Par M. J. Liebig. pp. 88.

“It results from the foregoing[32] that the carbonic acid, the ammonia,
and the water, include in their elements the conditions necessary
for the production of all the principles of living beings. These
three bodies are the ultimate products of the putrefaction and of the
_eremacausis_ (slow combustion) of all animal and vegetable races. All
the products of the vital force, so numerous and so varied--all after
death return to the primitive forms in which they first appeared or
from which they originally sprung. Death, the complete dissolution of a
generation, is always the source of a new generation.”

  [32] Liebig, _loc. cit._

Equally curious, but foreign to my present purpose, is the inquiry into
the sources of the inorganic principles in plants and animals. These
sources were inappreciable until a more refined chemistry appeared.
Sea-water contains only the 1/12,400th of its weight of carbonate
of lime, and yet this quantity suffices for the production of the
essential components of the shells of myriads of crustaceans and
corals. Whilst the atmosphere contains but 4/10,000ths to 6/10,000ths
of its volume of carbonic acid, the amount in sea water is more by a
hundred times, and yet in this medium we find another world of animal
and vegetable life, which finds re-united in the ammonia and carbonic
acid the same conditions which enable human beings on the surface of
the solid earth (_terra firma_) to live and to maintain their species.

It would even seem that the essential constituents of some organs have
altered in the course of ages, without affecting, or being materially
affected by, the principles of life. Thus it would seem that fossil
bones contain the fluate (fluorure de calcium) of calcium in much
larger quantities than the bones of recent animals; and the same remark
has been made in respect of the composition of the crania of men found
at Pompeii. They resemble in this respect the antediluvian fossil

Thus, imperceptibly, as it were, proceed the grand operations of
nature, and if accidentally any vast collection of excreta should
happen to be found, as in the guano islands of the dry regions of
America, they seem not to affect the life or health of those animals
which repose on them. It is the same in the dry regions of Southern
Africa, where sheep and cattle, in order to protect them from wild
animals, must, on the approach of evening, be collected into a fold
or kraal, surrounded by a strong fence of the mimosa, and carefully
shut in. On this surface, of no great extent, sheep and oxen stand or
rest for the evening: their excreta accumulate, but do not putrefy,
for the air on the kraal is pure comparatively, and never injurious to
the sheep or cattle; the surface of the kraal is, moreover, generally
dry, even when the soil may be accidentally inundated by rain, which,
when it falls, as it does occasionally, descends in torrents. From the
African soil is thus withdrawn by man the excreta of all the domestic
animals; the semi-barbarous Boer never returns it to the soil, and
thus the loss is permanent; but it would seem that this loss, caused
by man’s interference, in no shape, as far as can be observed, affects
the fertility of the soil, called on to reproduce only the native
pasture, or the wild herbs natural to it. It is otherwise when man
demands from the soil heavier exhausting crops of wheat and hemp,
tobacco, &c.: his interference with nature’s balance must be gone
into, or soon his hopes of a harvest would be in vain. Then comes the
theory of manures, a theory beset with difficulties, and which, besides
involving man in much labour and expense, is productive, or presumed
to be on sufficiently probable grounds the cause, of some, if not of
many, of the diseases which afflict humanity. However this may be,
whatever be the extent to which a dense population and a neglect of the
so-called sanitary regulations subject man to infirmity and disease,
one thing is certain--he has interfered with nature’s balance, and
must take on himself the whole task. If he shuts up a harbour mouth,
refusing entrance to the tide, confining within the harbour a portion
of that ocean water which nature intended should be constantly agitated
by tides and currents, he may expect as results that the shores of
that harbour will soon become uninhabitable by man. All animals
instinctively shun the sick, leaving them apart; man crowds them
together into close, ill-ventilated hospitals, sweeping off in hundreds
those whom the battle had spared.

It were foreign to the object of this work to enter more fully into
the history of that dissolution of animal structures which forms so
important a part of the materials we call manure, destined to restore
to the soil that which artificial crops had deprived it of. Every part
of animal bodies owes its origin to vegetables or plants, no part being
formed by the vital force, and thus all the remains of animals of
necessity form manures.

On the management of these, man’s civilization depends; without
agriculture there can be no dense population; without the dense
population there can be no civilization. On these points many
remarkably erroneous opinions have been, and still perhaps are,
maintained even by practical men, who nevertheless are often in
error--merely, it is true, as to the theory on which they fancy they
act, more rarely as to the practice they have from experience adopted.

In calmly considering this important question--the right management of
manures composed of the excreta or the remains of animal and vegetable
life, it becomes evident that several problems, atmospheric as well
as terrestrial, remain yet to be solved. The surface of the soil,
as modified by man’s labour, presents itself under a very different
aspect to what nature intended it to be. A lake may be drained with
much advantage to a country, but the surface so exposed cannot be too
soon cultivated, to prevent the spread of fevers sure to arise from
the decaying, fermenting, and putrefying of the lower forms of animal
and vegetable life thus brought into existence, especially when aided
by those epidemic constitutions of the atmosphere striking directly at
man’s existence on the earth.

For civilized man there is, there can be, no repose. There are forces
in nature against which, with all his industry, he may never be able to
prevail. The tropical forest returns upon him the instant, as it were,
that he ceases to hew it down, obliterating in an incredibly short time
all traces of human labour. The lands of Western France can scarcely be
secured from the inroads of the sands driven by western gales towards
the interior; the bog is checked only by constant labour, and the hill
where once the heath grew spontaneously, can only be retained in a
green and grassy condition by the constant watchfulness and labour of
men. Twenty years of neglect suffice to restore the heath, and to sweep
away all vestiges of human culture.[33]

  [33] The “Sunderland Times” gives publicity to the following
  frightful narrative, drawn up by Captain Edward Robinson, of
  Sunderland, commander of the ship _Raleigh_, of South Shields:--“I
  arrived at this place in the beginning of May, 1858, being sent
  to bring home a vessel whose captain died of yellow fever; little
  did I think, before leaving home, that I should have witnessed the
  sufferings of so many of my fellow-creatures that were ill of this
  dreadful epidemic. I was told it would be all over before I arrived,
  but I found that, so far from that being the case, its ravages were
  unmitigated. In the street that I lodged in, five in one family were
  buried from the house in one day. The Rio journals were publishing
  in their columns, ‘No cases of yellow fever to-day.’ One ship at the
  port had seven captains dead before she could be brought out of the
  place. The vessel--the _Raleigh_ of South Shields--that I have come
  home in command of, had her captain, chief officer, second officer,
  and four of her crew stricken down by the disease. On the day before
  the Captain died I visited him at the hospital; I there witnessed
  such sights as I hope never again to see--poor sailors in the height
  of the fearful malady, with the black vomit, vomiting dark fluid
  like coffee. I shall never forget the looks they gave me, and how
  their poor dull eyes brightened as I gave them a word of comfort, and
  told them they would get better. Next day, when I returned to see
  them, I found the whole gone--the captain and six of his crew, all
  dead and buried. Still, ‘No cases of fever,’ say the Rio journals.
  The number carried off by yellow fever from February to May, 1858,
  amounted to 1609, upwards of 600 of the deaths being among English
  sailors. The presence of a plague fever is not to be wondered at, the
  state of the town being a disgrace to civilized people. All manner of
  filth is to be met with in most parts of the town. Dead animals and
  filth I cannot describe meet your eye and offend your senses almost

  “My brother, now sixty-eight years of age, and who has been
  thirty-six years at Rio, informs me that he has often seen Europeans
  on ’Change in the morning, who died and were buried on the same
  evening. He has seen Rio cleared five times of Europeans. The
  pestilence, he believes, comes from the flat marshy land near Rio.
  The natives burn tar-barrels to purify the atmosphere.”



§ 1. The question of acclimation is not confined merely to man’s
transfer from one country to another, and to his attempts to
accommodate himself to the new locality, to the altered circumstances
of his adopted country. As civilized man traverses the earth in
search of new abodes, he carries with him the arts of social life,
and especially the art of agriculture, by which alone he can exist in
congregated masses: agriculture, which forms indeed the very basis of

Whether we view man as a native of the land or a stranger, he cannot
evade this question; for even as a native and as an individual of a
race whose presence on the soil he may inhabit precedes the records
of authentic history, if he form a portion of civilized society he
receives from his ancestors or predecessors a system he is bound to
improve, or at least to maintain, so that he shall live and thrive,
not as the beasts of the field, but as a member of a civilized people.
When a hunting tribe of North American Indians, a horde of Bedouins,
or Hottentots or Caffres, a Turcoman family, or a gipsy encampment,
a Cape Boer, or an Australian sheep-farmer, sit down by stream, or
valley, or lake, they no more influence the soil than a troop of
antelopes or buffaloes. Nature’s great processes go on unaffected:
they deteriorate, it is true, by respiration, the superincumbent
atmosphere, but not more than any equal amount of animal life. This
deterioration the wild plants around, sown by nature herself, speedily
removes; the oxygen consumed by savage man and the animal life around,
equally wild, is speedily renovated by vegetation, and the oxygen they
remove from the atmosphere and the carbonic acid they pour into it,
rapidly and constantly recover their equilibrium under the influence
of vegetation. Thus, neither the earth (soil), air, nor water, is in
any way influenced by his presence, nor is he in general affected by
these; there is no reciprocal influence for good or bad: he cuts down
no forests, grows no wheat, or but little, makes no canals, drains
no marsh-lands, poisons no rivers; the refuse of his dwellings, the
excreta of such a population, are not sensibly perceived, even if
allowed to rot and waste away on the surface--a practice prevalent with
most if not all wild and uncultivated people; it rapidly disappears,
disintegrated by processes in which the lower forms of animal life take
a part. Now, contemplate the picture civilized man presents, and see
him in direct antagonism with nature! The plants of nature’s sowing are
rudely torn up with the plough and destroyed, the fields are forced to
yield crops by which he lives, and what he takes from the soil must,
to use the language of chemists, “be restored to it:” the excreta of
man and animals, the refuse of dwellings, the deteriorated and poisoned
liquids, the products of manufactories, are collected into heaps, to
rot on the surface of the soil, before being dug into it; or are thrown
into the rivers, to poison, in a certain sense, the waters on which
man lives, rendering their banks, if not pestilential, at least most
unpleasant as human abodes; canals are dug, vast reservoirs are formed,
which in time give rise by mismanagement to fevers, intermittent and
others; the minerals of the earth are quarried and placed on the
soil, mines are dug, and from them waters are discharged into the
neighbouring streams, strongly poisoned with the metallic ores. To
imagine that an influence thus affecting earth, air, and water can
proceed and increase without affecting human life, can be overcome by
habit, does not require to be met by counter-influences originating in
the experience and reasoning of man himself, is a supposition which the
history of large cities refutes. The influence is reciprocal. When man
thus acts on the three elements of nature by which he lives, they react
on him, and it is this reaction he is called on to meet and to overcome
as best he can. It is a question of reason and experiment--that is, of
science and of simple observation; simple observation and experiment
taught the native Peruvians the value of guano, for science had at
that time no standing on the American continent; and now the chemist
steps in and explains why it was that the experiment proved successful.
Whether his explanation be satisfactory or not, touches not the
question; though proved to be erroneous in a single instance, as it
possibly is in regard of this very Peruvian guano, science stands on
too secure a basis to require any defence from me.

It is one of the conditions of civilization, that man must everywhere
accept the social system within which he lives. Whether a dweller in
detached cottages and farm-houses, or congregated into townships and
villages; collected in masses, as in towns and cities, his endeavour is
to protect his dwelling from all that is offensive and from whatever
may prove injurious to the health of himself and family. An ancient
adage tells us not to act contrary to nature; but as nature reveals
nothing to us, as her intentions can only be read by the lights of
science and reason, or science based on observation and experiment,
whence human reason draws deductions conformable with its power, so
is it most difficult for man to say what is best to be done under all
circumstances. When a man builds a cottage, a house, or a palace, after
duly attending to the surface-drains, he constructs near his dwelling,
sometimes beneath it, a cesspool and a dead-well, the former intended
to receive the more solid excreta, the latter the soil-water of the
kitchen--the water, in fact, used in the domestic economy of the house.
If the dead-well or pit dug to receive the soiled water of the house be
sufficiently deep, it filters through the soil, and thus requires no
clearing out--if not, it overflows the court or garden, and speedily
renders the place uninhabitable. The cesspool, if deep enough and
properly secured, remains for many years unknown and unperceived, until
filled; it may even be forgotten altogether, and its very existence
remain unknown, until disclosed by accident; but whatever be its age
or condition, so soon as its contents are exposed to the air, it is
found to have continued unaltered; and if spread on the fields, as I
have seen done, renders the vicinity for some time unendurable, thus
proving the sagacity of the Jewish legislator in his instructions to
that people to whom he gave laws and regulations to serve them for all
time to come.[34]

  [34] Deuteronomy xxii. 12.

If the adage I have quoted above be true--namely, that we must not
act contrary to nature--there is another of the truth of which we
feel more assured. It is this: whenever man interferes with nature, he
must take the whole matter on himself, and be prepared to meet every
contingency. Nature gave us streams and rivers more or less pure, whose
banks are more or less salubrious. If man pours into these streams and
rivers the refuse of towns and cities, he must be prepared to meet the
result of the experiment. It may be good--it may be bad to him: this
he cannot know beforehand; but reason tells him that the experiment is
likely to prove injurious. It may be less injurious than burying the
excreta in cesspools under his house, or court, or garden;[35] but this
I doubt. In the meantime, how does civilized man protect himself from a
source of disease respecting which there never was a doubt--the natural
humidity of the soil on which he has erected his dwelling, in which he
sleeps and lives? To meet this evil he forms surface drains around his
house and garden and court. Into these collect the humidity natural to
the soil, as well as rains of heaven. These drains, adulterated by no
intermixture with the refuse of house and stables, terminate in the
nearest streams, and serve to maintain these streams and rivers into
which they flow at their natural standard.

