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Title: Epidemics Examined and Explained: or, Living Germs Proved by Analogy to be a Source of Disease
Author: Grove, John
Language: English
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Transcriber's note: A few typographical errors have been corrected: they
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       *       *       *       *       *


Page numbers enclosed by curly braces (example: {25}) have been
incorporated to facilitate the use of the Table of Contents.

       *       *       *       *       *


EPIDEMICS

EXAMINED AND EXPLAINED:

OR,

LIVING GERMS

PROVED BY ANALOGY TO BE

A SOURCE OF DISEASE.

BY

JOHN GROVE, M.R.C.S.L.

AUTHOR OF "SULPHUR AS A REMEDY IN EPIDEMIC CHOLERA."

LONDON:

JAMES RIDGWAY, PICCADILLY.

MDCCCL.

       *       *       *       *       *


    "The tendencies of the mind, the turn of thought of whole ages, have
    frequently depended on prevailing diseases; for nothing exercises a
    more potent influence over man, either in disposing him to calmness and
    submission, or in kindling in him the wildest passions, than the
    proximity of inevitable and universal danger."--_Hecker's Epidemics of
    the Middle Ages._

    "The grand field of investigation lies immediately before us; we are
    trampling every hour upon things which to the ignorant seem nothing but
    dirt, but to the curious are precious as gold."--_Sewell on the
    Cultivation of the Intellect._

       *       *       *       *       *


TO

BENJAMIN GUY BABINGTON, F.R.S., M.D.,

PHYSICIAN TO GUY'S HOSPITAL,

AND

PRESIDENT OF THE EPIDEMIOLOGICAL SOCIETY,

ETC. ETC.

THESE PAGES ARE, BY HIS KIND PERMISSION,

Respectfully Dedicated,

BY HIS OBLIGED AND FAITHFUL SERVANT,

THE AUTHOR.

       *       *       *       *       *


{v}

PREFACE.

The following pages have been written with a view to render some aid in
establishing a sound and firm basis for future research, on that absorbing
topic, the Causes and Nature of Epidemic Diseases.

The amount of information already published on Fevers, on the Exanthemata,
and on the Plague, is truly astonishing, and the more so when it is
considered, that at present no rational account or explanation is given of
the causes of these affections.

It appears to me but reasonable to suppose that as every thing on this
earth has been created on a wise and unerring principle, Epidemic and
Infectious Diseases are only indicative of some serious errors in our
social arrangements and habits. The dangers and misery brought upon us by
disease, may, as shewn by Dr. Spurzheim and Mr. Combe, be warnings against
the infringement of the natural laws.

Indeed, what is more rational than to suppose that the Seeds of Disease are
coeval with the fall of man. His first disobedience {vi} brought
death:--that his subsequent errors should hasten its approaches is not to
be marvelled at. The undetected murderer, though he may escape the
punishment human justice would inflict upon him for his delinquency,
suffers a penalty in the tortures of conscience, infinitely more horrifying
than the most ignominious death. The law of nature is triumphant.

No less certain, though after a different manner, are the consequences of
minor forms of disobedience. It is so ordained, that certain diseases shall
arise, under peculiar conditions, which may have been brought about by a
train of causes, easily imagined, and difficult to be explained, but all
having their origin in the vices and errors of man in his moral and social
relations.

If man neglects the cultivation of the ground; with rank vegetation, the
germs of fever will invisibly grow and multiply; if he harbours that which
is rotten and corrupt, he is himself consumed by those agents destined to
remove the rottenness and corruption; it is a part of the law of nature
that there should be active and energetic agents for this purpose. The
seeds of disease, like the seeds of plants, may be shewn to have {vii}
their indigenous localities; like them they may be spread and multiplied;
like them they may lie dormant, and after awhile spring as it were into
active existence; like them, when the soil and other conditions favour,
they are ever ready to make their appearance. And this is the law, the
germs of all disease exist, and have existed. Despise the dictates of
nature, be careless of yourself and those around you, neglect to use the
means which a noble intelligence has placed at your command, and above all,
transgress the laws of God, then will disease pursue and attend you, as the
conscience of the murderer pursues and attends him until he is finally cut
off.

His wants and necessities, his sufferings and privations, are the basis of
the intellectual progress of man. The wonders of Omnipotence are revealed
through the whirlwind, the storm, the pestilence, and the famine.

The constructive and perceptive faculties of man have been developed by the
necessity of protecting himself from injury by winds and rains; his
intellectual faculties have been cultivated, by the sufferings of disease
having led him to the study of {viii} organization and life, to discover
the cause,--and to chemistry, and other sciences for the cure of his
ailments.

Famine and distress have aroused his emotions, and softened down his
asperities, so that what appears at first to be the infliction of a Curse
without Pity, is in reality a Judgment with Mercy.

It occurred to me, that on the formation of the Epidemiological Society,
the first question for consideration should be, What is the nature of those
agents, which induce Epidemic Diseases? are they composed of animate or
inanimate matter? In other words, do the manifestations of these diseases
exhibit the operations of living or of chemical forces.

Having, in my study, dwelt on the subject with an earnest desire to find
the truth, I put the suggestion, with my ideas, before the public to reject
or receive them. If they be rejected, I can but think a full discussion of
the enquiry will lead to the most important results. If they be received
with favour, I doubt not others, with more ability, will take up the strain
and resolve the discords into harmony.

  J. G.

  _Wandsworth, September, 1850._

{ix}

CONTENTS.

                                                                   PAGE
  INTRODUCTION                                                        1

  CHAPTER I.

  IS IT PROBABLE THAT EPIDEMIC, ENDEMIC, AND INFECTIOUS
  DISEASES, DEPEND UPON VITAL GERMS
  FOR THEIR MANIFESTATIONS?                                          11

  CHAPTER II.

  THE NUMBER AND VALUE OF FACTS TO SUPPORT
  THE PROPOSITION.

  SECTION I.--On Reproduction                                        22

  SECTION II.--Historical Notice of Epidemic Diseases                34

  SECTION III.--The Dispersion of Plants and Diseases                64

  SECTION IV.--The Relation between Epidemic and Endemic
  Diseases                                                           96

  CHAPTER III.

  THE REASONABLENESS OF THE APPLICATION OF
  THE FACTS TO THE INFERENCE.

  SECTION I.--The Chemical Theory of Epidemics untenable            108

  SECTION II.--The Animalcular Theory of Epidemics untenable        128

  SECTION III.--Sketch of the Physiology and Pathology of
  Plants and Animals                                                138

  CHAPTER IV.

  RESULTS IN PROOF OF THE TENABLENESS OF THE
  PROPOSITION.

  SECTION I.--Observations on some of the Laws of Epidemic
  Diseases                                                          155

  SECTION II.--What is the nature of those Poisons which most
  resemble the Morbid Poisons in their effects on the body?         166

  SECTION III.--What results do we obtain from the effects of
  remedial agents, in proof of the hypothesis?                      176

  CONCLUSION                                                        189

       *       *       *       *       *


{1}

INTRODUCTION.

It is one thing for a man to convince himself, but a very different thing
to be able to convince others.

I am not now speaking of a conviction arising from the impression made by a
few startling facts, nor of one forced on the mind by early prejudices, or
by the dogmas of the schools, but of a conviction arising from careful
enquiry.

In the course of that enquiry, the collector of facts, sees their relations
to the idea in his mind, in a multiplicity of ways, from their remaining,
each, as one succeeds the other, an appreciable time on the sensorium, and
undergoing a certain process of comparison and relation, with all other
facts and ideas which have been previously stored up. As the materials for
an edifice which have been shaped and prepared in accordance with the
completion of the design, so do the facts and ideas which are accumulated
{2} in the mind, become shaped and prepared for the elimination of a truth.
The ultimate design of the architect can no more be conceived by the
examination of the framework of a window, or the capital of a column, than
the whole truth of a proposition by the examination of separate facts; the
whole must be conceived and all the relations of all the parts thoroughly
understood, before the architect can be comprehended or the harmony of his
design appreciated.

The process of thought in the minds of the architect, and in the framer of
a proposition, is never exactly the same as in those who contemplate and
examine their completed works. Much may be done, however, by both to aid
others in comprehending them. The more accurately they keep in view the
course their minds have taken, the more readily will their descriptions be
understood.

To simplify the elements of our knowledge is to give others a ready access
to our thoughts.

To arrange the course of our ideas in harmony with the elements of our
knowledge should be the end of all writing, as it is the only means of
multiplying knowledge. {3}

It is not the mere accumulation of facts which constitutes science, any
more than a collection of building materials constitutes a house, it is the
arrangement and adaptation of the means to the end by which the house
becomes built and science cultivated.

These reflections have been suggested by the circumstance that for the last
3000 years and upwards, Pestilences have at certain intervals done their
work of destruction, and opened the springs of misery to untold millions,
and yet I see not that we are much further advanced as to the knowledge of
the cause of these inflictions than the Jews in the time of Moses. In the
Levitical law, as I shall have occasion more particularly to shew
hereafter, were directions specially given in reference to the plague of
leprosy; what means should be adopted for the cure of the disease, and for
preventing its extension, and moreover pointing very significantly to
certain facts having connexion with the cause of the affection. Since that
time historians generally, and medical writers in particular, have
diligently recorded their observations and accumulated facts, on the
various desolating plagues which {4} have afflicted mankind. Some of these
men have grappled with the whole subject, and endeavoured to shew the
presumed relation of the supposed causes in all their intricacies, but it
is hardly necessary to say that all have signally failed in their attempts
to furnish us with any practical information.

Satisfied in my own mind that the whole subject is beyond the labour of one
man, and impressed with the belief that the basis of the enquiry is in
anything but a satisfactory state, I have applied myself entirely to the
study of the groundwork only, as the primary proceeding for a solid
superstructure.

The days are past, when imaginary spirits, ethers, and astronomical
phenomena, were believed to have any essential influence over our destinies
in a physical point of view; we have therefore to deal with _matter_ in
some form or other.

The question, therefore, which I have proposed for enquiry, is, whether the
matter which causes epidemic and endemic diseases, exhibits the properties
of inorganic or organized matter.

The properties and qualities of organized {5} bodies, as well as those of
inorganic matter, need but be stated, and in some instances we may picture
to ourselves the object, without having seen it, and not be very far from a
true conception. But for this purpose a clear and definite idea must be
previously formed, and have taken possession of the mind, of the great
general divisions of objects in the material world.

Having made these preliminary remarks, I have suggested a certain mode of
procedure in making enquiries of this kind, not perhaps in strict
accordance with logical systems, but on the principle of nature's
operations in our own minds, which appears to me, when reduced to a
systematic and simple form, to be sufficiently clear and strict for
synthetical application, and so concise as to be usefully and practicably
applied.

In endeavouring to establish a theory for the explanation of extraordinary
phenomena, there are certain rules which should guide us in the thorny and
treacherous path of speculation. But these rules readily flow from the
train of thought, and if we examine our own minds during their operations,
we {6} shall find that the following is the course of our instinctive
reflections. It is a course we adopt as the test of theories when formed,
and is a guide in all cases for their construction.

We first commence with an idea, which exists in our minds in the form of a
proposition: then the following rules naturally suggest themselves:--

1. The probability of the value of our proposition from inference.

2. The number and value of facts to support the proposition.

3. The reasonableness of the application of the facts to the inference.

4. What amount of information in the form of results can be produced in
proof of the tenableness of the proposition.[1]

In illustration of the value of these rules the history of Dr. Jenner's
discovery affords an appropriate example. To use the words of Dr. Gregory,
"he appears very early in {7} life to have had his attention fixed by a
popular notion among the peasantry of Gloucestershire, of the existence of
an affection in the cow, supposed to afford security against the Small Pox;
but he was not successful in convincing his professional brethren of the
importance of the _idea_."

The popular notion of the peasantry originated the idea in Jenner's mind,
and it became fixed there as a proposition.

1. He commenced his enquiry by observing that the hands of milkers on the
dairy farms were subject to an eruption, and he _inferred_ that the notion
of the peasantry bore the stamp of probability, which strengthened the idea
in his mind and gave force to the proposition.

2. His next step was to accumulate facts; he found on enquiry that the
persons engaged on these farms in milking, possessed an immunity from Small
Pox to an extent sufficient to strengthen the value of his proposition.

3. The reasonableness of the application of the facts to the inference is
clear from the coincidence that the eruption on the hands of the dairy
people bore a striking {8} resemblance to the Small Pox, and as this
disease does not usually occur twice in the same individual, the inference
was most reasonable that this eruption protected the people from Small Pox.

4. We have but to take the almost universal adoption of vaccination, and
its acknowledged prophylactic powers against the propagation of Small Pox
to shew the application of our fourth rule.[2]

Between the conception of the idea and the accomplishment of Jenner's
designs, vaccination seems to have undergone an incubation of nearly twenty
years. During that period, with an energy and perseverance only to be
obtained by confidence, did this great man brood over and elaborate his
idea; and well might the 14th day of May, {9} 1796, be styled the birth day
of vaccination, for on that day was a child first inoculated from the hands
of a milker.

In adopting the above method I have endeavoured to bear in mind M.
Quetelet's observations on the requirements necessary for medical
authorship; he says, "All reasonable men will, I think, agree on this
point, that we must inform ourselves by observation, collect well-recorded
facts, render them rigorously comparable, before seeking to discuss them
with a view of declaring their relations, and methodically proceeding to
the appreciation of causes."

       *       *       *       *       *


{10}

{11}

CHAPTER I.

IS IT PROBABLE THAT EPIDEMIC, ENDEMIC, AND INFECTIOUS DISEASES, DEPEND UPON
VITAL GERMS FOR THEIR MANIFESTATIONS?

It is, I believe, almost universally considered that Epidemic, Endemic, and
Infectious diseases, originate from some imaginary poisons of a specific
nature, each disease having its own peculiar poison. That this conception
should have taken possession of the minds of men, is most natural from the
symptoms which characterize these diseases, but when we come to enquire
into the nature of these agents, or supposed poisons, we are at once struck
with the idea that they exhibit one peculiarity which separates them in a
marked manner, from those poisons with which we are familiar; for the
poisons of Small Pox, Measles, Scarlet Fever, Hooping Cough, Fever, &c.
possess the power of multiplication, or spontaneous increase, a property
which attaches only to the organic kingdom, and is never known in the
inorganic kingdom. The source of most of the poisons is to be found among
mineral or vegetable products. A mineral in combination with an acid or
oxygen may become a poison, and {12} nitrogen in various combinations with
oxygen, hydrogen, and carbon, or with carbon alone, may become a poison;
these combinations are, however, in most instances the products of
vegetable life, others again are obtained from the animal kingdom, such as
the poison of the serpent, &c. but in all of these instances, there is not
one in which the power of self-multiplication is to be found.

We are, therefore, constrained to admit that this feature, which
distinguishes poisons, is one well worthy attentive consideration. The
varieties of poisons may be classified into those which act topically as
escharotic poisons, those which act chemically on the blood, and those
whose effects are manifested in inducing a speedy annihilation of organic
or vital action, as in the case of hydrocyanic acid, which is supposed
specifically to affect the nervous centres from which originate the vital
manifestations. It is rather remarkable that the vital poisons (as I will
call them for distinction), seem to have their appropriate locality in the
blood, they do not primarily affect one organ more than another, all the
effects we witness resulting from them are to be traced progressively from
the blood to other parts of the body. When a person is inoculated with
small pox, a very minute portion (indeed it is impossible to say how minute
it may be) is sufficient, when absorbed, to excite a certain train of
symptoms, all due to absorption of the materies of the disease, and the
process by which {13} that materies arrives at maturity, is that known in
the vegetable world as the fructification; this process of fructification
is a process of development and increase.

I here may repeat that among all the poisons known, constituted as they are
of various combinations of elementary matter, they are without exception
destitute of the power of development or increase. Now, it is pretty
accurately known what amount of these poisons is necessary to produce their
effects on the living body; we can say how many drops are sufficient of
hydrocyanic acid of Scheeles strength, to destroy a man instantaneously.
Again, how many grains of arsenious acid are sufficient to induce such an
inflammatory condition of the stomach and intestine as will end in death,
and how many grains of morphia, will bring about a fatal coma,--but who
shall say the amount of the vital poisons necessary to produce their
results? It far exceeds the limit of conjecture, to what extent the
dilution of miasmatic or contagious matter may be carried, and the poison
yet be capable of committing in a short time the most frightful ravages.

We may fairly then infer, that if a quantity of matter inappreciable in
amount be sufficient to exhibit the characters of growth and increase, that
it is endowed with the properties of vitality. That the poisons of scarlet
fever, of measles, and of small-pox have this power of growth and increase,
is as much a matter of universal belief as that "the sun {14} will rise and
set to-morrow, and that all living beings will die."

This power of individual increase, or reproduction, is the very summit of
vital manifestation; indeed Coleridge, in his Theory of Life, (in which he
says, "I define life as the _principle of individuation_, or the power
which unites a given _all_ into a whole that is presupposed by all its
parts,") places reproduction in the first rank, and expresses his
hypothesis thus: "the constituent forces of life in the human living body
are, first, the power of length or reproduction; 2nd, the power of surface,
or irritability; 3rd, the power of depth, or sensibility--life itself is
neither of these separately, but the copula of all three."

Extensive research is not required to shew that many thinking men believe
in the existence of living organic beings, as the elements of contagious
and epidemic diseases; the idea indeed seems to flow spontaneously in that
direction. Whenever thought, and enduring contemplation, have been
concentrated on the subject, the result appears to have been the same, a
firm conviction in each individual mind that a vital force must be in
operation; or as Schlegel would define it, "a living reproductive power,
capable of and designed to develope and propagate itself."--"Its Maker
originally fixed and assigned to it the end towards which all its efforts
were ultimately to be directed."

Referring further to beings having the property of reproduction and
propagation, he says, (using {15} the word nature here evidently as the
vital principle for want of a better term,) "Nature indeed is not free like
man, but still is not a piece of dead clockwork. _There is life in
it._"--"Thus we know that even plants sleep, and that they too as much as
animals, though after a different sort, have a true impregnation and
propagation."

When Schlegel wrote this, how little could he have imagined the intricacy
of this proceeding among the lower forms of vegetation. It has been shewn
by Suminski, and verified by many others, that the mode of impregnation,
and the period at which it occurs in the ferns, do not at all correspond to
the general notion on this subject. He has discovered in the early
development of the frond of ferns certain cells, which he denominates
antheridia, or sperm cells; these contain in their cavity a number of
subordinate cells, each containing a spermatazoon. At a certain period of
the progress of the frond, the parent cells become ruptured and liberate
the spermatoza, these move about in a mucilaginous fluid, which bedews the
inferior surface of the frond, and become the means of impregnating the
germ cells, or pistillidia, with which they readily come in contact. Thus
the process of impregnation in these plants occurs during the germination,
or what corresponds to the period of germination in the seeds of exogenous
and endogenous plants.

I have referred to the discovery of Suminski in {16} this place to recal to
the mind the great and incomprehensible wonders of creation, for who could
conceive it possible or feasible that even for the impregnation of an
inferior vegetable, animal life should form an indispensable and essential
appurtenant of the process. Truly may we say with Coleridge, of plants and
insects, "so reciprocally inter-dependent and necessary are they to each
other, that we can almost as little think of vegetation without insects, as
of insects without vegetation."

I will make but two more quotations on the supposed vital character of the
germs of disease. "That the air and atmosphere of our globe is in the
highest degree full of life, I may, I think, take here for granted, and
generally admitted. It is, however, of a mixed kind and quality, combining
the refreshing breath of spring with the parching simooms of the desert,
and where the healthy odours fluctuate in chaotic struggle with the most
deadly vapours. What else in general _is the wide-spread and spreading
pestilence_, but a living propagation of foulness, corruption, and death?
Are not many poisons, _especially animal poisons, in a true sense, living
forces_?"--Schlegel.[3]

It were useless to multiply quotations to shew {17} that the opinions here
entertained are matters of general belief among thinking men.[4] I will at
once then conclude with an observation of Dr. C. J. B. Williams: he puts
the question, "Does the matter of contagion consist of vegetable seeds? Are
infectious diseases the results of the operations and invasions of living
parasites, disturbing in sundry ways the structures and functions of the
body, each after its own kind, until the vital powers either fail or
succeed in expelling the invading tribes from the system?"

And this expression, the seeds, is an universal expression, it is a
"Household Word" in connexion with disease. That it has obtained this
position in the popular vocabulary is alone a proof of the applicability of
the term to the thing intended to be {18} signified. Popular notions, as we
have seen in the case of Jenner's discovery, are not to be unheeded. An
instance occurs to me, it was a popular belief, that in acne punctata, the
matter of a sebaceous follicle, was itself, when pressed out, a worm, the
dark portion which results from the accumulation of dust upon the matter at
the mouth of the follicle was supposed to be the head of the maggot, as it
was called; subsequent observation, however, has proved that though this
matter is not a worm, it contains an animal within its substance, the
Acarus folliculorum.