  [35] The Registrar-General consoles the inhabitants of London on the
  relative amount of injury, being in favour of the plan of polluting
  the Thames rather than of gradually abolishing cesspools.

Thus, before it was discovered that the best way of dealing with these
difficult questions was to break down the distinction between drain
and sewer (thus poisoning, probably for all time to come, the air of
towns and cities), construct a sewer which soon becomes a cloaca to
receive all, and in open day and above ground throw the contents into
the nearest stream--imitating old Rome, without knowing anything of
Rome’s municipal economy, our forefathers drew a marked and clear
distinction--1st, between drain and sewer; 2nd, between a cesspool
and a dead-well; 3rd, between the excreta of man, which they knew
to be offensive, and that of animals, which all were well aware are
innoxious: the latter they restored to the fields, the former they
disposed of as best they could.

Society, having rejected in this instance the experience of their
forefathers, enters now on a new phasis. Nature, about which they talk
so much, will not suffer them to rest half way. Bad odours pervade
the streets, courts, and houses: rivers can scarcely be approached.
Chemists affirm that that which is thrown into the sea should be
returned to the land. It is this question, in so far as it bears on the
matter discussed in this chapter, I shall now briefly discuss.

There lie before me the “Letters on Chemistry” of an illustrious German
chemist.[36] They contain the expression of the latest scientific
results hitherto attained. Whatever view those who follow us may adopt,
we must in the meantime accept, to a certain extent, of those contained
in these “Letters.” A phenomenon must be accepted as a fact until
refuted by another; and the last experiment, until refuted, expresses
the nearest approach to that truth which, up to the moment, man had
been able to attain. Simple observation tells man many truths. It
shows him that out of grass, herbivora, or grass-eating animals of all
kinds--from the timid hare to the swift and powerful horse--from the
fierce buffalo to the sagacious and irresistible elephant--find the
means for forming muscle and bones, viscera and skin. Out of a similar
food man himself, though no doubt omnivorous, can also derive the means
of support. The rice-eating population of India are not deficient in
energy; whilst it is equally certain, though less surprising, no doubt,
that out of that which once was a living animal, man and the carnivora
derive a considerable part of their subsistence.

  [36] “Letters on Chemistry.” By Justus von Liebig. London, 1857.

No experiments can set aside these simple views, which indeed form the
basis of all inquiry; but civilized man, as I have shown, appeals to
the soil mainly for support. He trusts to the cerealia, and to those
exuberant and abundant crops of legumina and of grains required for the
support of herds of animals, which the uncultivated field could never
maintain. Hence arose agriculture, the most useful of all the practical
arts--not yet a science, but likely in time to become one.

Chemists assert--and I see no reason to doubt their experiments--that
the ash of the blood of graminivorous animals is identical with that
of the ash of grain; the incombustible constituents of the blood of
men, and of such animals as consume a mixed food, are the constituents
of the ashes of bread, flesh, and vegetables; the carnivorous animal
contains in its blood the constituents of the ash of flesh.[37] All
these substances ought to be found in grass alone.

  [37] Liebig, p. 384.

In these processes it would seem that phosphoric acid plays a most
important, and, as it would seem, an essential part. To this I
shall return: at present I merely consider man’s influence on the
soil or earth he lives on, what he derives from it, and what he
returns to it, and in what form it is and ought to be returned.
If it be true that without trees there would be no underwood, no
corn, and no crops,--for trees attract the fertilizing rain, and
cause the springs perpetually to flow which diffuse prosperity and
comfort,--then assuredly man ought to be most careful in interfering
with nature. It is the remark, I think of the illustrious Humboldt,
that when the white man took possession of certain districts of North
America, vast forests prevailed everywhere. On taking possession,
experience showed that agues prevailed, and that wheat might be grown
successfully. The forests have been now destroyed, and agues have
disappeared; but phthisis pulmonalis prevails, and wheat no longer
grows to maturity. We interfere with the soil as nature made it when
we force it to produce from one acre the natural produce of ten; we
interfere with the processes of nature when we load the air with the
products of thousands of furnaces, manufactories, and the poison
exhaled from poisonous rivers and brooks; and we interfere with nature
when we alter the constitution of those streams and rivers from a
natural to an artificial state, loading them with the refuse of our
artificially-drained fields, &c.

Let us listen to Liebig on a matter to which he has given the utmost
possible attention:--

“Experience in agriculture shows that the production of vegetables on a
given surface increases with the supply of certain matters, originally
part of the soil which had been taken up from it by plants--the excreta
of man and animals. These are nothing more than matters derived from
vegetable food, which in the vital processes of animals, or after
their death, assume again the form under which they originally existed
as parts of the soil. Now we know that the atmosphere contains none
of those substances, and therefore can replace none; and we know
that their removal from a soil destroys its fertility, which may be
restored and increased by a new supply. Is it possible, after so many
decisive investigations into the origin of the elements of animals
and vegetables, the use of the alkalies of lime and the phosphates,
that any doubt can exist as to the principles upon which a rational
agriculture depends? Can the art of agriculture be based upon anything
but the restitution of a disturbed equilibrium? Can it be imagined that
any country, however rich and fertile, with a flourishing commerce,
which for centuries exports its produce in the shape of grain and
cattle, will maintain its fertility if the same commerce does not
restore, in some form of manure, those elements which have been removed
from the soil, and which cannot be replaced by the atmosphere? Must not
the same fate await every such country, which has actually befallen
the once prolific soil of Virginia, now in many parts no longer able
to grow its former staple productions--wheat and tobacco? In the large
towns of England the produce both of English and foreign agriculture
is largely consumed. Elements of the soil indispensable to plants,
do not return to the fields; contrivances resulting from the manners
and customs of the English people, and peculiar to them, render it
difficult, perhaps impossible, to collect the enormous quantity of
the phosphates which are daily, as solid and liquid excreta, carried
into the rivers. These phosphates, although present in the soil in
the smallest quantity, are its most important mineral constituents.
It was observed that many English fields exhausted in that manner,
immediately doubled their produce as if by a miracle when dressed with
bone earth imported from the Continent. But if the export of bones from
Germany is continued to the extent it has now reached, our soil must
be gradually exhausted, and the extent of our loss may be estimated by
considering that one pound of bones contains as much phosphoric acid as
a hundredweight of grain.”

Many practical farmers, I am aware, still doubt the facts and theories
of chemistry as applied to agriculture; with them I am free to admit
that agriculture is not a science as yet, but an experimental art. With
this I have nothing to do directly, my object being to show in this
chapter in how far civilized man modifies and influences the soil on
which he lives. He, the practical farmer, clings to farmyard manure,
which he collects in heaps in his farmyard, or by the roadside, exposed
to every change of weather, to drenching rains, to summer heat, and
winter’s cold; from it run in streams over the roads the liquid parts
of the manure, carrying with them the soluble salts; out of what is
left when it has become rotten he hopes to restore to the field what
it lost during the previous crop, and to a certain extent he succeeds;
on the other hand, the chemist argues that the grand object of modern
agriculture is to substitute for farmyard manure, that universal food
of plants, their elements, obtained from other and cheaper sources
retaining its full efficacy; and this can only be done when we shall
have learned, what as yet we know but imperfectly, how to give to an
artificial mixture of the individual ingredients the mechanical form
and chemical qualities essential to their reception, and to their
nutritive action on the plant; for without this form they cannot
perfectly supply the place of farmyard manure. All our labours must be
devoted to the attainment of this important object.

However this may be, and however it may be explained by the chemists,
it must be admitted that to the accidental discovery of bone manure
England owes many turnip crops, and to the introduction of guano from
Peru and Ichaboe crops of wheat which no other manure as yet known
could have produced. Peruvian guano, the best of all, is the excreta
of a sea bird; these excreta, placed in a clear and perfectly dry
atmosphere, have been exposed for centuries to a tropical sun; no rain
falls on the heaps, trodden down only by the gentle feet of the birds

That out of such a product there should arise so excellent a manure
surpasses all previous reasoning derived from mere science.[38] It is
obvious, then, that much still remains to be discovered. Were any proof
of this required, we might refer to the agriculture of China, where,
as has been reported, human excreta alone are used as manure, and with
a success unequalled in any other part of the world. In that singular
land they have discovered much, or using perhaps the discoveries
of preceding races, have turned them to the best account. Their
agriculture is said to be perfect.

  [38] The guano of sea-birds when exposed to rain is of no value.

With such a system of manure and such a population one might predicate
a condition of earth, air, and water, incompatible with human life. Now
the very reverse happens, at least, in so far as regards the Chinese

No land so teems with a population strong, active, and in robust
health; true, it does not suit the European constitution; fever and
dysentery sweep off the troops and sailors of European nations who
visit the Celestial Empire for the purpose of trade or of plunder.
There is a something unknown in the climate unsuitable to the
European; the condition of the earth, air, and water of China, is fatal
to him. In which of these does the noxious element reside--in all or in
none? This is possible; but man in the meantime must decide by what he
knows and sees. Here is a land teeming with life; on land, as on its
waters, millions live; but that life, as regards man, is confined to
the Chinese race, and is unsuited to the European; as regards the soil,
manured in so strange a manner, it also is Chinese. Is it that we,
generally speaking, spread the material in a liquid and vastly diluted
form over the fields, whilst they manipulate and remove from it all
moisture? There may be something in this, for it is known that organic
compounds, above all, are most susceptible of change by the least
perceivable alterations in their constituents. Agriculture is both a
science and an art.

“The clearing of the primeval forests of America, facilitating the
access of the air to that soil, so rich in vegetable remains, alters
gradually, but altogether, its constitution; after the lapse of a
few years no trace of organic remains can be found in it. The soil
of Germany, in the time of Tacitus, was covered with a dense, almost
impenetrable forest; it must at that period have exactly resembled
the soil of America, and have been rich in humus and vegetable
substances; but all the products of vegetable life in those primeval
forests have completely vanished from our perceptions. The innumerable
millions of molluscous and other animals, whose remains form extensive
geological formations and mountains, have after death passed into
a state of fermentation and putrefaction, and subsequently, by the
continuous action of the atmosphere, all their soft parts have been
transposed into gaseous compounds, and their shells and bones, their
indestructible constituents, alone remain to furnish evidence of the
existence of life continually extinguished and continually reproduced.”

If these facts are to be depended on, they explain much of the
influence which man exercises over the soil, and of its reaction on
himself; the hay ague or fever is the produce of his own hands; when he
leaves _on the surface_ millions of tons of fermentable and putrescible
organic remains, he prepares for himself some at least of the diseases
which are to follow. It is possible that epidemic influence, over which
he neither has nor can have any control, might be greatly modified, and
its evil effects abated by prudent action on his part. Typhus fever,
the scourge of modern Europe, may not originate in any condition of
the soil produced by man, but it sweeps thousands in the prime of
life from the earth when placed in circumstances clearly dependent on
man himself. Ten thousand young men are lodged in a barrack; speedily
hundreds of these are swept off by typhus or consumption of the lungs;
now something causes this, and the cause may rest with man himself.
Pestilence and typhus follow in the train of famine; if they originate
in fermentescible and putrescible substances, all these were present
prior to the famine, and yet were not equal to the production of the
maladies. Next comes famine, and prepares the way for malaria to do
its work. The question, as may be already seen, is not so simple as
chemists supposed it to be. The number of substances occurring in
nature which are truly putrescible is singularly small;[39] but they
are everywhere diffused, and form part of every organized being. To
form an idea of what this amounts to, we have but to reflect on the
life which naturally exists on the earth, and on that which is the
result of man’s social condition. Let but the acre of heath or bog,
even of pasture, which in its natural state supports so little of what
lives, be converted into a garden, a wheat field, a nursery, and see
what an amount of putrescible matter is the result. Let that spot on
which nature has placed a single peasant’s family be converted into a
city, and reflect on the influence man exerts on that soil. It is, I
believe, a fact universally admitted, that all those substances which
destroy the communicability or arrest the propagation of contagions and
miasms, are likewise such as arrest all processes of putrefaction or
fermentation; that under the influence of empyreumatic bodies, such as
pyroligneous acid, which powerfully oppose putrefaction, the diseased
action in malignant suppurating wounds is entirely changed; that in
a number of contagious diseases, especially typhus, ammonia, free or
combined, is found in the exposed air, in the liquid and solid excreta
(in the latter as ammonio-phosphate of magnesia); such being the case,
it seems impossible any longer to entertain a doubt as to the origin
and propagation of many contagious diseases.

  [39] Liebig.

“Finally, it is an observation universally made, and which may be
regarded as established, ‘that the origin of epidemic diseases may
often be referred to the putrefaction of great masses of animal and
vegetable matters; that miasmic diseases are found epidemic, where
decomposition of organic substances constantly goes on, in marshy and
damp districts. These diseases also become epidemic, under the same
circumstances, after inundations, and also in places where a large
number of persons are crowded together with imperfect ventilation,
as in ships, in prisons, and in besieged fortresses.’[40] But in no
case may we so securely reckon on the occurrence of epidemic diseases,
as when a marshy surface has been dried up by continued heat, or when
extensive inundations are followed by intense heat.”

  [40] Henle, “Untersuchungen,” p. 52; also p. 57.