The popular notions found among savage tribes as to the efficacy of certain
remedies in the cure of disease have been the means of furnishing us with
some of our most valuable medicines, indeed it is almost impossible to say
whether originally man did not derive his remedies from the herbs and trees
by an instinctive faculty impelling him, as it does the animals when in a
state of liberty and with freedom of range, to seek certain plants as they
avoid others.

It is well known that animals when indisposed will find out some spot as if
almost led to it by a visionary guide where the "healing plant" is to be
discovered. I am told that sheep have this faculty, and that they will,
when affected with the rot, feed upon some plant when they can discover it,
which eradicates the disease.

Almost every one is familiar with the fact that cats and dogs will crop
herbage and eat it; I have {19} seen them frequently leave the house and
proceed to the grass in the most business-like manner, partake of some
quantity, and quietly return.

A close observer of diseased animals might obtain some useful information
by noticing the plants cropped by them while in that condition. The
observations should be made in a variety of districts in consequence of the
uncertain distribution of some even of the most commonly scattered plants;
in one year they may be abundant, but in another they may be almost
entirely absent from the same spot.[5]

Were it only on the fact of reproduction, I would be contented to take my
stand that the force of life is the indwelling power of pestilential
matter. Reproduction is a law of nature, and the law of nature is the law
of God. And where do we find He prevaricates with us? The more we study His
laws the more harmony and perfection we find; what is seeming confusion in
the ignorance of to-day, is order in the knowledge of to-morrow. If any one
ignorant of the law which regulates the diffusion of gases were {20} told
that a heavier gas would ascend contrary to its specific gravity through
the septum in a vessel containing a lighter gas above the heavier, he would
naturally doubt your assertion, and say, "that is contrary to the law of
gravity;" but explain to him the principle by which this comes about, and
the objects of the law; the order and beauty of the design become manifest.
But this is no equivocation, it is evidence there, that subordinate laws
exist and nothing more. It has never been found that men have gathered
"grapes of thorns and figs of thistles," nor has it ever been discovered
that inanimate matter multiplies itself. The seed of disease "is within
itself," multiplying and propagating itself; whether it formed a part of
creation at the beginning or not, is rather a question to be solved by
divines than physicians. When we know, however, the latency of seeds and
even of entire plants, and that they may be dried and remain so for years
yet being brought again into conditions adapted to their active existence,
they, as it were, revive from their sleep, and renew again their
reproductive properties: can we wonder if, in the great scheme of nature,
existences new to mankind should make their appearance? When the New
Zealander saw the surface of his ground producing to him unknown plants,
and the skins of his children generating peculiar eruptions, and each
propagating its kind, would he look, think you, to the wood or the stones,
the air or the water,--for the solution of the {21} mystery? No, he would
naturally say these people brought the _seeds_ with them. From the property
of reproduction possessed by these forms of matter, we infer the value of
the proposition.

       *       *       *       *       *


{22}

CHAPTER II.

THE NUMBER AND VALUE OF FACTS TO SUPPORT THE PROPOSITION.

--------

SECTION I.

ON REPRODUCTION.

It is inferred that the proposition, "_the matter which operates in the
production of Epidemic, Endemic, and Infectious Diseases, possesses the
property of vitality_," we proceed now to the enumeration of those facts
which further elucidate this subject.

The facts must necessarily be such as illustrate the identity of properties
in the imaginary germs, that are known to exist in demonstrable germs: we
take therefore the law of reproduction to be to life, what the law of
attraction is to gravitation.[6]

{23}

But further; do those matters which engender disease furnish to our minds
the properties inseparable from life in the abstract? Though the faculty of
reproduction is essentially an evidence that the thing which reproduces its
kind must be a living body, yet it is only a property or power of living
beings and is not itself life, it therefore is necessary to establish the
fact that the _materies morbi_ not only has the power of reproduction, but
also those properties which in the abstract will prove as far as
demonstration can go, that it has the essential properties common to all
living bodies.

I must again quote from Coleridge, he says: "By life I every where mean the
true idea of life, or that most general form under which life manifests
itself to us, which includes all its other forms. This I have stated to be
the _tendency to individuation_ and the degrees or intensities of life, to
consist in the progressive realization of this tendency. The {24} power
which is acknowledged to exist wherever the realization is found, must
subsist wherever the tendency is manifested. The power which comes forth
and stirs abroad in the bird, must be latent in the egg."

The tendency to individuation cannot be more strongly marked than in the
simple experiment of vaccination: we insert a small particle of the
so-called vaccine lymph under the skin, and by this means we multiply to an
enormous extent, the power which, in the first instance, we had in the form
of minute corpuscles in a dry and apparently inert state; nevertheless,
though in this condition there must have existed the tendency to
individuation or multiplication of individual existence, and the germs are
here to their active existence, as seen in the development of the vaccine
vesicle, what the egg is to the bird,[7] as described above; we may,
therefore, say that the power which exhibits itself in the production of a
vaccine vesicle, must have been latent in the dried matter. It is the
opinion of Muller that the entire vital principle of the egg {25} resides
in the germinal disk alone, and since _the external influences which act on
the germs_ of the most different organic beings are the same, we must
regard the simple germinal disk, consisting of granular amorphous matter,
as the potential whole of the future animal, endowed with the essential and
specific force or principle of the future being, and capable of increasing
the very small amount of this specific force and matter, which it already
possesses, by the assimilation of new matter.

After speaking of inanimate objects, Dr. Carpenter says; "and what compared
with the permanence of these is the duration of any structure subject to
the conditions of _vitality_? _To be born_, to grow, to arrive at maturity,
to decline, to die, to decay, is the sum of the history of every being that
lives; from man, in the pomp of royalty, or the pride of philosophy, to the
gay and thoughtless insect that glitters for a few hours in the sunbeam and
is seen no more; from the stately oak, the monarch of the forest through
successive centuries, to the humble fungus which shoots forth and withers
in a day."

To be born, signifies the faculty of reproduction existing or having
existed in an antecedent being to that one born, and also that itself
possesses equally a like power. To be born, is the first expression which
must be used in speaking of the faculties or properties of living beings as
independent existences, the annual formation of buds, trees, and shrubs, is
a multiplication of the species; the coral {26} and various budding polypes
increase by this process, indeed what is the seed of a plant, or the egg of
a bird, or the ovum of mammalia, but cast off buds; in all, the new being
was originally a portion of its parent, and if we examine the ovary of the
vegetable, the bird, or the mammal, can we find any expression more fitting
to designate the process than that of budding. To be born then, is the
evidence of an act of one living being, and the commencement of a series of
vital phenomena in another, but all these are subsequent to reproduction,
and constitute another chain of vital acts, all tending to a similar
result, the multiplication of the species.[8]

Now, whether we apply the philosophical language of Coleridge, or the
language of observation of Muller, in confirmation of the doctrine here
inculcated, we arrive at the same point.

Do we not witness in the newly formed vaccine vesicle, an increase of the
specific force and principle? We certainly have acquired by the process of
vaccination a manifold multiplication of power, and is there not also
assimilation of new matter in {27} which this power resides? And does not
every particle of this new matter contain within itself the same force and
principle, as existed in that which generated it?

"We revert again to potentiated length in the power of magnetism
(reproduction); to surface in the power of electricity, and to the
synthesis of both or potentiated depth in constructive, that is chemical
affinity."[9]

Some may be at a loss to conceive, at first, how irritability may be
considered a property of all vegetable matter; that it does exist in some
vegetables is certain, but that it does exist in all living beings is
equally certain;[10] the term, however, which would appear more appropriate
when that irritability does not exhibit itself in an appreciable form, is
_impressibility_. Irritability, as commonly understood, is seen in its
highest condition in muscular tissue; but "the irritable power and an
analogon of voluntary motion first dawn on us in the vegetable world in the
stamina and anthers at the period of {28} impregnation."--"The insect world
is the exponent of irritability, as the vegetable is of reproduction."

The property of irritability attains its acme in man, the most highly
organized of all beings; and its gradations pass downwards through the
whole scale of animate creation; not so reproduction, for this faculty
observes the very opposite direction, for in plants a single impregnation
is sufficient for the evolution of myriads of detached lives.

Reproduction is a fact, it is an essential property of life, and is a
reality to us from observation; but irritability is not so tangible and
demonstrable a property. We nevertheless may assume its universality, from
the circumstance that we lose sight of it by imperceptible degrees; the
irritability of the sensitive plant is as much irritability as that of the
highly organized muscle; but because the faculty evades our perception, "in
tapering by degrees, becoming beautifully less," we have no reason for
pronouncing its total extinction at any one point of the vegetable
kingdom,[11] any more than we should have {29} in saying that we see the
end of the earth, when describing the extent of our vision as we stand on
the sea shore. The extreme limit of our vision is the tangent of the circle
in reference to our visual organs; but how many tangential points there may
be beyond, it is impossible to say without knowing the dimensions of the
circle.

I think we are now in a condition to assume, as far as abstraction will
conduct us without proceeding to an extreme length, that the _materies
morbi_, or, as I will now call them for the sake of clearer distinction,
_semina morbi_, possess those properties which in the abstract are common
to all living beings.

Another argument strikes me as capable of adding further strength to the
proposition. We need but be told that a small piece of iron was placed in a
certain position with regard to another piece of iron, and that the smaller
piece moved through a given space and became attached to the larger, to
infer that magnetic force was in operation. Supposing this magnet then to
be folded in paper, and that it {30} be promiscuously placed near a
compass, the deflection of the needle would indicate that some object in
the vicinity was the cause of the deflection; we may farther try what
positions the needle takes by varying the position of the packet, and thus
point out which is the north and which the south pole of the screw of
paper. If we may consider attraction then to be to gravitation what
reproduction is to life, we do not err in saying in the one instance that
there is a living being, and in the other there is a magnet.

The nebular theory, from which some astronomers made the foundation of many
speculations, came with so much interest to our minds that the fascination
could not be resisted. It was most delightful to revel in the imagination
that we possessed a key to the mode of formation of the starry hosts, and
when speculation had taken its extreme limits in the "Vestiges of the
Natural History of Creation," and the nebulæ had served as the ground work
of a gigantic scheme, Lord Ross's monster telescope swept the heavens of
its cobwebs. We can imagine this great promoter of science saying to us,
Gentlemen, the clouds which have obscured you, are composed of myriads of
stars, and comprise systems as vast and as luminous as our own, had you but
power of vision to discern them. A new light thus appeared to philosophers,
and though no great practical results may flow from the discovery, it is
instructive from the fact that the imperfectly aided or unaided vision,
should not limit legitimate {31} inference. The nebulæ before Lord Ross's
discovery were to the astronomer what the materies of epidemic and
infectious disease are to medical men. In the absence however of a giant
microscope to reveal such great truths, we may yet dimly shadow them by the
light of our reason. It was predicted in 1849 that minute vegetable germs,
in all probability all of the same type, were the agents producing epidemic
and infectious disease. In 1850, Mr. Oke Spooner says,[12] "On examining
the matter of Small {32} Pox and Cow Pox in every stage, he finds its
essential character to consist of a number of minute cells not exceeding
the 10,000th part of an inch in diameter: being about one-fourth smaller
than the globules of the blood, containing within their circumference many
still more minute nuclei, and presenting beyond their circumference
bud-like cells of the same size and character as those contained within the
circle."

Should these observations made by Mr. Spooner turn out to be correct, they
will but fulfil my anticipations. Then again shall we see the same
application of imperfect vision to the limitation or temporary obstruction
of solid and determinate knowledge.

We may reasonably expect that these bodies, discovered by Mr. Spooner,
should be the elementary matters of disease. Their existence was predicted
from the probability that living matter must be the agent; moreover, that
this matter when discovered {33} would be cellular, most probably
resembling the yeast plant as described by Mr. Spooner.

It was predicted that a planet would be discovered in a certain position in
the heavens, because the perturbations of a comet indicated an attracting
body in the path of the eccentric wanderer; the prediction and the
fulfilment were almost simultaneous.

       *       *       *       *       *

{34}

SECTION II.

HISTORICAL NOTICE OF EPIDEMIC DISEASES.

The earliest notices we have of Pestilences are contained in Holy Writ. The
plagues which smote the Egyptians in the time of Moses are not unworthy
some comment here. Of those ten plagues, four out of the number were due to
the miraculous appearance of myriads of the lower animal tribes, in three
instances of insects,[13] viz. lice, flies, and locusts; in the fourth,
when Aaron stretched forth his hand with his rod over the streams, over the
rivers, and the ponds, frogs came up and covered the land of Egypt. In
these instances living beings are made the instruments in God's hand for
the punishment of the wicked. These plagues include the second, third,
fourth, and eighth. The first plague is mentioned as a conversion of the
waters into blood. Now if we may take this expression as being literal,
there is no reason to suppose that this blood differed in any respect from
ordinary sanguineous liquid; we therefore may assume, as the blood is every
where in Scripture spoken of as the _life_, that this fluid was endowed
with vital properties.

{35}

The fifth plague is described as a murrain among beasts; and the sixth, as
exhibiting itself as "a boil breaking forth with blains, upon man and upon
beast."[14] Now these affections bear a resemblance to the diseases known
to us at the present day through authentic records. The Black Death of the
14th century affords in its history but too awful a picture of the horrors
of such pestilences. In the tenth plague, the smiting of the first-born, we
are not told by what means it was brought about; but we have something even
here to lead us to conjecture. In the second visitation of the Black Death,
there were destroyed a great many children whom it had formerly spared, and
but few women. The seventh plague of hail is within our conception; as is
also that of darkness, the ninth plague.

It is not a little remarkable that of the ten plagues, seven of them
depended upon agents intelligible to our comprehension; we can conceive of
{36} the invasion of a country by myriads of loathsome insects and
reptiles, and can imagine the wrath of an offended Deity directing the
force of a supernatural storm of hail upon a disobedient people; and we can
conjecture, though faintly, the consternation of human nature on being
subjected to a total darkness of three days' duration, when we consider
_that_ darkness has been described, as "a darkness that might be felt."

From this abstract we discover that the three plagues whose causes we
cannot understand, or rather upon which no light has been thrown by
Scripture, bear analogies to those which we recognise, in the writings of
modern authors, as fearful pestilences.

It is now our province to reflect on the causes supposed to be in operation
in the three instances, which become naturally separated from the rest.

We are told that a murrain appeared among the cattle, without any
preliminary step. When the blains broke out upon man and beast, Moses had
been previously directed by the Almighty to take handfuls of the ashes of
the furnace, and sprinkle them towards the heaven in the sight of Pharaoh.
"_And it shall become small dust in all the land of Egypt_, and shall be a
boil breaking forth with blains upon man and upon beast, throughout all the
land of Egypt."

Another coincidence, in connexion with subsequent pestilences, arrests the
attention, on the subject of the mysterious appearance on these occasions
of {37} matter resembling dust being prevalent about the houses, and on the
clothes of the people. Clouds also, and showers of dust-like particles,
were not of infrequent occurrence. Indeed, in the summer of 1849, during
the progress of the Cholera, several phenomena of a similar nature were
observed and authenticated; I myself can bear testimony to one instance of
the kind. It was observed by many persons in my neighbourhood after the
passage of an ominous and lurid cloud, that as they walked their clothes
became covered with a singular dust-like matter of very peculiar
appearance. That this phenomenon was not destitute of significance may be
gathered from the fact, that on the night of that day several severe cases
of Cholera occurred, though our village had been comparatively free for ten
days.

Hecker, in writing on the Black Death says, the German accounts expressly
speak of a "thick stinking mist which advanced from the east,[15] and {38}
spread itself over Italy; there could be no deception in so palpable a
phenomenon." It is not unworthy of mention, that in the East successive
invasions of locusts "which had never perhaps darkened the sun in thicker
swarms," preceded the great outbreak of this disease, for they left famine
in their train.

From 1500 to 1503 in Germany and France, during the prevalence of the
sweating sickness, spots of different colours made their appearance,
"principally red, but also white, yellow, grey, and black, often in a very
short time, on the roofs of houses, on clothes, on the veils and
neckerchiefs of women, &c." Blood rain is also mentioned as having occurred
at this time, which consisted of the aggregation of minute particles of red
matter.

In the seven plagues, miraculous operations of the Deity consisted in the
unusual manifestation of phenomena, but which in their effects are
recognizable as of clear and definite import. The miracles here are,--in
the _mode_ of producing the swarms of frogs, locusts, &c. but they are
manifest and unmistakeable _causes_ of plague and famine; in the other
three, on the contrary, we witness only the effects, the causes are hidden
from us; we may, therefore, as in current events, legitimately investigate
the subject, and what better course can be adopted than that which
classifies the traditionary past with all subsequent history. Presuming
such a method of research to be admitted, I have assumed that as {39} the
_causes_ of the seven plagues have been distinctly given, the others,
though only mentioned in their effects, were due to causes of a nature in
some way to be compared with their concomitants, that is to say, if a
special intervention of the Deity brought about a miraculous appearance of
frogs, lice, &c. there is but little reason to doubt that some other agent
was miraculously multiplied and concentrated to induce the murrain,
engender the blain, and smite the first-born: as if to lead us into this
enquiry, on the visitation of the blain in man and beast, the Bible History
tells us that Moses threw ashes of the furnace, which became a dust
throughout all the land of Egypt; we cannot imagine that this simply as
ashes could have caused the blain, we may conclude that by some special
miracle, either the ashes were converted into a specific form of matter
capable of inducing the effects recorded, or that an independent septic
matter was generated for the purpose. If the latter, the act of throwing
the ashes of the furnace into the air may have been intended to signify
that the extremely minute division of the particles when thus cast into
space, typified the inscrutable and hidden nature of the matter endowed
with such marvellous properties.[16]

{40}

Further on in the book of Leviticus are passages which I cannot forbear
transcribing, for they point out to us most indubitably a line of enquiry
in reference to diseases of a contagious nature.

"The garment also that the plague of leprosy is in, whether it be a woollen
garment, or a linen garment, whether it be in the warp or woof, of linen or
of woollen, whether in a skin, or in any thing made of skin, and if the
plague be greenish or reddish in the garment ... it is a plague of leprosy,
and shall be shewed unto the Priest, and the Priest shall look upon the
plague and shut up it that hath the plague seven days; and he shall look on
the plague on the seventh day; if the plague be spread in the garment,
either in the warp, &c. ... the plague is a fretting leprosy, it is
unclean. He shall therefore burn that garment ... wherein the plague is,
for it is a fretting leprosy; it shall be burnt in the fire. And if the
Priest shall look, and behold, the plague be not spread in the garment ...
then the Priest shall command that they wash the thing wherein the plague
is, and he shall shut it up seven days more: and the Priest shall look on
the plague, after that it is washed: and behold if the plague have _not_
changed his colour, and the plague be not spread, it is unclean; thou {41}
shalt burn it in the fire; it is fret inward; whether it be bare within or
without. And if the Priest look and behold the plague be somewhat dark
after the washing of it, then he shall rend it out of the garment ... and
if it appear still in the garment either in the warp or the woof ... it is
a spreading plague: thou shalt burn that wherein the plague is with fire.
And the garment ... which thou shalt wash, if the plague be departed from
them, then it shall be washed the second time and shall be clean."--Chap.
xiii. 47-58.

Again in Deuteronomy. The curse for disobedience: "The Lord shall make the
pestilence cleave to thee until he have consumed thee from off the
land.--The Lord shall smite thee with a consumption, and with a fever, and
with an inflammation, and with an extreme burning, and with the drought,
and with blasting, and with _mildew_, and they shall pursue thee until thou
perish.--The Lord shall make the rain of thy land _powder_ and _dust_: from
heaven shall it come down upon thee until thou be destroyed."

It may be said, and I doubt not will be said, all this is unnecessarily
dragging the sacred volume into an enquiry totally foreign to its general
tenor; on the contrary, however, I maintain by that Book we are to learn
the ways of God to man, and further, that no study can impress mankind with
so awful, so terrific an idea of his responsible position, as that which
leads him into the investigation of the causes {42} by which the Almighty,
doubtless in His wisdom, has thought fit at various epochs of this world's
history, to place man face to face with pestilence, famine and sudden
death.

There is no man would less willingly than myself introduce profanely the
revelations of Scripture. The observations here made are not, therefore,
intended for light or heedless controversy; if they have a significance of
any import, let them be alluded to in the same spirit with which they have
been quoted; if they convey nothing for approval to the reader, let silence
rest upon them. To those who would fain disregard my request, let me recall
to their minds the veneration which from childhood I trust we have always
felt on hearing or seeing those two words--Holy Bible.