If we admit these facts we shall be less surprised at the ravages
committed by fever, when, after great battles, the wounded are placed
in the hospitals of large cities, as in Brussels after Waterloo, in
Bilboa, Vienna, &c. Hospital gangrene, the scourge and terror of
the wounded, soon shows itself, and cannot be arrested by any known
surgical means. Much better were it for the wounded that they had been
left on the field of battle. An erroneous opinion prevails, that it is
to the presence of the infusoria that the evil influences are to be
traced; they, on the contrary, whilst alive, act a beneficial part.
The excreta of man whilst putrifying never exhibit the presence of
microscopic animalculæ, whilst we find abundance of them in the same
matters when in a state of decay. “A wise arrangement of nature has
assigned to the infusoria the dead bodies of higher orders of beings
for their nourishment, and has in these animalculæ created a means of
limiting to the shortest possible period the deleterious influence
which the products of dissolution and decay exercise upon the life of
the higher classes of animals. The recent discoveries which have been
made respecting these creatures are so extraordinary and so admirable,
that they deserve to be made universally known.”

It is not to that which lives, but to that which has lived and is now
dead, that we must look for the sources of those terrible fevers which
destroy humanity in so many fine countries. Nor is it necessary that
marshes be present, nor recently inundated lands. Egypt, annually
inundated, is healthy at all times, but it is always cultivated;
the desert also, which is never cultivated, and incapable of any
cultivation, is also healthy. The Arabian desert which skirts the
cultivated spots, converting them into so many oases, is perfectly
healthy; on its soil the traveller may sleep securely; but let him
cross the boundary of the water drain or stream forming the oasis, and
sleep within the limits of that vegetation so delightful to look at,
and violent fever is sure to overtake him on the morrow, so powerfully
in this instance does nature react on man, when altering the soil, he
prepares with his own hand the flowery path which leads him to the

§ 2. _On the Origin and Action of Humus_.--To Liebig we unquestionably
owe the first philosophical investigation into the history of _humus_.
Innumerable difficulties and prejudices beset the inquiry. It was
he who first showed that all vegetables and all their component
parts, so soon as they cease to live, become liable to two forms
of decomposition,--to putrefaction and to rottenness, that is to
fermentation, and to that slow combustion to which Liebig gave the name
of _eremacausis_, a Greek term, expressing by its original meaning
the fact of slow combustion, to which the illustrious German likened
that process which we commonly express by the term of _pourriture_, or
rottenness. By this last-named process the combustible parts of bodies
in decomposition combine with the oxygen of the air.

The decomposition of the rotting of the woody fibre is attended with
this peculiarity--when in contact with the air, it converts the oxygen
into an equal volume of carbonic acid; so soon as the supply of the
oxygen ceases the rottenness stops. Now remove this carbonic acid, and
add a fresh supply of oxygen, and the rotting commences, and carbonic
acid reappears. The presence of water is essential to this change; the
substances called antiseptic arrest it at once. Now the woody fibre in
this condition of slow combustion or rottenness is precisely what we
call _humus_ or _ulmine_.

The functions of this humus are no doubt remarkable, and in respect of
it some agricultural theories have been formed, resting on no solid
basis. What seems to be tolerably well ascertained is, that in a soil
permeable to air, the oxygen of the atmosphere continues to act on
the humus, giving origin to carbonic acid, and thus furnishing an
atmosphere for the roots of plants growing in that soil. The springing
of the roots themselves seems to depend on the presence of this
atmosphere; hence the labour and pains to pulverize the soil, and to
give access by such processes to the atmospheric air. At this period of
their growth the roots perform all the offices of their leaves which
are ultimately to appear; and soon the plant has two sets of nourishing
organs, the roots and the leaves. In hot summers plants derive their
carbonic acid wholly from the air.

Thus gradually is formed that humus or ulmine to which agriculturists
attach so much importance; that vegetable mould supposed to be the
richest of all soils. But where it forms, a kind of putrefaction
continually goes on; the soil is influenced deeply as a residence for
man. No valetudinarian takes up his abode in the centre of a rich
vegetation in hopes of recovering his health and strength, his elastic
step, and freedom from lassitude and weariness; he, on the contrary,
seeks other regions, where vegetation is scant, humus is not forming,
and the soil is never turned over by human industry.

When vegetation is purely natural, that is when man does not interfere,
the growth of plants does not in the least exhaust the soil. Look at
the meadow and the virgin forest! Now chemistry explains this, or
nearly so. But so soon as man _interferes_, he must be prepared to
undertake the whole labour; if he acts on the earth, the air, and the
waters, they will react on him, and sometimes with fearful effect.
Beyond the processes she exhibits, and which he may read as best he
can, she reveals nothing; all her secrets must be extracted from her
by science, by philosophy, by the slow procedure of experiment and
observation. A traveller from a distant land prepares to cross deserts
of which he has had no previous _experience_; shortly he discovers an
oasis, which to him seems a paradise, and he proposes resting for the
night within its treacherous circle; but the wild Arab, the native
guide, knows better, and explains to him briefly that the desert alone
is healthy, and to rest a night within that seeming paradise is death.
It is the Homeric tale of the syrens reduced to a reality; gorgeous
decorated plants, sweet-smelling flowers, perfumes of Arabia, invite
you to enter that island destined, should you unhappily accept the
invitation, to prove the resting-place of all your labours.

It may seem paradoxical to maintain that by cultivation we at times
render the earth insalubrious, at times comparatively the reverse, but
the fact is so. It was Humboldt, as I have already remarked, who said
that when Europeans first emigrated to America, the soil of certain
northern states was found equal to the growth of wheat, and ague
afflicted the population. With the destruction of the forests, the
agues have disappeared, and wheat can no longer be grown; in the place
of agues men are now afflicted with pulmonary consumption. Whoever has
seen the marshy and boggy land, at times a lake, at others a black
tremulous morass, and compared it with the rich drained Polder, its
neat and compact farm-house, exhaustless meadows, herds of cattle, and
the contented air of its well-to-do proprietor, will at once perceive
that whatever might be the evil, unless it were a something truly
grievous, so delightful a metamorphosis of a spot doomed by nature to
eternal sterility, entailed on man, that evil was fully compensated for
by the results obtained towards man’s happiness. There is, there can
be, or at least there never was, any unmixed good on earth: the whole
is a system of comparison and compensation; of profit or loss; of gains
and drawbacks.

When the English army died off at Walcheren the inhabitants of the
province were perfectly healthy, and could not comprehend the cause of
the calamity. It was the same in the Crimea. Under other arrangements,
those more consonant with common sense and experience, the results
might have been different; still it is certain that masses of young
men of immature years cannot be withdrawn from their native soil and
parents’ hearths without suffering severely the consequence of the
every way unnatural position they are forced to occupy; unnatural
physically and morally. Barrack-rooms are not homes. No varied society
is to be found there; no amusement, no employment for mind and body;
it is man cut off from all human industry and enjoyment; no solace
when ill, no comfort under suffering: that young men with unformed
constitutions should “die off like flies,”[41] need excite no surprise.

  [41] The expression of Lord Raglan when he demanded from England
  veteran troops, and not lads of immature age, to be sent to the seat
  of war.

To return: to modern science, above all to Liebig, the practical
chemist _par excellence_, we owe the discovery of the true office of
_ulmine_ or _humus_ in vegetation; it nourishes the plant before it
is in a position to draw its nourishment from the atmosphere. The
vegetation called antediluvian had this peculiar character, that it
enabled the plant to be greatly independent of roots and soil; its
broad-leaved foliage sought everywhere for food in the carbonic acid
of the atmosphere. Accordingly all the plants were remarkable for the
smallness of their roots, which generally have disappeared, and are now
no longer to be found.

Let me now consider briefly--keeping the same object in view, namely,
its influence on man--what are the sources and results of that amount
of hydrogen or azote which plays so important a part in the economy of
all that lives.

An agricultural farmer at a distance from markets sufficiently
remunerative, has a large field of turnips which he knows not how to
dispose of. Not having cattle or sheep sufficient to consume these
turnips, he addresses himself to drivers of sheep on the way to the
markets, inviting them to turn their sheep into the field, and there
remain until the turnips are consumed. Thus he hopes to restore
to the field the azotized and other principles removed from it by
previous crops, and to prepare the way for fresh and more productive
and profitable crops. It is on the same principle that in many
leases of farms (those called steel-bow) there is an express clause
that the straw shall not quit the farm, but be consumed on it. The
object of this is simply to restore to the soil what forced crops
have removed from it. Man has taken on himself the task of growing
on one acre the natural produce of many; to feed twenty men instead
of one from off the same extent of soil; to live in crowded cities,
drawing their provisions from the surrounding country, producing
nothing of themselves; to feed millions where nature intended but a
few thousands should exist; he has taken the task on himself and must
carry it through, exposed to destruction at every false step, and at
this moment exposed to the accusation by the medical authorities of
England of deliberately rendering his farm-house, his homestead, his
cottage, his mansion, his palace, a pesthouse, the propagator, if not
the absolute generator, of all the wide-spread plagues and pestilences,
from that which desolated Athens in the time of Thucydides; laid
waste the Roman world when Justinian reigned; smote England in the
most unhappy and disgraceful period of past history;[42] and now,
appearing amidst the tents of an obscure Arab tribe, ignorant of
agriculture, living with their flocks and herds on the desert, happily
remote from the influences of boards of health, officers of health,
and registrars-general, once more threatens Europe; he is accused, in
fact, of being the involuntary but certain slaughterer of his little
babes. So says the eloquent Registrar-General of England in one of
his sanitary reports; he belongs, it is true, and this must not be
forgotten, to the theory-loving fraternity,[43] a professor, in fact,
of that conjectural art which heretofore despised statistics, and
which now, by mistaking figures for facts, threatens to convert true
science into a scheme of fictions anything but brilliant. To the
Chadwicks, the Gavins, and a host of others still more potent, but who
always act through the agency of _employées_, we owe the affair of
Luton and of Birmingham, of the disgraceful condition of the Thames and
of innumerable other localities; the deodorizing schemes of Leicester
and Bristol, the intercepting scheme of the Thames, and the network of
officers of health, amounting to 2600, now spread over England for the
benefit of this tax-loving country.

  [42] Reign of Charles the Second.

  [43] He is, I believe, a physician and an M.D.

If you hope to raise a crop you must replace in the soil certain
elements which previous crops have removed from it. So says Liebig, and
to some extent the experience of mankind supports the view.

The refuse of men and urinals which English speculators recommend you
to throw into the nearest river, or into the sea if you can, or at
least to deluge well with water before throwing it over your fields,
the Belgian farmer places as nearly as may be under ground until
required. Of it he forms a compost, seemingly inoffensive as being
in some measure buried, trapped, and mixed with house refuse, and
other materials. This compost, to which he looks in due time for the
restoration to his well-managed farm of that which abundant crops had
removed from it, he spreads at convenient and suitable times on his
ground, into which it is speedily dug; thus at every step he reverses
the theories of the would-be agriculturists of England, and should
it be said that the measures he adopts are injurious to his health,
destructive to his family, sources of pestilence to the country, we
have the sure and trustworthy statistics of a true statistician[44]
to oppose to the wild theories and bold assertions of the needy
adventurers and hired officials who, clamouring so loudly for place and
distinction, have chosen for the field of their tactics broad England
and her colonies.

  [44] Quetelet.



§ 1. Although the amount of disease and mortality traceable to
accidents, to the ordinary atmospheric changes of which the thermometer
gives us due information, to the habits of life and the effects of
hereditary influence, be sufficiently great, it yet seems nothing when
compared with the terrible inflictions occasionally and at uncertain
periods visiting man, whether shut up, as it were, within the confined
haunts of cities, or living apart in the open country, in situations
where it might be reasonably imagined no such influences could reach
him. The poison of typhus, for example, if it be a poison, spares
none: in certain epidemics the citizen and the peasant suffer alike:
the strong robust man in the prime of life is its special victim;
cholera attacked the inhabitants of the remote and isolated cottage as
certainly as the careful wealthy citizen, and with the same results.
No mode of life, nor sex, nor age was security against it; no race,
no locality.[45] An inquiry into the origin of such influences is
the most important to which man’s attention can be directed. These
terrible epidemics appear under various forms; sometimes it is by
typhus or influenza, cholera or plague; even those diseases which
seem to be endemic, or confined to a locality, assume the form of
epidemical raging pestilences, and then disappear for a time. Thus
the remittents and yellow fevers of tropical climates do not always
put out their whole strength; there is a lull, a season of repose,
when man, deluded by the security of a few years, hopes that at last
the evil influence has disappeared for ever. Vain hope! It moves
in cycles, like the typhus of temperate climates, falsifying all
predictions. Thus, in Jamaica, the grave of so many noble English
regiments, the fever, sometimes called remittent, sometimes yellow
fever, exhibited its fitful attacks during eighteen years, in the
following capricious manner, at a station called Port Antonio, about
eighty miles from Kingston. At Stoney Hill Barracks, the disease was
still more capricious.[46] As the poison producing intermittents
and remittents must be presumed to be always present, it is
incomprehensible how it should at times cease its attacks on man,
showing that another influence or element requires to be present to
render its attack successful. Again, we find that within a limited
range, a long residence in a land unhealthy to the stranger seems by
acclimation to diminish if not entirely to eradicate the susceptibility
to disease on the part of the latter; but this opinion must be received
cautiously and with reserve, for the phenomenon may be partly due to
the difference in race, respecting which we as yet know but little. The
banks of the Scheldt, the Polders of Holland, and the mouths of the
Rhine, the Danube, and the Indus, are healthy to the natives of these
districts; graves to foreigners. In all inquiries of this kind, these
well-established facts must not be overlooked.

  [45] Cholera has not, as yet, passed into the southern hemisphere
  beyond the tropical line.

  [46] “The town of Port Antonio is situated at the north-eastern
  extremity of the island, eighty miles from Kingston, and lies in
  a hollow surrounded by an amphitheatre of thickly-wooded hills.
  Fort George, in which are the barracks for the troops, is built at
  the extremity of a peninsula, nearly surrounded by the sea; and
  though possessing no great elevation, it has, from its position, a
  tolerably free exposure to the breeze. On each side of the peninsula
  are two harbours for the shipping; that on the east side enjoys a
  comparatively healthy locality, but that on the west is sheltered
  by a thickly-wooded hill, which impedes ventilation; and there is a
  considerable space of level ground, generally inundated by the tide,
  which at low water is left in a marshy state, and when acted on by
  the sun emits exhalations said to be both offensive and unhealthy.

  “The barracks stand about twenty yards from the sea, on a piece of
  ground of coralline formation, and consist of a building of two
  stories, elevated on brick pillars. The hospital is built on a higher
  situation, and raised on arches about seven feet. It contains three
  wards for the patients, and has a shaded walk attached to it for
  convalescents. Water is supplied to the troops, by contract, from a
  river a quarter of a mile distant.

  “There seems to have been no troops at this station in 1825 and 1826,
  but the mortality during the other years embraced in the Report has
  been as under:

  |        |           |         | Ratio of deaths |
  | Years. | Strength. | Deaths. |   per 1000 of   |
  |        |           |         |  mean strength. |
  |  1817  |    177    |    34   |       192       |
  |  1818  |    135    |    12   |        89       |
  |  1819  |    130    |    45   |       346       |
  |  1820  |    143    |    12   |        84       |
  |  1821  |     82    |    18   |       219       |
  |  1822  |    194    |    10   |        52       |
  |  1823  |     79    |     4   |        51       |
  |  1824  |    108    |    21   |       194       |
  |  1827  |     32*   |     3   |        94       |
  |  1828  |    129    |    19   |       147       |
  |  1829  |    133    |    31   |       233       |
  |  1830  |    155    |    21   |       135       |
  |  1831  |    161    |    20   |       124       |
  |  1832  |    157    |    29   |       185       |
  |  1833  |    164    |    37   |       226       |
  |  1834  |    185    |    32   |       173       |
  |  1835  |    154    |    18   |       117       |
  |  1836  |    160    |     4   |        25       |
  |  Total |   2478    |   370   |       ...       |
  |Average |    137    |    20   |       149·3     |

  * 127 men were here for one quarter of a year only,
  which is equivalent to 32 for a whole year.

“Thus the local circumstances remaining the same, the mortality from
fever yet varies exceedingly. It is the same with the typhus of
temperate countries, showing that in addition to malaria, presumed to
be ever present, a something more is required, that we must look for in
the constitution of the atmosphere.”

§ 2. When a chemical substance is applied externally or internally to
the living tissues of an animal sufficiently strong to dissolve the
affinity between them and the vital force, and to substitute for it
other stronger affinities, the explanation of the phenomena is easy,
and the coarsest chemistry offers a solution. The action of caustic
potass, of concentrated sulphuric acid, present the examples of this
kind of dissolution. Other substances alone poisonous when given in
concentrated doses, are known to pass, when sufficiently diluted,
through the blood, and be eliminated by secretion and excretion from
the body: after causing disturbances more or less grave, more or less
important, the combinations they form, if any, with the living organic
molecules are overcome by the vital force, which then resumes its usual
influence. Of such substances some pass off unaltered, others are
decomposed, and the bases only appear in the secretions or excretions.
Whilst passing through the lungs, certain of these vegetable salts
combine with the oxygen of the air, and the respiration in consequence
becomes slower, or in other terms, they diminish the production of
arterial blood.[47]

  [47] I am free to admit, with Liebig, that the lungs are the seat
  of the most rapid and powerful chemical action (p. 151), yet some
  distinguished physiologists think that the external integuments may
  become the seat of disease, and give origin to dangerous affections
  by mere stoppage of their secretions and excretions. Certain of
  these are held to be poisonous and highly irritating, and cholera
  itself has been ascribed to the sudden transfer of the tegumentary
  secretions into the general torrent of the blood. This seems to have
  been the opinion of the celebrated anatomist and physiologist, De

Now, these salts[48] when placed in contact with animal and vegetable
substances, perform the same function as in the lungs: they take a part
in the combustion going on, and, as in the living body, are converted
into carbonates. Left to themselves for a time, from their aqueous
solution, the acids composing them finally completely disappear.

  [48] Citrates, tartrates, acetates.

Mineral acids and nonvolatile vegetable acids, as well as mineral
salts with an alkaline base, have the property, when sufficiently
concentrated, to arrest the whole process of this slow combustion;[49]
common salt, as is well-known, arrests putrefaction: so does alcohol.

  [49] Eremacaasie: Liebig.

The chemical action of certain other mineral salts is different, such
as the salts of the peroxide of iron, of lead, bismuth, copper, and
mercury. These are inorganic poisons. They combine with the tissues of
the organs, and so destroy life. The mode of action of the poisons of
prussic acid, strychnine, morphine, &c., is as yet unknown.

“But there exists a class of substances no less fatal than the
preceding, originating in certain decompositions. In a preceding
Chapter (III.) we have inquired into the origin of these poisons, and
shown them to originate in fermentation and putrefaction. Let us apply
the chemical principles regulating these processes to organic matters,
to the products of the animal economy; all the elements of these
matters are derived from the blood, the most complex of all existing
substances. In decomposing, a poison is occasionally produced speedily
mortal when it comes in contact with the blood of the living animal.
The venomous principle produced by decomposing animal bodies is not
always the same: that originating in certain German sausages is quite
peculiar; the person who partakes of this fatal dish dies mummified;
he does not rot or fall to pieces like those who perish from wounds
received in dissecting-rooms; on the contrary, he dries up and withers,
but does not putrify.[50] Liebig, the discoverer of this poison and its
effects on man, states that the venom is destroyed by boiling-water and
alcohol, but that these do not absorb it.

  [50] All constitutions are not equally liable to be affected by
  morbid poisons. This has been proved as regards dissecting-room
  wounds; and as regards typhus, cholera, plague, ague, &c., the matter
  admits of no doubt.

Similar in the mode of action on the economy are the poisons of
small-pox, plague, &c. The substances which arrest fermentation and
putrefaction, also neutralize the power of these poisons; but the
essence of these poisons has not yet been obtained in an isolated
form, and thus nothing positive is known of its real nature. One thing
seems certain; contagions, poisons and miasms are not living beings
nor animalcules, any more than yeast. They may be, and probably are,
produced by fermentation, but this is neither caused by nor terminates
in the formation of living animalcules, to which all or any of these
phenomena might be attributed.

A nice distinction has been drawn by a distinguished chemist between a
contagion properly so-called and a miasm. When the disease-producing
matter is the product of a disease, it is a contagion; if it be the
product of putrefaction or of eremacausis of any substance, animal or
vegetable,--does it act by virtue of its chemical character, and not
of its condition (_etat_), in forming a combination, or in causing a
decomposition, it is then a miasm.

The history of diseases so originating scarcely supports this view.
Typhus, which at times seems to originate in a miasm, at times seems to
assume a contagious character. The same may be said of yellow fever.
But however this may be, the distinction applies to such diseases
as intermittent and remittent fevers, which originating in a miasm,
itself springing from the putrescence of animal or vegetable bodies,
gives rise to disease which does not reproduce the miasm. Now, between
diseases so produced and those arising from contagion properly so
called, there is this remarkable distinction: the blood once altered
is no longer susceptible of the same contagion, whereas against miasms
there is no such security.[51]

  [51] Blood has a _mordant_ given to it which dyes it red; when
  this is in excess, the blood becomes black, or very dark. This was
  the colour of the blood in cholera. Its crasis seemed to be broken
  down, and I have it on sure anatomical testimony, that in dissecting
  those who had died of cholera, the larger veins, when once opened,
  continued to pour out blood for many days.

In every contagious disease, and perhaps even in those simply arising
from miasms, there is an odour which fills the chambers of the sick,
and is recognisable at once. Ammonia is very generally present, as it
is wherever animal decompositions are going on, that is, putrefaction.
The foul airs emanating from stagnant and neglected ditches is
composed, as has been long known to chemists, of carbonic acid and
sulphuretted hydrogen gases, and these are viewed by some as amongst
the most dangerous of miasms. These gases may be destroyed by acid
vapours now in common use.[52] From chemistry we also derive another
valuable lesson in respect of substances directly destroying human
life. The materials ready to undergo putrefaction, and thus to generate
miasms, may all be present, and yet no miasms are given out, and man
escapes; this security depends upon the absence of that third principle
requisite to bring the others into activity.

  [52] The various plans for the deodorization of cesspools,
  water-closets, dead-wells, sewers, &c., were first introduced into
  England from France and Belgium. Under French management Paris
  is sweet, and proverbially clean and pleasant; London, under the
  management of parties without individual responsibility, notoriously
  filthy and full of bad odours. Under certain circumstances, and
  especially when limited to small quantities of the matter to be
  deodorized, they are successful enough in destroying the unpleasant
  odour, but in the experiments made a few years ago on the comparative
  merits of various kinds of deodorants, it was obvious that no real
  dependence could be placed on them, unless the cesspool was at the
  same time flushed or cleansed out with a very strong flow of pure
  water poured in along with the deodorant. In how far the various
  deodorants recommended are at the same time disinfectants, has never
  yet been shown.

  The _excreta_ deodorized have hitherto proved of but small commercial
  value, farmers very generally declining their use. It is singular
  that the same _guano_ (human) which is said to be so valuable in
  China, should prove a failure in Europe, and especially in England,
  showing how much still remains to be discovered in practical
  agriculture. If human guano really be of such value in China as has
  been reported, might it not be worth while to import into Britain
  a few Chinese agricultural labourers and gardeners thoroughly
  acquainted with the agriculture of their country, and from whom might
  be learned the art of preparing the manure? Capitalists have engaged
  in many less promising speculations than this.

  From whatever source the Chinese derived their knowledge of the
  domestic and fine arts they now possess (for it is impossible to
  imagine that they invented them), one thing is certain--that they
  were recording eclipses, printing books, building temples, raising
  crops equal to the support of a vast population, whilst the great
  nations of Western Europe were wandering about in their native woods,
  clothed in the skins of animals, ignorant even of agriculture, and
  barbarous to the last degree. Nor was the knowledge and taste of the
  Chinese confined, in the matter of agriculture and horticulture, to
  the merely useful, as is obvious by a passage in Humboldt’s “Kosmos,”
  wherein the illustrious savant proves that the ancient Chinese, in
  respect of taste in horticulture, and in the composition of park
  scenery, excelled all the world.

Thus it happens that in his extensive and elaborate inquiries, Major
Tulloch was continually met by difficulties which overthrew at once all
existing medical theories, rendering it even probable that the supposed
relation of cause and effect between marshes and miasms, and miasm and
fever, was merely accidental. In what that third element consists,
that immediately exciting power which urges on the decomposition to
an extent it had not before attained, rendering that miasm mortal, or
at least most dangerous, which heretofore the vital force was able to
resist, has not yet been discovered.

Is it electricity? is it ozone?[53] or does it depend on some unknown
principle in the elements of the atmosphere, for the detection of
which we have no instrument? Does security in such cases depend on the
presence in the atmosphere of some such principle as ozone? Whatever
be the cause, the fact is certain; epidemics follow cycles of increase
and decrease; like comets, they come and disappear at long intervals.
Our business in the mean time lies with what is constantly present, in
a more or less aggravated form--the malaria continually reproduced,
always efficient in certain regions of the earth; in the overcoming of
which, as I have endeavoured to show, well-directed human industry is
far from unavailing.[54]

  [53] Ozone is said to oxidize the poison. It destroys sulphuretted
  hydrogen and all oxydable miasms, and is the most powerful
  disinfecting agent, but is itself unfit for respiration: it causes
  suffocation. Air in its normal state contains one ten-thousandth part
  of ozone; when raised to one two-thousandth part it is sufficient to
  kill small animals.

  [54] Hydrogen, or inflammable air, is the lightest known substance;
  its specific gravity is to that of air as 732 to 1000. The gases,
  into the composition of which it enters, rising from these ditches
  and banks of mud carry with them dried humus, and even animal matter
  in a state of putrefaction, which, being dry or moist, may act as
  strongly as variola itself, in respect of its injurious effects on
  man, who breathes it either as it rises from ditches, or is driven by
  currents of air circulating round watery places covered with humus.
  It is even (_onctueux_) so strong that it will sustain seeds and dust
  upon water, as I have witnessed at Amsterdam, Rotterdam, Verona,
  Bologna, Venice, and even in the canals of Lambeth and Deptford.
  By means of hydrogen we raise a balloon; can we not imagine it to
  be equal to the raising up of humus? It is generally supposed that
  sulphuretted hydrogen is amongst the dangerous miasms, but it cannot
  be so hurtful, for no boat can go into canals without disturbing it,
  and yet we see no evil results from this; but if the water-level
  lowers, and leaves vegetable or animal matter upon mud in a state of
  slow combustion, then it is that fevers commence--a fact, I think, I
  have proved by an appeal to the history of pestilences in ancient and
  modern times.



If the servitude of rivers be the noblest and most important victory
which man has obtained over the licentiousness of nature,[55] then
assuredly ancient civilizations bear away the palm in this respect from
the modern, and Britain must be permitted to occupy perhaps the lowest
place in the scale of those empires and nations who, by their industry
and knowledge, overcame the difficulties which the right management of
river courses presents to civilized man.

  [55] “Decline and Fall,” vol. iii. p. 391, Milman’s edition.