It is yet to be determined, whether the greenish or reddish appearance of
the garment spoken of, as being contaminated with the plague of the leprosy
had any specific relation to the disease itself. The priest orders that the
garment shall be shut up seven days, and on the seventh day, if the plague
be increased, by which, of course, is meant if the greenish or reddish
colour have increased, and from which we may gather that a power of
spontaneous increase was possessed by the matter, such a result indicated a
fretting leprosy, and the garment was to be burnt. Again, though there may
have been no increase, but a persistence of the coloured matter after
shutting up and washing the garment, it is to {43} be burnt, for it is fret
inward, signifying, that the germs of the affection are still there, and
may soon increase. Other rules follow in reference to the plague of
leprosy, and the mode of deciding whether an article be unclean or clean is
definitely laid down, but our purpose is served in mentioning the above, to
shew that in the time of Moses the spontaneous increase of certain minute
multiplying germs was supposed to have a close connexion with disease. It
is equally clear, that the priests were aware by the order given them, that
if the ordinary modes of purifying articles of clothing failed in their
effect, the safest and surest method of destroying infectious matter was to
resort to the practice of consuming by fire all materials capable of
propagating an infectious malady.

The facts above noticed, accurately correspond to what we now know as
applicable to the matter of infectious and contagious maladies. It is a
rule, I believe universally adopted throughout the Poor-houses of this
country, to put the clothes of all persons about to become residents in
these establishments, into ovens, where they are submitted to a temperature
incompatible with the existence of either animal or vegetable life. By this
means all living matters are destroyed, but the fabrics and inorganic
matters retain their properties intact. This simple proceeding, I am
credibly informed, is an effectual preventive of contamination by articles
of clothing, a desideratum of no small importance, when it is {44}
remembered that the diseases among the poor owe much of their inveteracy to
the accumulation of effete organic matters about their persons and clothes.

A few more observations are called for on the quotation from Deuteronomy,
in which allusion is made to living matter being an agent in the production
of disease. In the curse upon the children of Israel for disobedience, we
read that they are to be smitten with mildew. No further information,
however, is vouchsafed to us, nevertheless, we can conceive the wretched
condition of those on whom the curse might fall. Again, we find in a
continuation of this curse that the Almighty uses means such as He adopted
in the sixth plague of the Egyptians. The ashes of the furnace became a
small dust in all the land of Egypt, breaking forth with blains upon man
and beast. In the curse of the Israelites the words are: "The Lord shall
make the rain of thy land _powder and dust_: from Heaven shall it come down
upon thee until thou be destroyed."

It might be conjectured that the absence of rain would be sufficient to
account for the extinction of the people on whom the curse was pronounced,
by the famine and drought necessarily attendant upon the loss of moisture.
But this does not appear to be the meaning of the passage, for the powder
and dust are mentioned as the agents of destruction; besides, in the
continuation of the curse, the locust is to destroy the grain, the worm the
grapes, and {45} the olive is to shed his fruit; we may thus take for
granted that drought and famine are not to be caused by the showering of
powder and dust, it must consequently be supposed that the effects of the
dust in the instance of the Egyptians are to be compared and classified
with those of the dust which smote the Israelites.

As far then as Sacred History conducts us in the enquiry, concerning the
causes of pestilences, we gain encouragement in the belief that living
germs are the active agents, for in the case of the leprosy, we have
evidence of reproduction in connexion with infection, which, if our line of
argument be tenable, amounts to demonstration; then, in the other instances
of the plagues, by boils and blains, they distinctly bear comparison with
the accounts given by profane writers, of the visitations of pestilences on
the earth, subsequently to those mentioned in Scripture history.

This leads now to the consideration of recorded facts observed and noted
during the various Epidemics in the early and subsequent periods of Man's
History, as given by those on whom reliance may be fairly placed.

Setting aside the uncertain information contained in the writings of the
Chinese,[17] a people whose {46} progress in the science and practice of
Medicine has nothing to commend it (even as it is at the present day) to
the notice either of the physician or the historian, unless it be to the
latter as a mark of peculiarity both in a social and political point of
view,--passing also over the Egyptians, the Arabians, and the Greeks,--and
even Hippocrates himself, we are driven to the Romans for any authentic or
precise notice of Epidemic Affections. It has been attributed to
Hippocrates that he predicted the appearance of the Plague at Athens, {47}
and that when it was introduced into Greece he dispelled it, "by purifying
the air with fires into which were thrown sweet-scented herbs and flowers
along with other perfumes."[18] But little advantage can be derived from
enquiries concerning the first appearance of any disease, for the
probability of discovering the primary cause is certainly a {48} hopeless
case, if attempted by means of the writings of ancient authors, when it is
recollected that with all the science and learning of the ancient
Egyptians, the use of optical instruments was not comprised among the
paraphernalia of their arts. The knowledge that was limited to the powers
of natural vision, where the foundation of knowledge is based upon facts
obtained through the aid of that penetrator of nature's secrets, the
microscope, offers no advantages to the student of the present day.

To say that a disease commenced in the East and travelled westward, and at
length found a habitation and a name in every part of the globe, is no more
than to say that disease is coeval with the fall of man. The cause is as
much hidden in the region of its birth, as in that where it sojourns for a
time. The cause of the sweating sickness was as much a mystery in England
as in all the other nations of Europe, which were visited by its
devastating power. And these observations apply with as much force to one
disease as another; for even our indigenous ague, originating in some
places so limited that the shadow of a passing cloud may mark the boundary
of its dwelling place, as inscrutably evades our vigilance, with all the
appliances that art can bring to our assistance, in endeavouring to evoke
its extraordinary properties under the cognizance of our senses.

If we weigh the air which carries the poison, or analyze it by the most
delicate chemical tests, or {49} take the weight of the atmosphere which is
charged with it, or if we take the blood which carries the germs of the
disease to the tissues of the body, and submit them after the work of
destruction is accomplished, to the most rigid inspection, we can but
exclaim,

 "These are Thy marvellous works!"

and confess our total inability to fathom the unbounded.

If then no practical advantage can accrue from investigating the writings
of the ancients on these subjects, beyond comparing their historical
statements with those of more recent date, our purpose will be served by
occasionally embodying any remarkable observations of the former with those
of the latter.

In proceeding with this course it were better to confine our minds chiefly
to two diseases which appear from history to have been known from the
earliest periods, these are the Plague and the Small Pox, mentioning other
diseases only _en route_.

Passing then, to the sixth century of the Christian era for the first
distinct and connected account of the Plague, it appears from a host of
testimony, that the history of this disease, as given by Procopius, well
merits our attention. Drs. Friend and Hamilton, in their Histories of
Medicine, and Gibbon, in his History of Rome, are equally warm in their
praise of Procopius: the latter says, he "emulated the skill and diligence
of Thucydides in the {50} description of the Plague at Athens." The account
given by Procopius of this disease, does not differ materially from that
given by subsequent eye-witnesses of similar pestilences. Its point of
origin is clearly marked, and its mode of dispersion in all directions
distinctly traced from "the neighbourhood of Pelusium, between the
Serbonian bog and the eastern channel of the Nile." It commenced in the
year 542. It raged in Constantinople in the following year, and it was in
this city that our historian gathered the materials which are handed down
to us. When, however, we anxiously look for any explanation as to the cause
of the malady, we are told that it must have been a direct visitation from
Heaven, in consequence of the eccentric characters exhibited in its
wide-spreading influence, in not yielding to the scrutiny nor bending to
the laws known to prevail, and to regulate the course of other diseases:
neither country nor clime, age nor sex, the strong and healthy, nor the
weakly and previously diseased, could be said to be free from its
indiscriminate destruction.

But some phenomena preceding the outbreak of the pestilence are observed as
coincidences by all authors. Gibbon thus writes: "I shall conclude this
chapter with the comets, the earthquakes, and the plague which astonished
or afflicted the age of Justinian." From the accounts given by this author,
earthquakes for some years had been threatening and destroying many
portions of the globe, {51} that in the ruins of cities and in the chasms
of the earth, great was the sacrifice of human life. Constantinople, which
suffered so severely from the plague is said to have been shaken for forty
days. These great disturbances of the globe have been always looked upon as
indicating other and important influences of a secret or hidden nature;
these impressions on the minds of the people are traceable throughout the
histories of all epidemics, and have been sufficiently distinct among the
people of our own time, preceding and during the period of infliction.

From this short notice of the Plague of 543, I pass to the ninth century,
when Rhazes, the Arabian physician, endeavoured to enlighten the world on
the subject of Small Pox.[19] In quoting his opinions, I am not to be
understood as subscribing to them, but merely endeavouring to point out
some peculiar and interesting observations.

First, then, Rhazes attributes the disease to a condition of the blood,
which he thus describes, to shew how it happens that in infancy and
childhood the disease is most prevalent, and that old age is {52} least
liable to the affection.[20] "The blood of infants and children may be
compared to _must_, in which the coction leading to perfect ripeness has
not yet begun, nor the movement towards fermentation taken place; the blood
of young men may be compared to must which has already fermented and made a
hissing noise, and has thrown out abundant vapours and its superfluous
parts, like wine which is now still and quiet, and arrived at its full
strength, and as to the blood of old men, it may be compared to wine which
has now lost its strength, and is beginning to grow vapid and sour."

"Now the Small Pox arises when the blood putrifies and ferments, so that
the superfluous vapours are thrown out of it, and it is changed from the
blood of infants which is like must, into the blood of young men which is
like wine perfectly ripened: and the Small Pox itself may be compared to
the fermentation and the hissing noise which take place at that time."

But the cause of the disease is simply alluded to by this author, as
depending upon "occult dispositions in the air," and as he speaks here of
Measles with the Small Pox he goes on to say--"which necessarily cause
these diseases and predispose bodies to them." This notion of Rhazes that
there is some peculiar condition of the blood which favours a process
resembling fermentation is not without interest. The circumstance that
individuals are not {53} usually liable to a second attack of the disease,
no doubt directed the attention of this physician to compare the process of
fermentation with disease of such a nature, seeing that when the whole of
the saccharine matter was converted into spirit, the hissing noise, as he
calls it, or the disengagement of carbonic acid gas would cease, and the
capacity for fermentation be entirely gone. So that the occult conditions
of the air, their power of inducing a disease, and multiplying the matter
capable of engendering a similar affection, stood in the mind of Rhazes as
analogous if not identical phenomena.

We pass now without further comment to the epidemics of the Middle Ages;
and here the work of the philosophical Hecker leaves us little else to
desire in the way of information, as far as it is obtainable from published
records. From the manner in which he has grouped the facts which presented
themselves to his mind in the course of a most laborious research, he has
saved the student of this subject much toil in acquiring matter for
reflection; he has here but to read and digest.