More than forty centuries ago the Nile was completely at the service of
the ancient Egyptians, and the prosperity of Babylon and Nineveh leaves
no doubt as to the subjugation of the Tigris and the mighty Euphrates.
To come to later times, the Rhine itself, even in the days of the
early Roman emperors, must have been subjugated by the labours of the
primitive Batavians, and the revolt of Civilis, with his Batavian
legions, testifies as to the energy and intelligence of the race. And
now by the patient industry of their descendants, that land, seemingly
doomed by nature to be wasted on one side by the turbulent ocean, on
the other by the great rivers which traverse it, presents a spectacle
unequalled in the world. Even the despised Oriental race of China, that
unsolved problem in the history of mankind, whose capital the combined
forces of England and France now threaten, seems never to have had a
difficulty in mastering the great problems which the necessity for the
subjugation of rivers forces on civilized man; the Chinese waters have
been turned to the most profitable account; their deltas seem healthy,
and abound with life, with Chinese life, at least. The great rivers of
the Celestial empire give no trouble to its inhabitants; agriculture is
said to be perfect; no one seems to have proposed to throw the refuse
of Pekin into the nearest stream, that stream too, as it might happen
to be, the source from which the inhabitants of the capital obtain the
water required for their manufactures and for the arts of life.[56]

  [56] The idea of employing the drainage of towns, partaking under
  all circumstances more or less of the nature of sewage--using the
  term in its most extensive sense, as comprising the excreta of the
  entire population--seems first to have originated in Scotland, and
  especially in the vicinity of the capital. The period is perhaps not
  well known, but about the commencement of the present century we find
  the system in full force, but limited to the great outlets of the
  drainage and soiled water of the town. These great drains were not
  strictly speaking sewers, but drains, for at that time there were
  but few sewers, properly so called. If cesspools existed, they were
  not emptied into the drains, or so-called town-sewers, so that the
  matters contained in the two great outlets used for the purposes of
  _foul-water irrigation_ bore little or no resemblance to the turbid,
  frightful, and most putrescent mass _now_ conveyed into the Thames by
  the sewers of London. This essential distinction in the quality of
  the material has been ignored or passed over in the Reports of the
  Board of Health. Not that the irrigating water was to be considered
  as pure; on the contrary, it was extremely filthy; but it did not
  _at that time_ contain the sewage of the town, properly speaking. It
  probably now does so in consequence of the extension of the system of
  water-closets, latrines, &c. The Scotch agriculturists who employed
  the water of these vast foul drains, would have much preferred _pure
  water_, but they had it not at their command. With this, such as
  it was, they irrigated certain tracts of land, some of which were
  originally barren wastes, converting them into meadows on which grew
  a peculiar kind of grass, which cattle (milch cows) do not reject
  after having been accustomed to its use. But the farmers knew well
  that the abominable liquid they thus poured over their fields was
  wholly unfit for the usual agricultural purposes; and thus in no
  instance did they employ it as manure. The Grange drain was used
  by one market-gardener only, simply for the purposes of irrigation
  during droughts, but not with any view to the manuring of the garden.
  By the time that all the cesspools of London have been poured into
  the drains, and the system of drainage and sewage completed and
  formed into one system, there arises the question as to how the
  material is to be disposed of? The pouring it into the Thames at a
  point below the influence of the tide is perhaps, after all, the
  easiest and least expensive mode of escaping from the dilemma into
  which the capital has been brought by the clumsy experiments of the
  late Board of Health; but what the ultimate result of this additional
  experiment may be, no one can foretel. If transmitted to the fields,
  the farmers are sure to reject it as manure; but it might be conveyed
  to barren waste lands, mere sandy wastes, the qualities of which no
  doubt in time it would beneficially affect, converting them first
  into meadows, and possibly afterwards into land favourable for the
  growth of certain green crops. The liquid might also be conveyed to
  estuaries which it might be desirable to fill up, and the numerous
  small tidal harbours which the extension of railways will speedily
  render of little or no value to the inhabitants.

  The mud deposited in tidal harbours or on the banks of rivers within
  the influence of the tide is of no value as a manure; when spread
  over the fields, the result is the loss of the crops for some years.

Civilization on the banks of the Thames is no doubt very different and
very superior to what it possibly can be on the banks of the Yellow
River, but as, _non omnia possumus_, as different races and nations,
like individuals, have each their peculiar excellences and forms of
civilization, excelling in some, deficient in other qualities of
mind and body, it may undoubtedly happen that even the English of the
present day, the most perfectly civilized nation on the earth, or
that ever lived, might take a hint from some other nations on points
respecting which their otherwise inimitable genius seems to show some
slight deficiencies. As regards art, for example, we owe some hints
to the pitiful States of ancient Athens and Corinth; the despicable
Copt had connected the Mediterranean and Red Sea by a canal--the art
of re-opening which seems now to be lost; even the miserable native
Peruvian and Mexican had carried the arts of mining, of irrigation, and
the use of artificial manures, to an extent which surprises the men of
modern times, who, in Britain at least, think that civilization really
only appeared in the world during the reign of Queen Anne, as in France
the era of the Grand Monarque is universally admitted to be the period
when the French nation first threw off its primitive barbarous and
Celtic form of civilization, assuming the character and social habits
of that race to whom they owe their name, though not their descent. If
we cast our eyes over the surface of the earth, aided by the lights,
somewhat obscure, no doubt, of history, certain facts rising above the
ocean of detail appear as landmarks. The philosophic historian points
to, as peculiarly within his province, the transfer of the seat of
power from nation to nation, from race to race; how before Alexander
appeared there seemed to have been a Sesostris; after the son of Philip
came Julius the Dictator; then Napoleon; and drawing conclusions
as to the future from the past, historians see no improbability,
at least no impossibility, in New Zealand, after the lapse of many
centuries, producing the Hume of the southern hemisphere; whilst a
future capital arising in the desert regions of Siberia or Northern
America, may one day dictate to the world.[57] Ever at variance as
to the rise and fall of empires, they are yet agreed as to certain
facts and circumstances, many of which are still verifiable by the
geographical distribution of the existing rivers and mountain regions
of the globe; and even if man, in the plenitude of his scepticism,
were disposed to doubt, monuments exist, the undeniable work of human
hands, under circumstances implying the existence of a social system
which cannot well be misunderstood. “In the boundless annals of time,
man’s life and labours must equally be measured as a fleeting moment;”
but the Pyramids, and ruins of Karnac survive the Kaliffs and Cæsars,
the Ptolemies and Pharaohs, and countless monarchs and dynasties prior
even to them. Thus, whatever learned disputants may imagine as to
the primitive occupation of the valley of the Nile, the date of its
occupancy, and the race by whom it was first cultivated, we have in the
Pyramids incontestable proofs of a vast antiquity. Whatever historians
may say of the antiquity of ancient Rome, the _Cloaca Maxima_ of
Servius alone refutes the beautiful romance of Virgil--how Lavinius
and Turnus received Æneas ere Rome was; how Romulus and Remus founded
Rome, and were succeeded by seven kings, none of whom ever in reality
existed. But the existence of the _Cloaca Maxima_ and the researches
of the illustrious Niebuhr tell another tale more consonant with what
we know of man’s social and physical nature. In the most remote times,
man early adopted those measures of self-preservation which nature or
simple observation teaches him. History gives but little information
as to the measures adopted by ancient nations to secure public health;
and were it not for the remains of the _Cloaca Maxima_, so called, of
Servius Tullius, we should be as ignorant as Virgil assuredly was of
the ancient condition of Rome prior to the reign of the seven fabulous
kings.[58] Unquestionably the ancient race which preceded those grand
Romans who fill the page of history for nearly twenty centuries, had
discovered such means, and adopted measures for the safety of the
people. Authentic history, it is true, commenced with the Greeks and
Romans, and the history of Germany dates from Cæsar and Tacitus; but
the subjugation of the double-horned Rhine[59] must have commenced
long before “the building of the city.”[60] But the world as known to
the Romans, even during the reign of Trajan, was a contracted world
compared to what it is now. The tropical regions of the East, and
their vast populations, were wholly unknown to them; of Africa they
knew but little, of Asia still less, whilst the New World was as if
it existed not. Thus certain great problems in the history of mankind
were never presented to them, problems having a basis in facts which
men, for obvious reasons, are so unwilling to admit. The periplus of
the Mediterranean might almost be said to form the Roman world; beyond
the Rhine they made no conquests; the Danube formed their north-eastern
boundary; the eastern shores of the Black Sea were but rarely visited
by them; beyond the Euphrates and Tigris they, the Romans, never
gained a footing, whilst from tropical Africa they were entirely
excluded. Thus at no time were they called on to solve the problem as
to the possibility of European life maintaining its ground in tropical
regions; at no period were they called upon to give an opinion on
the momentous question which now agitates the world, the admission,
namely, of the primitive coloured races of men into the bosom of
civilized society.[61] “Wheresoever the Roman conquered, he inhabits;”
a just observation we owe to Seneca, confirmed by the history of that
wonderful people. As their conquests were confined to countries in
which the natives of Italy could at that time live and thrive, the
rapid extension of their empire, language, and forms of civilization,
need not be wondered at. Thus Rome successively became mistress of
many nations and races, but these were races with whom the Romans
could freely amalgamate; at no period of her history were they called
on to contend with the two great questions, the one social the other
physical, involved in the attempt to occupy by a white race a tropical
country, and a land inhabited by a purely savage race of coloured men;
the problems presented by modern history of a European race attempting
to hold India by the sword, to colonize the American world from the
Polar Sea to the Land of Fire, to inhabit, if not to cultivate, the
insalubrious Antilles, the banks of the Oronoco, or of the still more
dreadful Senegal, Gambia, and Niger, nowhere occur in Roman or Grecian
history; so that these are problems towards the solution of which
ancient history offers no assistance.

  [57] Gibbon.

  [58] Niebuhr.

  [59] Extremique hominum, Morini Rhenusque bicornis. _Æneid_ viii.

  [60] “Ab urbe condita;” from the building of the city (Rome), the era
  fixed on by the Romans.

  [61] This question was first agitated in the reign of Justinian, on
  the occasion of a proposal on his part to form a treaty with the
  negroes of Abyssinia. But the Abyssinians were not negroes.

A historian whose works I have already quoted on several occasions,
and who of all men had perhaps with most profit studied human nature,
has remarked that the aspiring genius of Rome sacrificed vanity to
ambition, deeming it more prudent to adopt virtue and merit for her
own wheresoever they were found, among slaves or strangers, enemies or
barbarians. This sacrifice it was easy for the Italian race to make;
naturally swarthy, and not unfrequently olive-coloured, they met with
no race with whom the Romans might not freely amalgamate. Far different
is it with modern Europe and her races; follow them to tropical India,
Africa, and America, and it will be seen that extinction seems the
sure result of all their efforts, whether they unite with the native
races or not. If they unite, their purer blood, as we may so call
it, soon disappears in the stream of a darker population; if they
spurn the union, climate, or as some would term it, malaria, speedily
exterminates their race and name.

In the first or second chapter of this Essay I ventured to suggest that
the discovery of the art to modify the earth, air, and waters of all
countries, so as to render them habitable for _all mankind_, was the
grand problem man is now called on to solve. In the construction of the
continents of the globe, nature seems to have had in view the formation
by centres of life of the living inhabitants of the globe. In these
centres she placed forms of life equal to sustain their existence,
occasionally aided, at other times unaided, by human industry. In the
virgin forests of America the aborigines lived and throve; under their
hands the earth underwent no modification; to the negro the deadly
regions of Central Africa are healthful and pleasant, though at times
abandoned to nature, at times deeply modified by human industry. India
and Java, the Malayan peninsula, as well as ancient Mexico and China,
were many of them highly cultivated regions, in which the aborigines
multiplied and enjoyed life; to the European they are premature graves.

But when it is attempted to transfer these centres of life to other
regions, the attempt has uniformly failed.

And yet the Romans, admitting that they never encountered a tropical
climate, seem to have colonized and thriven in countries in which the
natives of Western Europe cannot now maintain their ground, cannot
keep an army effective in the field for any length of time. The Roman
legions and citizens occupied the country of Numidia without an effort;
modern France, with an army larger than Rome ever had, can scarcely
maintain its position in Algeria. The young population are cut off in
their infancy, and it would seem that to maintain a Celtic race in
Algeria will test the energies of an empire which it is true formed but
a small province of imperial Rome. When we contrast late history with
the diffusion of Rome’s armies and citizens over the then known world,
we are forced to the conclusion, either that the Italian constitutions
of those days were stronger than those of the present inhabitants of
Europe, or that the form of civilization presented more safeguards for
the protection of health and life.

Nothing like the disasters of Varna and the Crimea seems ever to have
overtaken the Roman legions who guarded in the time of Trajan the
mouths of the Danube and the coasts of the Euxine, or restrained and
kept in check the barbarous Moors.

Amongst the arts practised by the ancients, but now lost, we must
include, I think, the knowledge of that discipline and practical
skill by which the Roman, Greek, and even Tartar generals, contrived
to keep their armies in the field in health and efficiency, whether
storming the castles of Jugurtha, or building walls of defence in that
land where English and French troops can neither fight nor march.[62]
Amongst the lost arts, still known it would seem to the Chinese, is
that of rendering salubrious the site of vast cities and camps. If I am
right in the principles I have endeavoured to establish throughout this
Essay, this art must have been based on the practical knowledge that,
generally speaking, the earth, as framed by nature, is not usually
an unhealthy _habitat_ for those races which grow up in her centres
of created life, and it is only when man interferes, and interferes
imperfectly, that the air and waters become pestilential to him. The
secret lies, no doubt, in agriculture, that first of human arts--that
art by which civilization exists. That human life is of as much value
by the banks of the Meuse, the Scheldt, and the Rhine, as in Sussex or
Surrey, is due to the industry of the inhabitants of Brabant and the
islands of the Rhine. On man in a great measure depends the position
which life is to hold in the scale of fate; he may raise it to its
maximum or sink it to zero. Centuries, it is true, may elapse before
human industry can render the banks of the Senegal, the Maranon, or the
Zambeze, a fit abode for civilized European man, but if the European
persist in transporting himself to these haunts, he must discover
the means to do so in safety, or perish in the attempt. Nature did
not make these countries for him, but she gave him reason, judgment,
observation, and the power of generalization, on the right use of
which faculties his safety must ever depend. The celebrated Jefferson
apologizes in one his confidential dispatches to his government for
noticing various political movements in countries seemingly remote
from and devoid of all interest to a citizen of the United States of
America, by remarking, that although such matters seem remote and
foreign to the object of his duties, they may yet at no distant period
swell into relations of sufficient magnitude to shake the world. As in
the political, so in the moral world; whether the empire of the Sultans
stand or fall, may be a matter of little import to an inhabitant of
Western Europe, nor need it distress him that the finest countries in
the world are nearly reduced to deserts under the administration of
the odious Turcoman. But it may be useful to him to be on his guard as
to the condition of countries through which the spirit of commerce now
urges the Western nations. Many of these countries do not improve; to
compare them with what they were in the days of Trajan were merely a
mockery; the low lands of the delta of the Danube are simply foci of
fever and pestilence, and are likely to continue so under their present

  [62] Trajan’s wall, between the Danube and the Euxine, at Kostenjie.

All history points to the East and to Africa as the seat and source of
plague, and the entanglement of Eastern affairs presses more and more
on the European nations; if we may trust the statistics of commerce,
Western Europe at times draws a large portion of her subsistence from
countries of which we know but little. On this I make no remark, my
object being merely to show that, however distant these lands lie,
their malarious condition has an influence over the European family of
nations, an influence which daily increases socially, and which, though
originating in the obscure and unknown East, has shown itself at times
at Rome and Moscow, London and Paris, in characters compared to which
all other evils appear insignificant.

All that lives or has lived is doomed to die, to waste away, and to
disappear; as it perishes it is consumed by nature’s processes, in such
a manner as to entail no danger to the living world, unless civilized
man interferes. For civilized man she has made no provision, saving the
bestowing on him a soil more or less fertile, a constitution more or
less equal to toil, a reasoning power, which in things practical must
not be measured by the loftiness of his conceptions and generalizations.

Whenever and wheresoever he congregates into masses, there “the earth,
the air, and the waters,” receive modifications from him, which, when
injurious, he alone can rectify. The most consolatory view which man
can take of such a condition of things is unquestionably to believe
them to a great extent remediable by his own labour and intelligence;
for even should he fail, there remains to him the consolation that he
has done his best.



It is easier to pull down than to build up; easier to refute than to
convince; easier to find fault than to suggest a remedy: and this
reflection may occur, and no doubt has occurred, to those, be they few
or many, who have perused the preceding chapters of this work. It may
now be asked of me explicitly, What is your theory? What is your remedy
for the evils complained of? To this I might reply, as the immortal
historian of the “Decline and Fall” is said to have done, “If you have
read certain chapters of my work with sufficient attention, you may
extract from them my meaning and my views;” but as this might imply on
my part either a Teutonic love for obscurity in phraseology, or a fear
to commit myself to any theory, I shall here sum up in a few words the
views I have arrived at after much reflection on the matter, during a
long and active life passed in a country supposed to be a hotbed of
malaria, the great source indeed of malaria in Western Europe, that
land for which nature has done so little and man so much.

1. There floats in the lower strata of the atmosphere in all regions
of the earth, but in very various proportions, for reasons already
explained, a poison or poisons, generated by the processes which nature
adopts for the destruction of past generations, and the reconstruction
of those to come; the destruction of the aged, the worn-out, the nearly
extinguished; the reconstruction of the organisms springing into life,
to occupy the place of those that were! Whether the poison be one or
many; whether it be a single species or one of a natural family, does
not affect the general conclusions. The diversity of its effects is no
proof of diversity in its essential nature or even origin; the living
principle is supposed to be of one nature everywhere and for ever;
yet see how varied are the results of this principle in moulding the
vegetable and animal worlds; how slight are the modifications even in
organic elements, which, when called into play, give rise to the most
astonishing and unexpected diversity of results. Why should it not
happen, then, with the poison, influence, or thing we call malaria,
which, modified by a chemical action too subtle for the scientific man
to observe, may yet, being so modified, give rise to an intermittent
or a remittent, a plague, a cholera, a diphtherite, a scarlatina, a
typhus, or a small-pox? Where did so many poisons come from? Whence
came the murrains, the vine-plague, the potato-destroying poison, which
was not at all new, neither was it confined to the potato? Whence came
the pestilences which destroyed the ancient world? which exterminated
at once whole species and genera now extinct? Of one thing we may be
assured, they did not die a natural death.

2. This poison, whatever it may be, floats in the lower regions of the
atmosphere, supported therein by the gaseous products of fermentation,
and more especially by the ammonia now proved to exist everywhere in
the atmosphere. It is the product, in fact, of the slow combustion
perpetually going on in the air, the earth, the waters, wherever, in
fact, animal or vegetable organisms are to be decomposed. We call it
putrefaction; it is in truth a _ferment_, and the fermentable matter,
that which gives rise to the ferment, is the immediate agent as well
as the result (for it is the nature of all ferments to reproduce their
process) of this fermentation, accumulated in the lower regions of the
atmosphere. Increased to the dangerous point by men’s imprudence or
ignorance, quickened by epidemic influences with whose nature we are
of course wholly unacquainted, and absorbed by the living tissues, it
excites that fermentation, that tendency to putrescence in the living
blood to whose results medical men have given so many appellations. At
times it is called ague; at times remittent fever; now it is small-pox;
and now a fatal diphtherite. To the transit of _ferments_ through the
air and to their inhalation by man, I ascribe the diseases usually
called zymotic. In ancient primitive times, when physicians were
rare,[63] and men did not interfere, a poison thus absorbed ran its
course from incubation to specific fermentation, with all its results,
in a given time, terminating in a crisis which might be calculated
and determined; and which might prove fatal or at once remove the
disease. A violent perspiration, a severe diarrhœa, a specific and
contagious eruption on the surface of the body, proved and effected
the elimination of the poison from the system. The ferment had done
its work; it had altered the mass of the blood, and the products of
the slow combustion (_putrescence_, rottenness, _fermentation_) were
discharged by the secretions, according to circumstances peculiar
to the constitution of the individual: as out of the same materials
serpents elaborate poisons of very different powers and qualities, so
the _ferment_, passing through various constitutions, gives rise to
various results. It pervades the air and clings to it, nor can it be
avoided but by a change of place of residence;[64] storms may, and no
doubt do, affect it, but they frequently fail in dislodging the poison;
intervening wide-spread oceans fail to interrupt its course;[65] and as
regards the caprice exhibited in its attacks, we have only to reflect
on the number of elements, vital, atmospheric, social, and chemical,
involved in its full maturescence. Our doubts on all such matters
originate probably in the coarse chemical theories and still coarser
chemical experiments which prevailed about thirty years ago, and from
their influence, from which men’s minds have not as yet escaped. The
atmosphere was declared to contain a few wide-spread gaseous elements,
and to be unalterable; the air of towns, of theatres, of large heated
apartments, crowded with people, was boldly asserted by chemists still
alive to be eudiometrically perfect.

  [63] There were no medical men in Rome for the first five centuries
  of her great career; and some have fancied that this fact explains
  the astonishing number of armies which the republic found no
  difficulty in sending into the field.

  [64] When unassisted by other deleterious influences, the poison,
  though all but universal over the locality, may not be destructive.
  After the draining the Lake of Haarlem, the principal physician of
  the district informed me that in 2000 cases of ague he had not lost a

  [65] The choleraic ferment traversed in ships, no doubt, the
  Atlantic, as typhus had often done before; but there are grounds for
  believing that vegetable and animal matters in a state of rottenness
  (fermentation), floating about in the air, are not unfrequently
  transported to great and almost incredible distances. Ehrenberg and
  Humboldt have particularly insisted on this fact, and have spoken of
  distances traversed by these fermentable elements, which I hesitate
  to quote from memory. Assuredly they were very great, extending to
  some hundred miles from the seat of their origin.

§ 1. _Discovery of foreign bodies, the remains of animal and vegetable
life, and therefore_ FERMENTABLE, _in the air floating over canals,
ditches, marshes, &c._--Scientific chemists, as well as the professors
of the conjectural art, are occasionally behind the knowledge of
the careful, observing, unprejudiced practical men of the day.[66]
Experience taught me, whilst engaged in other inquiries, that the
sulphuretted hydrogen gas arising from the waters of the canals of
Holland is quite sufficient to spoil cottons printed with nitrate of
lead, used for dyeing yellow with the chromate of potass. The waters
of these canals hold this gas in solution in a certain sense, but from
May to September inclusive, the gas escapes during the night in great

  [66] England has often paid a high price for the first steps in
  science. Mr. Papillion, in 1806, received from Government 10,000_l._
  for the introduction of dyeing Turkey red; and his success was owing
  to his knowledge of the water proper for the operation, which must be
  void of fermentable bodies.

At this time vapours arising from the waters and floating over the
adjoining grounds, were found to contain minute portions of aquatic
plants mingled with the spores of fungi in vast abundance, together
with fragments of a membranous and gelatinous substance about to be
mentioned. To these must be added the remains of infusoria not to be
detected in dried specimens.

The injurious effects of water holding such substances, gaseous and
solid, in solution, we overcome by boiling and passing the steam
through (heated) iron pipes, and re-converting the steam into water.
By this process we get rid of the injurious effects of these foreign
matters, gaseous and solid, held in a kind of solution by the water, in
as far, at least, as they affect the colours used in dyeing.

During these examinations of the waters themselves, it was distinctly
observed that the infusoria and testaceous mollusca, microscopic and
otherwise, with which such waters abound, were developed in glutinous
membranes attached to the aquatic herbs abounding in these waters;
in short, these membranes seem to be the matrix for the growth,
nourishment, and production (using the term in a limited sense) of
these organized beings; they form an essential condition of their

The plants themselves were now washed in distilled water, and the
animal products were the semivalve and bivalve shells of which I
have preserved many specimens. The semivalve belong to the natural
families Buccinum, Lynceus, Helix, and Planorbis; the bivalve to the
Cardiacæ. The semivalves are the most abundant. By filtering the water
which remained after the shells had been removed, innumerable minute
particles like dust were discovered; these particles were ascertained
by the aid of the microscope to be mainly composed of minute fragments
of aquatic plants and of the spores of fungi; to these must, no doubt,
be added, although not visible when dried, the remains of zoophytes,
and of the glutinous membranes forming the matrix of animal aquatic

I now endeavoured to obtain the glutinous membrane or matrix in which
these testaceous mollusca were obviously developed, apart and distinct
from the animals themselves. To attain this desirable point we filled
a glass receiver with water containing the aquatic plants and shells,
and the gelatinous membrane already spoken of. The receiver was now
inverted upon a plate, and water poured into the plate to the depth of
half an inch.

In a few days the receiver became filled with gas, forcing the water
downwards into the plate on which the receiver rested; and although
after the first day we could not discover any of the gelatinous
membranes in the lower part of the receiver, yet that in the plate
became like a flaky jelly, attaching itself to blades of grass or
leaves. The surface exposed to the atmosphere became dry and brittle,
and in this state resembled thin layers of gum; the substance thus
desiccated strongly resembled jelly.

The glutinous membrane of which frequent mention has been made above,
is of a very viscid nature, and when combined with any animal substance
in a state of transition or fermentation, it is poisonous. It is, I
believe, generally viewed as the matrix for the development of the ova
of these shell fish, and considered as a product or secretion of the
parent. Into this question I enter not, leaving it, if it be one, to

On exposing for a few days some of the larger testaceous mollusca
alive to the atmosphere of the room at a temperature varying from
65° to 70° Fahr., strong proofs were obtained that ammonia was
produced in the interior of the shell confined therein by the membrane
called operculum, sealing, as it were, the aperture into the shell
hermetically. On puncturing this membrane the presence of ammoniacal
gas could be distinctly traced by the odour.

I submit to the consideration of professed physiologists the following
questions:--1st. What are the effects likely to result to man from
the inhalation of these microscopic and gaseous products in a state
of decomposition, they being certainly present in the vapours arising
from the waters of canals, ditches, &c., in many countries, especially
during the nights of spring, summer, and autumn? 2nd. What are the evil
effects likely to arise to man from the use of such waters as drink,
or when employed for culinary purposes? Lastly: As the gelatinous
membranes alluded to are the nidus of various forms of organic life,
and contain those forms, developed and undeveloped, occasionally in a
state of decomposition, to which of the two forms of life, animal or
vegetable, or to both, is to be ascribed the deleterious effects on
man, and ascribed by physicians to an unknown poison called Malaria,
designated by them as “a poison, an influence, a miasm, a thing
unknown”? Ferments and putrescence are not “things unknown:” let us
adhere to facts.

§ 2. Thus the principle of wasting away by the action of the
atmosphere, of the rotting of vegetable and animal substances, first
developed by the illustrious Liebig, opened up to me the path to
that theory which seems to reconcile the conflicting observations of
pathologists,--that vegetable and animal matters do ferment or rot, and
that in this state of rottenness they are carried through the air, was
with me no longer a matter of doubt; next came the question, as to the
effects of such matters on man when inhaled by respiration and conveyed
directly into the living, circulating blood, that most complex of all
fluids, that mysterious compound out of which nature constructs the
animal world.