I know not how to select from this invaluable work the most striking
passages, to strengthen and support my hypothesis, for not a page is
destitute of facts corroborative of the doctrine that vital germs are the
material agents of pestilential disorders. The opening paragraph to the
Black Death is a most cogent illustration of the assertion; it is, as it
were, the theme of the work. "That {54} Omnipotence, which has called the
world with all _its living creatures into one animated being_, especially
reveals himself in the desolation of great pestilences. The powers of
creation come into violent collision; the sultry dryness of the atmosphere;
the subterranean thunders; the mist of overflowing waters are the
harbingers of destruction. Nature is not satisfied with the ordinary
alternations of life and death, and the destroying angel waves over man and
beast his flaming sword."

I must here apologise for large transcripts from Hecker's work, for neither
could I command the amount of knowledge there displayed, nor use such
appropriate language as the learned translator has employed.

It is not doubted that the Black Death was an Oriental plague, only of more
than usual severity, and wider spread influence of the infectious nature of
this disease, and the active properties of the matter producing it. Hecker
says, "articles of this kind--bedding and clothes--removed from the access
of air, not only retain the matter of contagion for an indefinite period,
_but also increase its activity, and engender it like a living being_,
frightful ill consequences followed for many years after the first fury of
the pestilence was past."[21]

{55}

As extraordinary atmospheric and telluric phenomena preceded the Plague in
the time of Justinian, so do we find similar instances recorded as the
precursor of a similar visitation 700 years later. I am concerned more with
those circumstances which refer more especially to my subject, _viz._ the
development of organic matter, and the peculiar odours of the atmosphere,
the latter being evidence of some foreign and unusual production in our
respiratory media. "On the island of Cyprus, before the earthquake, a
pestiferous wind spread so poisonous an odour, that many being overpowered
by it, fell down suddenly and expired in dreadful agonies. A thick stinking
mist advanced from the east, and spread itself over Italy."

{56}

It is probable that the atmosphere contained foreign and sensibly
perceptible admixtures to a great extent, which, at least in the lower
regions, could not be decomposed or rendered ineffective by separation. In
1348 an unexampled earthquake shook Greece, Italy, and the neighbouring
countries. During this earthquake the wine in the casks became turbid, a
proof that changes causing a decomposition of the atmosphere had taken
place. "The insect tribe was wonderfully called into life, as if animated
beings were destined to complete the destruction which astral and telluric
powers had began."

"The corruption of the atmosphere came from the east, but the disease
itself came not upon the wings of the wind, but was only excited and
increased by the atmosphere where it had previously existed."

"The most powerful of all the springs of the disease was contagion; for in
the most distant countries, which had scarcely yet heard the echo of the
first concussion, the people fell a sacrifice to organic poison, the
untimely offspring of vital energies thrown into violent commotion."

"After the cessation of the Black Plague, a greater fecundity in women was
every where remarkable, a grand phenomena, which from its occurrence after
every destructive pestilence, proves to conviction the prevalence of a
higher power in the direction of general organic life." {57}

In the article Contagion, of the Essay, Sweating Sickness: "Most fevers
which are produced by general causes, propagate themselves for a time
spontaneously." "The exhalations of the affected become the germs of a
similar decomposition in those bodies which receive them, and produce in
these a like attack upon the internal organs, _and thus a merely morbid
phenomenon of life, shows that it possesses the fundamental property of all
life, that of propagating itself in an appropriate soil. On this point
there is no doubt, the phenomena which prove it have been observed from
time immemorial, in an endless variety of circumstances, but always with a
uniform manifestation of a fundamental law._"

Mead, in his Essay on the Plague, makes many observations of great interest
and worthy a physician of eminence; and where, in recent times, shall we
look for any more definite information concerning the causes of
pestilences? It is not a little singular that at the time this book was
published, it was read with such avidity that it went through seven
editions in one year.[22] From this circumstance we may gather that the
public generally took a lively and proper interest in a subject that was
not only of domestic, but national importance. Whether this interest was
stimulated by the fact that the work was written expressly by order of the
{58} government, it is now impossible to say, at any rate much credit is
due to the Lords of the Regency for having placed so important a duty upon
one so thoroughly and in every way so duly qualified for the task as Dr.
Mead. It had been well if some of the advice given at that time, as means
of protection against the Plague, had been applied and put in force during
the late visitation of epidemic Cholera, for, however the minds of some may
be convinced of the non-contagiousness of Cholera, there are many who hold
a different opinion, and all will acknowledge, that if not strictly a
contagious affection, it is clearly proved to be capable of being carried
from place to place, or to use Dr. Copland's words, it is "a portable
disease." But this is not the place to discuss the subject of contagion,
allusion will be made to it hereafter. To return, Mead's expressions are
singularly illustrative of the vital power possessed by the germs of
disease; he says, "There are instances of the distemper's being stopt by
the winter cold, and yet the seeds of it not destroyed, but only kept
unactive, _till the warmth of the following spring has given them new life
and force_. His confession as to the hidden cause of the disease, is worthy
transcribing: "We are acquainted too little with the laws, by which the
small parts of matter act upon each other, to be able precisely to
determine the qualities requisite to change animal juices into such
acrimonious humours, or to explain {59} how all the distinguishing symptoms
attending the disease are produced."[23]

On the spread of the Plague is the following:--"The plague is a _real
poison_, which being bred in the southern parts of the world, maintains
itself there by circulating from infected persons to goods, that when the
constitution of the air happens to favour infection, it rages with great
violence." Contagious matter is lodged in goods of a loose and soft
texture, which being packed up, and carried into other countries, let out,
when opened, the imprisoned seeds of contagion, and produce the disease
whenever the air is disposed to give them force, "otherwise they may be
dispersed without any considerable ill effects." Gibbon thus speaks of the
above quoted work: "I have read with pleasure Mead's short but elegant
Treatise concerning Pestilential Disorders;" many also might read it at the
present day with infinite advantage. Mead most satisfactorily combats the
opinions of the French physicians who maintained the non-contagiousness of
the Plague. Experience proves beyond doubt, that certain conditions of
atmosphere, of {60} which we are ignorant, favour the growth and increase
of pestilences as they do of all vegetation.

Dr. Bancroft was of opinion that specific contagions are each and severally
creatures of Divine Wisdom, as distinctly and designedly exerted for their
production, as it was to create the several species of animals and
vegetables around us.

The indigenous fever of Ireland, which has several times shewn itself in an
epidemic form, appears to have been as fatal, as the Plague in the South of
Europe. Its devastations have generally been associated or preceded by
famine and general distress. Dr. Harty, writing in 1820, says that thrice
within the last eighty years has the same fever appeared in its epidemic
character. In the year 1741 Ireland lost 80,000 of her inhabitants from
this cause. It is a maculated typhus, and considered to be a special
product of the Emerald Isle. It has been shewn that fever began to exceed
its ordinary rate in those places first where famine and want of employment
were most severely felt,[24] and that in such places and under such
circumstances, it was most prevalent and fatal. The physicians generally
believed it to have been spontaneously produced and not to have been
imported. In the last Famine Fever of Ireland, Liverpool and several other
places suffered severely from the {61} importation of their Channel
neighbours with the disease in some instances, and the infection in others
about their persons. Hitherto these have to all appearance been the limits
of the affection; we know not, however, how soon the time may come when the
invisible bonds which have thus chained the disease to certain localities
may be severed, and spreading itself like other pestilences in an
aggravated form, attack this country as a last and crowning act of
retributive justice. At present it has but cost us money and regrets, but
if the history of pestilences is to be heeded, there are many tokens which
seem to indicate that a few slight concurrent circumstances only are
wanting, to bring the full force of this disease upon us; then will there
be a sacrifice of life. Edinburgh and other towns of Scotland have had some
visitations already, ourselves but slightly, but let our labouring
population suffer to any large extent for want of work, and we shall
inevitably be the sufferers from that fever which in consequence of general
destitution is now always more or less prevalent in Ireland.

The Sweating Sickness prevailed in England alone at first, but at length
sought foreign victims. The Cholera is an exotic disease, as well as the
Plague, but they occasionally have visited our shores, and their seeds
remain among us. The Small Pox is now even not known in some parts of the
world, but when once it is established, who can predict the period of its
first appearance in an {62} epidemic form. The history of the disease
informs us that in all the countries where it has been introduced, sooner
or later an epidemic has seized the inhabitants.

A disease previously unknown in India appeared at Rangoon in the year 1824,
which obtained the name of Scarlatina Rheumatica. Four years afterwards it
attacked the Southern States of North America, and though the disease was
so impartial as scarcely to spare a single individual of any town to which
it extended its influence, it was not accompanied with that mortality which
has usually been the characteristic of wide spread epidemics.

There is one peculiar feature of all epidemics which may be here mentioned
as indicative of some definite, though at present unaccountable cause,
operating in the sudden suppression of the disease after a certain period
of duration. This distinctive character may almost be considered as a law
in reference to these affections; if we take three distinct diseases, the
Plague, the Irish Fever and the Cholera, we find the rule apply to all. Of
the latter disease we have so recently been witnesses, that I need not
quote authorities on this point concerning it. In Dr. Patrick Russell's
work on the Plague at Aleppo I find the following remarkable passage. After
alluding to the great increase of pestilential effluvia that there must be
towards the close of an epidemic, compared with the amount at the onset of
the disease, and expressing his {63} astonishment that so many escape
infection, he says: "The fact, however unaccountable, is unquestionably
certain; the distemper seems to be extinguished by some cause or causes
equally unknown, as those which concurred to render it more or less
epidemical in its advance and at its height." He then mentions that in
Europe the sudden cessation may be partly attributable to the measures
adopted for preventing its extension; but "at Aleppo, where the disease is
left to run its natural course, and few or no means of purification are
employed, it pursues nearly the same progress in different years; it
declines and revives in certain seasons, and at length, without the
interference of human aid, ceases entirely."

The expressions of Dr. Harty on this subject, in connexion with the Irish
Fever, would apply as well to all other epidemics: "It is a fact, that
though every diversity of management was resorted to for effecting the
suppression of the disease, yet, nevertheless, there was an almost
simultaneous and apparently spontaneous decline of the epidemic in the
various and most remote parts of Ireland. It is not an easy matter to offer
a satisfactory explanation of this circumstance, _some general cause must_
no doubt have influenced the subsidence of the disease, yet that cause
could not be atmospheric, inasmuch as the decline, though it might be said
to be simultaneous, was not sufficiently so to admit of that explanation."

       *       *       *       *       *

{64}

SECTION III.

THE DISPERSION OF PLANTS AND DISEASES.

The dispersion of Diseases and the dispersion of Plants, exhibit analogies
which might be little expected, on a superficial view of the enquiry.

We are led to believe, that the earth as a whole, was not covered with
vegetation in a day, the geological history of this planet is one of
development, and though at first sight this expression of opinion may
appear to savour of doubt in the Mosaic record, a more extended
acquaintance with the subject, favours rather and confirms Scripture
history.

As the peopling of the earth has been a gradual process with the animal
creation, so has it been also with the vegetable kingdom. We see at the
present day, that plants by various means of transit from place to place,
multiply themselves on new soils and in new climes, the same with animals.
By other means we observe, or can trace, the extinction from various
localities and countries, of members of both the animal and vegetable
kingdom.

We learn that originally this planet had a temperature much higher than at
present, and that the variation of temperature between the equator and the
poles, which we now witness, did not obtain in the earlier condition of the
globe. We are given to understand, and not without considerable proof, {65}
if not demonstration, that the earth was a vast bog, in which rank
vegetation grew, and in which the ichthyosauri and plesiosauri, must have
floundered about as unwieldy and loathsome bodies. We can readily conceive
a condition of atmosphere at this time to have been loaded with pestiferous
vapours of an organized nature; it is entirely in accordance with all we
know, that it should have been so. Allied forms of plants to those now in
existence, are found in the form of fossils, by which comparisons are made,
but how the transition into the present Flora took place, or at what
period, it is impossible to say. That these plants should have been
entirely destroyed during the revolutions of the earth by earthquakes, and
their consequences; the collection of waters into the vacuities formed, and
their draining off from other places by elevations of the land, is not to
be dwelt on without astonishment; then again the ultimate changes of
temperature on the surface of the earth, may have been another element in
the history of their extinction. But if we may be allowed to imagine that
there were organic germs floating in the vapours of the atmosphere, these
would hardly be subject to the same influences as those which depended
solely on their fixation to the soil for subsistence. The atmosphere, their
native element, being influenced by the commotions from below, would be
agitated; vortiginous currents would be established, hurricanes would sweep
over the stagnant pool and reeking morass, {66} and the higher regions of
the air might have thus given protection to these subtle germs, while
almost a total extinction of the elegant ferns, the stately palm, and the
towering cane was in course of procedure. Then when the strife of the earth
and elements had subsided, these would descend with the gentle breezes, and
again find in various spots a local habitation--

 "Where blue mists, through the unmoving atmosphere,
  Scatter the seeds of pestilence _and feed unnatural vegetation_."

In the new era, when the earth took its present physiognomy, who shall say
whether much of the pestiferous matter may not have been enclosed and
condensed in the bowels of the earth, and when it is remembered, that
earthquakes and convulsions of nature,[25] have invariably preceded the
outbreak of {67} any great pestilences, that stinking mists, coming from
some unknown regions, and unusual vegetations have made their appearance in
concert at these times, what I ask is more natural than to imagine, that
they have been let loose during the general convulsion? It may be asked,
what is to be said about that revolution of the earth, when the great
Deluge spread over the whole face of the globe? It can only be replied,
that this is a part of the scheme of cosmogony into which we are not called
upon to enter. There are yet strenuous supporters of the partial as well as
total submersion of this planet, but whether it be true that the vast
torrents which appear to have swept the surface uniformly in a southern
direction, were of a date coeval with the deluge, and constituted an
essential portion of the phenomena, of which one was, that "the fountains
of the great deep were broken up," or whether they were anterior to this
catastrophe, will not at all interfere with the conjecture of a very early
formation and propagation of the germs of pestilential diseases, for the
commotions of a deluge were less likely to interfere with the vapours of
the atmosphere, than extensive volcanic and electric disturbances.
Moreover, it is rather in favour of this theory, that the {68} regions
where the temperature and exhalations most nearly resemble those of the
former condition of the earth, are those in which pestilential disorders
most frequently arise, and where their virulence has always been most
strongly marked.

After the various commotions which left the globe, with its present
physiognomy of mountains, plains, valleys, rivers, lakes, and oceans; a new
Flora and Fauna appeared to adorn and animate the scene of man's existence.
Plants and animals were created apparently in adaptation to the numerous
climes, which the seasons in the various latitudes or the elevations of the
soil, were prepared to render fruitful and useful each in its own sphere.
Besides this, the plants of the same latitude, in some instances, differ
materially from each other; in this case it seems that the soil has much to
do with this peculiarity, for it is certain that the soil and the
contiguous atmosphere, have a close and intimate relation; the drought of
the desert depends upon the sand, as humid atmosphere is connected with the
morass. To illustrate the tendency which vegetation shews in appropriating
one locality more than another, I may quote the following: "Some of the
volcanic masses of the Æolian or Lipari Islands, that have existed beyond
the reach of history, are still without a blade of verdure; while others in
various parts, of little more than two hundred years date, bear spontaneous
vegetation, and the same is seen on two lavas of Etna near each other, for
the one {69} of 1536 is still black and arid, while that of 1636, is
covered with oaks, fruit trees, and vines."

In comparing the diffusion of plants, and the diffusion of diseases, the
different modes by which this generally has been effected may be considered
under heads, that the comparison may be more readily traced.

_First_, seeds are diffused by the atmosphere, either by the prevalence of
certain currents, which are produced by known laws, in which case, no
difficulty occurs in the explanations; or in a more imperceptible manner,
as by those more uncertain atmospheric currents of a partial nature, which,
though they seem to have laws governing them, are not yet understood.

_Second_, seeds are transported by water across oceans, &c. when they can
be floated on any material by which they are preserved, as by wrecks and
masses of wood, which have been washed down the rivers.

_Third_, they are conveyed by man to all parts of the globe.

_Fourth_, a period of latency is observed to apply to them, that is, they
require certain essential conditions before germination occurs; so that
even in some localities, a plant may not have been known to exist in a
particular neighbourhood, but by a train of circumstances, it may make its
appearance, and again be a centre of development.

1st. I shall not here wander into the speculation, {70} whether plants had
originally one birth-place, as a centre from which they spread by various
agencies, as supposed by Linnæus, nor into any enquiry beyond those facts,
which may fairly come within our own comprehension, and within our own
means of demonstration.

Many seeds are provided with means adapting them for floating in the
atmosphere, these are by pappi, or winglets and hairs, but it cannot be
doubted that the agency of atmospheric currents, is productive of
considerable effects in the dispersion of lighter seeds, such as those of
mosses, fungi, and lichens--lichens have been discovered in Brittany, which
are peculiar to Jamaica, and Monsieur De Candolle concludes, that their
seeds had been carried thence by the south-westerly winds, which prevail
during a great part of the year on this portion of the French coast.

But Humboldt's testimony on the subject of winds is most satisfactory, for
he says, "Small singing birds, and even butterflies, are found at sea, at
great distances from the coast (as I have several times had opportunities
of observing in the Pacific), being carried there by the force of the wind,
when storms come off the land." It is generally believed, from abundance of
proofs, that the trade winds, and other continuous currents, are means by
which plants are conveyed from one country to another.[26]

{71}

As to the partial currents, Humboldt further says, "The heated crust of the
earth occasions an ascending vertical current of air by which light bodies
are borne upwards. M. Boussingault, and Don Mariano De Rivero, in ascending
the summit of the Silla, one of the gneiss mountains of Caraccas, saw in
the middle of the day, about noon, whitish shining bodies rise from the
valley to the summit of the mountain, 5755 feet high, and then sink down
towards the neighbouring sea coast. These movements continued
uninterruptedly for the space of an hour. The whitish shining bodies proved
to be small agglomerations of straws, or blades of grass, which were
recognized by Professor Kunth, for a species of vilfa, a genus, which
together with agrostis, is very abundant in the provinces of Caraccas and
Cumana."

On the plague of locusts we read, that "the Lord brought an east wind upon
the land, all that day and all that night, and when it was morning the east
wind brought the locusts."

On the Black Death we read, "There were many locusts which had been blown
into the sea by a hurricane, and a dense and awful fog was seen in the
heavens, rising in the east, and descending upon Italy."

Of the Plague of 542, Gibbon says, "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 or {72} temperate regions of the
north. The disease alternately languished and revived, but it was not till
a calamitous period of fifty-two years, that mankind recovered their
health, or the air resumed its pure and salubrious quality."

In the history of the Sweating Sickness, of which there were five distinct
visitations, we find ample allusions to the atmosphere, and the mode in
which the disease was conveyed by this medium.

I quote again from Hecker: "It seemed that _the banks of the Severn_ were
the _focus of the malady_, and that from hence, a true impestation of the
atmosphere, was diffused in every direction. Whithersoever the winds wafted
the stinking mists, the inhabitants became infested with the sweating
sickness. _These poisonous clouds of mists were observed moving from place
to place_, with the disease in their train, affecting one town after
another, and morning and evening spreading their nauseating insufferable
stench. At greater distances, these clouds being dispersed by the wind,
became gradually attenuated yet their dispersion set no bounds to the
pestilence, and it was as if they had imparted to the lower strata of the
atmosphere, _a kind of ferment which went on engendering itself even
without the presence of the thick misty vapour_, and being received into
men's lungs, produced the frightful disease everywhere."[27]

{73}

Mr. K. B. Martin, harbour-master of Ramsgate, in a communication to Lord
Carlisle on the Cholera of last autumn, says, "At midnight of the 31st
August (1849), the Samson (steam-tug) proceeded to the Goodwin Sands, where
the crew were employed under the Trinity agent, assisting in work carried
on there by that corporation. While there, at 3 A.M. 1st September, _a hot
humid haze, with a bog-like smell_, passed over them; and the greater
number of the men there employed instantly felt a nausea. They were in two
parties. One man at work on the sand was obliged to be carried to the boat;
and before they reached the steam vessel at anchor, the cramps and spasm
had supervened upon the vomitings; but here they found two of the party on
board similarly affected. Here then is a very marked case without any known
predisposing local cause. Doubtless it was atmospheric, and in the hot
blast of pestilence which passed over them."

Many more instances might be quoted, to shew that the germs of disease, as
well as of plants, are borne on the wings of the wind from place to place
{74} in one country, and from one country to another, the distance being no
obstacle, however great that may be.[28] "Dust and sands," says Sharon
Turner, "heavier than many seeds, are borne by the winds and clouds for
several hundred miles across the atmosphere, falling on the earth and seas
as they pass along." "The clouds not only bring us occasionally meteoric
stones, hail, and _epidemics_, but also vegetable seeds."[29]

2nd. The transportation of seeds of plants by water requires very little
notice; every one is familiar with the mode in which coral islands, which
gradually rise out of the sea, become covered with vegetation. "If new
lands are formed, the organic forces are ever ready to cover the naked rock
with life.--Lichens form the first covering of the barren {75} rocks, where
afterwards lofty forest trees wave their airy summits. The successive
growth of mosses, grasses, herbaceous plants and shrubs or bushes, occupies
the intervening period of long but undetermined duration."