This slow wasting takes place in any damp place under ground, and
the ferments assume the form of vapour when such places happen to be
warmer than the open air; it is in this state that the odour is so
sensible to us after a hot dry day or during cold nights. There is no
smell in rainy or damp weather. It is in the spring and autumn months
when ferments from slow combustion abound, aided by the amount of heat
and moisture which then prevail, and by the floating of plants. The
poison thus generated is known to be the product of a ferment, and
like many such products, possesses the quality of fermenting other
organic compounds with which it may come in contact. Introduced into
the living system of man, it finds in certain individuals the material
already disposed to pass into fermentation. It incubates, and this
incubation is measured as to time by a variety of circumstances I need
not enumerate. In cold countries the incubation is slow, extending over
many months; not that the ferment differs, but its action is modified
by the existing condition of the accessories to its action and power.
The ferment introduced into the blood in autumn may not show its full
action on the living fluids until the following spring, or early in
summer: in hot countries it is different; there the ferment, aided by
numerous adjuncts, acts almost immediately; fever sets in, causing
violent reaction of the conservative powers of nature; delirium,
coma, vomiting, death. The mass of the blood has undergone a change
in all its constituents, and dissolution and putrefaction are swift
in reducing the frame, even whilst life is still present, to that
state to which all that lives must come at last; whilst the physician
loses himself in vague theories of an “unknown poison”--a malaria, a
something not strictly a gas, a matter or influence differing from all
chemical or other agents known, the scientific chemist steps in, and
shows that the subtle matter they so anxiously endeavour to discover,
is a process constantly going on before their eyes; a chemical process,
universal; the process, in short, on which in a great measure depends
the disposal of the dead and effete remains of the organic world; the
growth, the nourishment, the renovator of each successive generation of
the same world.

§ 3. It may be now fully admitted that ammonia is the active principle
or stimulus to vegetable life, as shown by the extraordinary growth
of plants in warm damp climates; in these malaria--as we may still
call the poison so developed--exists to the greatest extent, as in the
Pontine Marshes, by the banks of the Po, Ferrara and Bologna. From
various experiments and observations, I have been led to the conclusion
that the ammonia constantly present in the atmosphere, and derived
from several sources,[67] is the chief cause of the activity which the
ferment, or poison, displays under different and varying circumstances.
There prevails, in truth, an excess of ammonia in such an atmosphere,
resulting from the nitrogen uniting with hydrogen; from the
decomposition of vegetable matter carrying decayed animal matter along
with it; and from the ammonia always existing in the spawn and in the
matter of the shells of infusoria. All my researches into the effects
which the various gases have upon animal tissues, showed ammonia
to be the most destructive; in fact, no animal tissue can resist
complete decomposition by caustic ammonia. I conclude, therefore, that
vegetable and animal matter in a state of fermentation, and mixed
with ammonia, is the cause or essence of that destructive power which
physicians ascribe to malaria. Should this fermentable matter pass in
a concentrated state into the torrent of the circulation, the globules
of the blood are destroyed, and become black; the person is in the
cold stage of fever; next, the vegetable matter ferments, causing the
hot stage. No one in Holland has any doubt as to the origin of this
power, but ascribes it uniformly to the draining of some lake; and it
amounts almost to a demonstration that the air under such circumstances
is poisonous or injurious to health. It was even foretold by several
writers that fevers would result from draining the lake of Haarlem, as
took place in the years 1608, 1641, 1727, 1779, from draining various

  [67] The ammonia always present in the atmosphere is probably derived
  chiefly from the union of nitrogen and hydrogen; but much of it also
  no doubt has its source in the fermentation of animal and vegetable

  [68] Baron von Lynden.

If the principles I have announced be correct, the extreme
impropriety--not to use a stronger phrase--of carrying on excavations
or other extensive works on the muddy banks of rivers, in marshy or
swampy forests, during the summer months, must be obvious to all
reflecting persons. No work should be done in such places, or in ponds,
after the month of April, for it is warm dry weather that sets malaria
afloat. But if this ferment--which we may strictly call malaria, as
producing a malarious condition of the air--be, as I apprehend it is,
the cause of fever, why should not medical men direct their attention
more earnestly to the question in how far such a fermentation of the
blood may be met by the employment of substances known to resist and
counteract fermentation? Are physicians agreed on the nature of fevers,
and the best means of curing them?[69]

  [69] I have known many persons sickly from the effects of
  intermitting fever or malaria from a residence in warm climates,
  and who have suffered and perished from an injudicious treatment.
  Ill-formed or incomplete agues are extremely common, even in the
  south of England, in London especially. They show themselves under a
  variety of forms, and with much severity, in the cases of those who,
  having once visited a true malarious climate, are ever afterwards
  more or less liable to a return of the disease. Let men reflect;
  simple truths travel slowly, yet are truths notwithstanding. The
  death of the well-known M. Soyer was evidently caused by his wholly
  misunderstanding the nature of his complaint, which, in fact, was a
  fever originally caught in the Crimea.

Nothing can be more interesting, in a natural history point of view,
than to watch the results upon large bodies of water, of attempts,
more or less successful, to complete their drainage. Thus during the
operations carried on for this purpose at Haarlem, there sprung up in
the dry places of the more elevated parts an extraordinary quantity
of plants and herbs, which were not seen in the country before they
flowered and sent millions of seeds with their diminutive rocket,
silky tails into the air. They were too minute to be seen upon grass,
but the footpaths were covered with them, and a current of wind might
carry them to distant regions, as the sand is carried from the coast of
Africa into the track of the Brazilian packets, to such an extent as to
make it uncomfortable to walk on deck. It is by no means, therefore,
improbable that those errant seeds came from a foreign land, the native
produce of other countries. Continuing my observations into the transit
of seeds, I have found them to be the cause of shallow canals in
England being full of heretofore unknown water-plants, to the extent of
impeding navigation.

It is mentioned in the “Kosmos” of Humboldt, that the dust resulting
from eruptions of the volcanic mountains in South America was observed
in Spain. But if currents of wind thus carry seeds and other matters
hundreds of miles through the air, no one can be surprised that the
aquatic plants above alluded to floated to England through the air,
from Holland; these plants, new to the land of their accidental
adoption, bring with them a new corresponding animal life; in due time
they come to maturity and die, and now Nature steps in to take up the
task, and complete her work; her process is simple in appearance,
most complex in its results: a malarious air--malarious at least to
man--appears, as it may be, for the first time in the district,
ascribed by medical men to every cause but the true one. In their
anxiety to discover a cause, they fix on some antiquated drain, or
cesspool, or ditch, by the margins of which many generations of a
stout peasantry had lived and died; or they dive into the pump-well,
and triumphantly exhibit infusoria, not unlikely engaged at the very
moment in purifying the water: it never seems to have occurred to them
that _ferments_ only appear in certain combinations of the air--under
circumstances which only occasionally occur, and that (which is most
lamentable to think of, as in the case of London and the Thames) the
evil is most frequently of man’s creation.[70]

  [70] A friend who resided long on the Grotevisch Rivière, and in het
  land den Caffre, informs me that if the Zuureveld be ploughed up, or
  altered by the burning, for example, of a Caffre hut, the sour grass,
  whence the district derives its name, disappears, and sweet herbage
  of various kinds take its place. None of these exist naturally in the
  district, so that the seeds must come from great distances.

The operations of nature when left to herself never vary; they may
always be calculated on, foretold, anticipated; on this assured and
irrefutable fact all science rests. It is only when man interferes and
modifies the elements at work that nature seems to alter her processes;
a disturbing agent has been thrust into the machinery, and the mischief
it effects must either be counteracted or entirely overcome. So long
as the Lake of Haarlem was a lake, or mere, so long were its banks
healthy; but drain it partially, and you must be prepared for the
result. There is no middle course; that which was once a lake or sea
cannot be left in the condition of a putrid, imperfectly-drained,
fermenting mass of mud, teeming with animal and vegetable life, and
with a material for which oxygen is the natural ferment; it must be
arrested by the hands which drained, or attempted to drain it, and
converted into a healthy pasture-land or a wheat-field; if left to
nature, centuries might elapse before that which was once a sea would
become a healthy forest or natural meadow, during which period man,
should he persist in residing on its banks, must undergo the penalty of
his own want of knowledge.[71]

  [71] The effects of partial and incomplete drainage have ever been
  the same. In 1823, when the new Polder was made at Neusen-on-the
  Sheldt, small-pox raged in the neighbouring villages to such an
  extent that the children were forbidden to attend school. The effects
  are to be seen now in persons over sixty years of age, bearing the
  marks of the epidemic. The whole atmosphere of the district was


In the first chapters of this work I have endeavoured to trace briefly
yet succinctly the history of opinion as to the nature of malaria,
showing how, prior to the appearance of Macculloch, no one had given
to the theory of malaria any definite form. In those which followed I
have traced the history of his presumed discovery from the period of
its first announcement to its distinct refutation by one of the ablest
of statisticians, showing that, notwithstanding this refutation, the
physician having, in fact, no other theory to fall back on, persisted
in adopting the theory, and, as a natural result, continued to look
for and to find in cesspools and ditches, lay-stalls and drains, that
unknown and mysterious poison which they had been told by Macculloch
was the cause of all diseases. Confounding it with bad odours of all
sorts, they sought for remedies in the destruction of bad odours; at
times they sealed the sewers and cesspools hermetically and by law:
now they opened up and ventilated the sewers and cesspools also by
law;[72] and lastly, on finding that they had poisoned the air of the
metropolis, and that every experiment they made ended in the precisely
opposite results to what they had foretold would happen, as a last
resource they endeavour now so to dilute the refuse of living beings
as to render it, if possible, inodorous at least. This experiment will
also fail. Like true Englishmen, they would not let well alone; they
would attempt to solve questions by main force, which science, aided
by long and careful experience and observation, could alone effect.
At last Liebig appeared, and gave to the whole question a new phasis
and another basis; that basis rests on an appeal to the great laws
of nature, and not on any researches into the occult, hidden, and
mysterious laws regulating the building up and the constructing of the
various forms of animal and vegetable life. In this grand work the
vital force is in action, whereas the destructive processes by which
she annihilates her own forms are strictly chemical; there science may
be properly said to commence in respect of the great question I now
consider; and uniting experience with observation, it seems to lead to
the following conclusions, which, if legitimate, will probably stand
their ground until overthrown or modified by the larger experience of
succeeding ages.

  [72] _Law_ being no body, and quite irresponsible, the blame of these
  cruel experiments on the health of the population cannot readily be
  brought home to any one.

§ 1. Seeing that _putrescent_, that is _fermentable_, bodies can and
do exert so great an influence on organic compounds when dead (in the
sense we consider them), it is not unreasonable to suppose that animal
structures and fluids capable of being fermented, may undergo the same
process, that is, fermentation, putrescence, and destruction, or decay,
whilst forming a part of the living body.

§ 2. As no sane person doubts the harmony which can be shown to exist
in all created beings, so it is probable, if not quite certain,
that the laws of decomposition must be as regular as the laws of
composition; or, in other words, that as the organic matter is without
a doubt the same throughout the living world, and as living bodies are
built up or constructed agreeably to certain laws, so, undoubtedly,
will they be decomposed by laws equally fixed and constant; invariable;
and the nature of the material so decomposed will in no shape be
affected by those specific differences which bestow on organic nature
her beauteous and varied aspect.

§ 3. The final product, whether of composition or decomposition, must
be the same in all respectively; the infusoria, as well as the gigantic
whale and elephant, are composed, when living, of the same elementary
tissues, and, when dead, decompose into elements the same in all.

§ 4. The presence of microscopic animalcules in putrifying substances
is viewed by Liebig as accidental, and not essential to putrefaction
or to fermentation; but even admitting this, it is certain that
animalcules (infusoria) exist everywhere in inconceivable numbers;
if water contains these putrescible substances, as it must always
do, then the infusoria are also present in the water; let this water
evaporate under the heat of the sun, and we have in a fermentable,
that is, putrescible, condition countless myriads of infusoria wafted
through the atmosphere, and in certain localities (Pontine Marshes,
Sierra Leone, the Orinoco, &c.) forming almost a constant, if not a
constituent, part of the atmosphere; they pass into living bodies by
respiration: hence the hitherto inexplicable phenomena with regard to
the influence of locality in the production of disease, whether derived
from animal or vegetable remains.

§ 5. Thus these bodies cause disease, not as live matter, but as dead,
fermentable, and putrescible. They are not found everywhere, nor are
they everywhere liable to pass into fermentation, a certain degree
of heat being necessary for the production of this condition. Their
evil effects on human life are chiefly felt when man places himself in
a false position in regard to them. In pursuit of gain, national or
individual, he seeks the deltas of the rivers of hot climates, plunges
within the tropics, despising the maxims of the natives of those
countries, encamps on or near putrescent marshes, hoping to escape
destruction; prances in holiday costume across the Dobrudscha, as if
he were on the Champs Elysées or the grassy slopes of Hyde Park, and
having carried folly and contempt for the experience of others to its
height, pays the sad penalty sure to be exacted by nature from all
those who despise her warnings.

These are my opinions, supported, I believe, by facts and figures, and
to those who honour me with a perusal of the preceding chapters I beg
leave to say, in the words of the ancient poet and satirist--

          Si quid novisti rectius istis,
  Candidus imperti, si non--his utere mecum.


To avoid overloading the text, I have thrown into the form of an
Appendix several Notes more or less intimately connected with the great
question considered in the body of the work. They may be read with or
without any reference to the various headings they treat of.


By the deodorizing processes now in use, the ammonia, the most valuable
constituent of manures, is destroyed; whilst by the flushing of sewers
with an excessive quantity of water it is dissipated; hence the low
value, or rather the absolute inutility of the sewage of large towns,
as manure, when diluted with the surface drainage and other waters,
excepting in the case of reclaiming waste lands, in order to convert
them into meadows of so highly objectionable a character that no one
can or will reside near them. The smell from such meadows is most

Even in such cases an outfall must be provided for the surplus sewage
waters, either into a river or into the sea, for the meadows to be
irrigated require but little of it, and that only occasionally and
during droughts.

The fixing the ammonia is the great difficulty the agriculturist
experiences in all questions respecting those manures which naturally
contain or produce it. Its volatility is so great that it not only
readily escapes into the air, but carries along with it, especially
from waters, bodies at the moment in a state of slow combustion; or,
in other words, ferments, capable of exciting fermentation in other
fermentable bodies.

It may even pass into the condition of caustic ammonia.[73]

  [73] It is to be remarked that the specific gravity of ammoniacal gas
  is 53·619; can it be wondered at that this gas should carry bodies
  from waters which are in a state of slow combustion; during its
  transit through the air it may even become caustic ammonia?

In a well written pamphlet by Mr. Ward,[74] the unhappy and fatal
mistake of mixing the surface drainage with the sewage of London is
clearly pointed out for the hundredth time, but the parties who planned
the scheme will no more take notice of such facts than they did fifteen
or twenty years ago, when they commenced their work of polluting the
Thames and other rivers.

  [74] _Purification of the Thames_. A Letter by F. O. Ward, Esq.,
  addressed to William Coningham, Esq., M.P. London: Renshaw, Strand.

To Mr. Ward’s proposal of purifying the river and fertilizing the land
by tubular drainage, there are, however, many serious objections.

NOTE 2.--_Habits of the_ WILDE, _in desert or uninhabited countries._

It is known to sportsmen that in the neighbourhood of hills, partridges
leave the low grounds at the approach of evening, and take themselves
to the hilly or more elevated district. Nature has taught them a very
curious fact in meteorology, namely, that on leaving the valley at
night, and ascending the hill, the temperature of the air increases
up to a certain elevation, and from that point upwards decreases. The
game ascends to the point of highest temperature, and there remains for
the evening. A friend informs me that whilst crossing the high range
of mountains forming the watershed between the Grotevisch Rivière and
the Zondag Rivière, in Southern Africa, he experienced as he ascended
intense cold, with heavy dews in the valleys through which ran the
sources of the Grotevisch Rivière, and these continued until he reached
the base of the crowning heights. Here the party slept in a mud-hut
belonging to a Dutch boer. During the ascent they saw no game; but on
climbing about half way up the remaining steep before daybreak next
morning, they reached a spot where all the large game had congregated.
It was the point of greatest warmth, generally a few hundred feet above
the plain, and below the summit of the mountain. From this point to the
summit the cold was most intense, and snow lay on the high peaks of the

When the shells of infusoria are driven about in the atmosphere
they lose their carbonate of lime by the acid fermentation; and the
membranous portions having the properties of coagulated albumen,
and being also fermentable, may, by passing into the blood, become
excitants of fermentation. This has been already fully explained in the

  [75] It is mentioned in the Report on the Wine Disease in Portugal,
  that the _oidium_ was first discovered at Margate; if this was the
  case, might it not have originated from the phosphorescent beings in
  sea water, observed by all travellers in the evening on the coasts
  of Flanders, and known in Holland as Zee Vlam? The potato disease is
  thought by some to have sprung from the same cause.

NOTE 3.--_Moss._

In the _Annales de Chimie_, volume xxix. p. 225, mention is made that
the walls of various towns which had been under water for several
years having become exposed, from the effects of a dry summer and
hot weather, became covered with vegetable matter, the decomposition
of which infected the atmosphere, and caused great sickness in the
environs, and particularly where buildings were situated in marshes in
communication with the sea. The vegetation, in fact, was composed of

On a recent visit to Bangor, in North Wales, I was struck with the nice
firm turf which was in the garden; and upon inquiring of the gardener,
he informed me that the turf came from the seeds blown from the hills,
and that it required great care on the part of the farmers to keep
it under, or it would be exceedingly injurious to land and buildings
if neglected. When it grows on walls it splits them by the capillary
expansion of its roots between the bricks operated upon by damp hot
weather. I have seen this lichen destroy the pillars of a gateway three
feet thick.

Mill-stones are made in Germany out of granite, by means of willow pegs
being driven into holes thinly covered with water; this causes the
willow to act by capillary expansion, forcing the mill-stones of the
required size out of the rock.

It is of the utmost importance that the nature of moss and lichen
generally should be well studied before constructing sewers, &c., where
vegetable matter exists near water.

Was it by similar means that the ancient Egyptians and inhabitants of
Arabia Petræa cut from the solid rock those vast blocks, in effecting
which they do not seem to have availed themselves of any modern
mechanical contrivances?

The _ferment_, that is, the substances in a state of fermentation
and capable of acting on all fermentable bodies, and especially on
complex organic compounds, as the blood, exist at all times in the
air, but are as a matter of course greatly influenced by a variety of
circumstances as regards their effects on man and other animals. It is
proved by indubitable evidence that this morbific matter is as capable
of entering the system when minute particles of it are diffused in the
atmosphere as when it is directly introduced into the blood vessels by
a wound. When diffused in the air, these noxious particles are conveyed
into the system through the thin and delicate walls of the air-vesicles
of the lungs in the act of respiration. The mode in which the
air-vesicles are formed and disposed is such as to give to the human
lungs an almost incredible extent of absorbing surface, while at every
point of this surface there is a vascular tube ready to receive any
substance imbibed by it and to carry it at once into the current of the
circulation. Thus in certain seasons boils and carbuncles prevail to an
alarming extent, and surgeons dare not operate lest they should lose
their patients from erysipelas and inflammations, running rapidly into
putrescence. In large hospitals the poisonous air in all probability is
constantly present, attacking those who have been previously weakened
by disease or wounds, or loss of blood; in other words, all those in
whom from any circumstance (as by the depression of the vital powers)
the complex organic compounds are held loosely together, and are
therefore prepared to ferment or to fall into putrescence.

NOTE 4.--_Anther._

This name is given in botany to the summit or top of the stamen
containing the fertilizing fruit-producing dust.

Pollen is the fecundating dust or fine substance, like flour, meal, or
fine bran.

Farina, contained in the anther of flowers and plants, which is
dispersed on their stigma for impregnation, form a vegetable essence
constituting the particular nature of a substance forming the flower
existing in other plants of the same family or kind.

Spore or sporule in botany is that product of flowerless plants which
performs the function of seeds.

These substances float in the atmosphere, and are the cause of the hay
fever; and when they fall into water and are afterwards left upon mud
they ferment, and being dried up by the sun they fly about with the
spawn of animals.

Should seeds fly about with the pollen or farina in a state of decay
and full of carbonic acid, the oxygen of the atmosphere, so essential
to human beings, is diminished, and the pollen or seeds are inhaled
into the lungs, and are thus exposed to the action of oxygen whilst
circulating with the blood.

The result of an excess of carbon in the air is the growth of ferns on
barren rocks, which ferns subsequently become coal.

The same cause will always produce the same results. When vegetable
matters rise from a large surface of earth or mud (as from the
newly-drained forty thousand acres of the lake of Haarlem), there are
no plants there to inhale the carbonic acid, and to give out oxygen;
but those seeds being rotten or in a state of ferment, the oxygen
for the decomposition is drawn from the atmosphere alone, and human
beings who breathe this malaria have fever; the atmosphere is tainted:
miasms of carbon with hydrogen gas (the lightest thing known) fly
about, carrying them to points where sulphurous gases may find them
a resting-place on mud and shallow waters: these give rise to fever,
cholera, plague, and to all zymotic diseases.

NOTE 5.--_Algæ, or Sea-weeds of the Mediterranean Sea._

These were examined by Doctor Derbes, Professor of Sciences, and
Captain Solier, of Marseilles, and the result of their researches was
published in the supplement of the _Comtes Rendus_ of the Académie des
Sciences, in answer to a prize essay proposed by the Academy in 1847.
Nothing can exceed the botanical truthfulness of the memoir presented
by these gentlemen to the Academy. After a careful examination of the
substances resulting from the mass of decayed sea-weed in the delta
of the various rivers which flow into the Mediterranean Sea, they
arrived at the conclusion that the product is the cause of fevers, by
generating a malaria which the vital powers are unequal to meet. Thus
the cholera existed at Marseilles in 1850; all knowledge of the extent
of its destructive ravages was withheld from the public; and the truth
of this is in some measure proved by the readiness with which the Board
of Health recommend the quarantine of ten to fifteen days, when it was
reported that the plague or cholera existed at Tripoli, Sicily, and
Sardinia.--July, 1858.

NOTE 6.--_The Marseilles Board of Health and Quarantine._



Sir,--The Board of Health of Marseilles are about to establish
quarantine regulations of ten days’ and fifteen days’ duration at
that port, because “a dreadful plague rages at Bengazzi, in Tripoli,
and is extending along the coast to Alexandria.” Individuals are to
be confined ten days, and in certain cases fifteen days. Letters are
to be purified, &c., and some 1500 Piedmontese labourers are likely
to be disturbed and thrown out of work if the proposed quarantine
regulations are established. And so this is the sum total of sanitary
experience for the last ten years! The French authorities saw all
quarantine regulations broken down during the Crimean war; in fact,
joined the British in abolishing a quarantine at Smyrna, at Galipoli,
at Constantinople, at Sinope, at Samsoon, at Trebizonde, at Malta, and
even at Marseilles, and indeed at all other ports and places used by
the transports and by the armies in alliance.

The armies certainly did not escape fever and cholera in their most
terrible forms. The French, the British, and the Sardinians alike
suffered, both in the field and in hospital, at the commencement. The
British alone, however, by means of sanitary works and regulations,
reduced cholera attacks to a _minimum_, and almost abolished fever. A
few simple alterations to the sewers from the great hospitals on the
Bosphorus and other places; ventilation--in many instances by simply
breaking the top squares of windows; regular scavenging without and
cleansing within the works of the hospitals, and the regular use of
the lime-wash brush, emptied the hospital wards of fever patients.
Surface cleansing at Balaklava, and regular scavenging both the shores
and water of the harbour; covering the shallow graves with gravel
and earth; scavenging the camp, and daily disinfecting all latrines,
soon reduced the British army mortality below home or barrack life
and service. The French neglected these things, or blundered in their
execution, as the 5000 deaths per month in the hospitals on the
Bosphorus, from hospital and camp fever alone, during the last three
months of the war, testify. That certain diseases are contagious,
such as scarlatina, measles, small-pox, &c., few will deny. That
plague and cholera are equally contagious many doubt. Sanitary works
and regulations of a very primitive and simple kind can certainly
check the contagibility of cholera, as witness the experience in
Newcastle-upon-Tyne and Tynemouth, in London, in many other English
towns and districts, and in the British hospitals and camps throughout
the Crimean campaign. The lesson taught by experience ought to be
this:--Let the Board of Health at Marseilles cleanse the town, cause
all the foul rooms to be ventilated and lime-washed, disinfect the
foul cesspools and sewage, and cut it off by “interception” from
the harbour and docks, and they may bid defiance to plague from any
quarter. It may be imported in silks, &c., but it will not spread.
Let there be a sanitary staff for the harbour, and another for the
town, armed with brooms, barrows, and lime-wash brushes, in place of
sidearms and muskets, and persons may land at once to go about their
business, and merchandize may be forwarded to its destination without
fear of consequences. During periods of epidemics there can be cholera
without dirt; improper food and mental and bodily exhaustion may bring
on isolated cases; but to have cholera rampant there must be numbers
of human beings fouling air, earth, and water, and habitually living
contrary to known sanitary laws and entirely neglecting sanitary

                                             CIVIL ENGINEER.

  _August 14, 1858._

NOTE 7.--_Mud, Water, and Air._

The presence of water and a suitable temperature are indispensable
conditions of the oxidizing process of decay, just as they are
necessary to putrefaction and fermentation. The sides of ponds and
ditches being covered by water during the winter months, in the
spring the air becoming warmer and drier, the water diminishes, the
decay of vegetable seeds, plants, and all woody fibres enter now
into putrefaction, communicating the process to each other, and by
the transmission of decomposition from one particle to another, a
great number of plants give out various gases to the atmosphere while
decaying upon mud, rise into the air, meeting other gases, and then,
floating about, they compose and decompose each other. Hence the bad
odour from the mud-banks of the Thames, near the outfalls of the sewage.


I have known fevers cured by a change of the sleeping room from the
south to the north aspect, and still more readily by removing from one
side of the street to the other. All should avoid dwelling near canals,
ponds, or ditches habitually covered with a white froth; this is
formed, in fact, of gases rising through humus swimming on the water,
and contains living beings as well as fermentable substances.

It is important to men who work and sleep in the same house to have
the day or working-rooms to the north, where the sun never enters, and
to sleep in a room to the east or south. A room to the west, looking
to the west, is not healthy, particularly in summer months, being the
hottest in the evening. Gnats, moths, and flies collect there, and are
at least harassing, if not hurtful, particularly to infants.

No person not a native of a marshy country should travel overland in
the evening; dew causes a strong action in vapours, mists, &c. Invalids
and soldiers after fatigue, should halt in the daytime, and march in
the evening, to avoid being chilled.


A sure remedy against the malaria of ditches, ponds, &c., is to fill
the water-courses with water; never suffer them to be so far dried up
that the spawn of living creatures may attach itself to the sides of
grass, bushes, &c., and afterwards to dry and spread about like the
seeds of flowers, in the environs. The mud which is left exposed to the
air gives out, on drying, various gases, which being mixed with the
fossils of the mud, contaminate the air, and are breathed by the people
in the neighbourhood.

A circular drain, having a double current, well understood by the
hydraulic engineers of Holland, is the kind of drain I prefer.



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