The following may be cited as an instance of the transportation of disease
by water. "Cyprus lost almost all its inhabitants, and ships without crews
were often seen in the Mediterranean, or afterwards in the North Sea,
driving about, _and spreading the plague wherever they went on shore_."[30]

It requires no argument to enforce the conviction that cottons, woollens,
furs, skins, &c. will retain the matter of infection for almost an
indefinite period; instances of the kind have been already given; it is
therefore easy to understand that portions of wrecks and ship's goods would
be a frequent though unsuspected source of infection. Dr. Halley mentions a
case, in which a bale of cotton was put on shore at Bermuda by stealth; it
lay above a month without prejudice, where it was hid, but when opened and
distributed among the inhabitants, it produced such a contagion that the
living scarce sufficed to bury the dead. Dr. Walker found seeds dropt
accidentally into the sea in the West Indies cast ashore on the Hebrides.
He says, "the sea and rivers waft more seed than sails." The waters of many
rivers induce diarrhoea and dysentery.[31] Well water also in many {76}
places has a similar effect, especially if any surface drainage happens to
find its way into the well.

3rd. The part performed by man himself in the communication of disease to
his fellow creatures, is perhaps the most fruitful source of the extensive
spread of epidemic and contagious diseases.

In the time of Moses, restrictions were laid on those who had the plague of
the leprosy to avoid contagion; the dictum for one so affected was, "he
shall dwell alone; without the camp shall his habitation be."[32] All the
ancient authors believed in the {77} infectious nature of pestilential
fevers, and some other diseases; but, according. to Mr. Adams, they held
that no specific virus was the cause, and merely a contamination of the
surrounding air by effluvia from the sick. Thucydides, Hippocrates,
Procopius, Galen, Plutarch, all recognized the property of communicability
from one individual to another of the plague; and Hecker, on the epidemics
of the middle ages, abounds with instances in support of contagion. As
regards small-pox and measles, Rhazes observes particularly the connection
that exists between the condition of the air and the severity or mildness
of these diseases, remarking that small-pox seldom happens to old men,
except in pestilential, putrid, and malignant constitutions of the air in
which this disease is usually prevalent.

The history of the introduction of Scarlet Fever, Hooping Cough, Lues, and
other diseases into the various countries of the globe, is sufficiently
convincing that men carry about with them the seeds of disease; that while
these attach themselves to the persons and clothing of those who introduce
them into new climes, and flourish independently of cultivation, yet the
exotics which they foster with so much care, often disappoint their most
sanguine expectations; and these "languishing in our {78} hothouses can
give but a very faint idea of the majestic vegetation of the tropical
zone." Art in this procedure fails to accomplish here, what nature but too
sadly, under some circumstances, effects most readily. The germs of some
diseases though of an exotic character, under congenial influences of
various kinds, appear to flourish with native vigour: is it not so, also,
with some forms of vegetation? The aloe, a native of Mexico, which lives,
but does not thrive well, or reproduce under ordinary circumstances in this
country, will occasionally send forth a most luxuriant blossom;[33] so rare
is this, that some say it occurs every 50 or 100 years, but no law seems to
be established on this point, any more than the statement that we may
expect pestilential diseases at certain intervals. But that there are
intervals of _uncertain_ duration when the aloe will blossom, when the
grapes will ripen, and a general productiveness of exotics will occur, is
as certain as that seasons will occur when contagion will be rife, and a
most unusual multiplication of disease prevail. This is not an imaginary or
speculative notion,--all observers of seasons and diseases within the last
twenty years, may fully verify the statement.

In 1846, a large vine, the black Hambro-grape, {79} ripened its fruit out
of doors, and was as fine as any green-house production; but during nine
years that the vine has been under my inspection, this was the only time I
have witnessed such a result.

We are apt to attribute an abundant or scarce fruit season to temperature
alone, but this is an error--for we have before remarked, that though
certain lands may be in the same degree of latitude, the plants which
thrive well on one land, will not do so on the other: in fine, that where
reason and analogy would lead one to expect a particular form of
vegetation, a totally different Flora is presented to the view. These facts
are indeed suggestive of new and important deductions. Is it yet explained
why the town of Birmingham should be free from Cholera? There is a large
manufacturing population, a great number of poor, the usual overcrowding of
individuals in small chambers, a considerable amount of destitution and
depravity; irregular habits of living, and unwholesome diet, and doubtless
many parts of the town, which on investigation would have yielded all the
elements usually considered necessary for the localization of the disease:
but no--here was some repelling cause, some opposing agent to the
generation and propagation of the pestilential seeds. There are no known
laws by which inorganic matter could be supposed to observe such a
selection, or such an antagonism. Electricity, magnetism, ozone, gases,
exhibit no such elective properties that here they will destroy, and {80}
there they will spare; that they can almost depopulate small villages, and
scarcely find a victim in Birmingham and Bath. But if we suppose a living,
and multiplying matter as the cause of disease, many local causes may
conspire to arrest the development of the germs, or perhaps, even utterly
destroy them.

4th. As to the time of latency, facts crowd upon us indefinitely, as
elements of comparison between vegetation generally, and disease in its
early stages and history. The seeds of plants are extraordinarily tenacious
of life. What a mysterious arrangement of the ultimate particles of matter
must there be, by which the vital force remains apparently inactive for
many years, and yet when the conditions arise favourable to its
manifestation, as it were by an extraordinary fiat, life appears.

Previous to the year 1715, no broom grew in the King's Park, at Stirling;
but in that year a camp was formed there, and the surface of the ground
consequently was broken in many places. Wherever it was broken, broom
sprang up. The plant was subsequently destroyed; but in 1745 a similar
growth appeared after the ground had been again broken for a like purpose.
Some time afterwards the park was ploughed up, and the broom became
generally spread over it. "In several places in the neighbourhood of
Edinburgh," says Professor Graham, "the breaking of the surface produces an
abundant crop of Fumaria parviflora, {81} although the same plant had never
before been observed in the neighbourhood. It is impossible to say the
lapse of time since these were buried, before they were again excited to
the performance of all their vital functions." Dr. Graham also gives
another proof of the vital force existing in seeds. "To the westward of
Stirling there is a large peat bog, a great part of which has been flooded
away by raising water from the River Teith, and discharging it into the
Forth,--the under soil of clay being then cultivated. The clergyman of the
parish standing by while the workmen were forming a ditch in this clay,
which had been covered with fourteen feet of peat earth, saw some seeds in
the clay which was thrown out of the ditch; he took some of them up and
sowed them: they germinated and produced a crop of Chrysanthemum septum.
What a period of years must have elapsed while the seeds were getting their
covering of clay, and while this clay became buried under fourteen feet of
peat earth!"[34]

{82}

What limit can there be to the dispersion of seeds when their vital
properties may remain so long unimpaired? The seeds of which we have been
speaking were, no doubt many of them, washed away with the waters of the
Teith, and carried by the stream into the Forth; and who shall then mark
their destination; for we have seen that by such means the most distant
lands are supplied with vegetation; for whence come the plants which cover
the Coral Islands, unless by the air and the water, and that both
contribute, has been incontestably proved. Dr. Lindley states that melon
seeds have been known to grow when forty-one years old; maize thirty years,
rye forty years, the sensitive plant sixty years, kidney-beans a hundred
years. But seeds in general have an indefinite period, apparently, at which
they can retain their power of germination; for many of the seeds which had
been kept in the herbarium of Tournefort for more than a century, were
found to have preserved their fertility.

It has now to be shewn that the germs of disease also retain their vital
powers in a state of dormancy during a lengthened period.

{83}

Mead has very judiciously observed, "to breed a distemper, and to give
force to it when bred, are two different things." He further remarks, that
the seeds of the Plague may confine themselves to a house or two during a
hard frosty winter, and be preserved, and again put forth their malignant
quality as soon as the warmth of the spring gives them force. It is
certainly very remarkable that the Plague of London, which commenced at the
latter end of the year 1664, should "lie asleep," as Mead says, from
Christmas to the middle of February, and then break out in the same parish.

It has been also known that an infected bed laid by for seven years had
done infinite mischief on being again brought into use. Indeed, it is quite
uncertain for how long a period woollen, fur, linen, cotton, and other
articles may retain infectious matter in a dormant state. It has been
supposed by some that in closely packed bed and body clothes a
multiplication of the germs may and does take place, nor do I see any
reason why this should not be the case, for these articles contain within
their structure the effluvia of the animal body, and they may possibly
there find sufficient nutriment for their development. Nees von Esenbeck
believed that some of the minute Cryptogamia were re-produced in the air,
we are not therefore exceeding philosophical conjecture when we imagine a
basis and substratum, though an unusual one, for the germs of vegetation.
Exclusion from air and light, {84} however, as would be the case in
packed-up clothes, would _a priori_ give a better colour to the conjecture,
as these are the usual conditions necessary for the growth of seeds.

Small Pox and Cow Pox matter, which are now proved to be the same virus,
the former modified by having been through a process of growth and
maturation in the cow, are both remarkable for exhibiting their active
properties after having lain dormant for a considerable time. And each,
though so closely allied, retaining its specific properties.

This peculiarity in the history of Small Pox virus suggests a comparison
with some phenomena of vegetation, _viz._ that of grafting or budding. The
lower Cryptogamia in their fructifications resemble rather multiplication
by buds than by seeds. M. Moyen's idea is that every spore or little
globule, independently of its neighbouring one, lives, absorbs,
assimilates, grows, and re-produces on its own account; this is certainly
the characteristic of the Torula and the Uredo, and doubtless is so of many
other of the Cryptogamia, the Protococcus nivalis is another instance.
Other modes of cultivation produce also great varieties of results of an
unexpected kind.

Would any one, says Dr. Walker, imagine that cabbage, cauliflower, savoy,
kale, brocoli, and turnip-rooted cabbage, were the same species? yet
nothing is more certain than that they are only varieties produced by the
cultivation of the Brassica oleracea, {85} a plant which grows wild on the
sea-shores of Europe.

These varieties in vegetables have now become permanent, and though it is
supposed that each is liable to return to its original condition, I am not
yet certain that such is the tendency. A deterioration is not unlikely to
ensue in the course of time, because the propagation by seeds must
necessarily very much approach the system of intermarriage, on which Mr.
Walker has so ably written and clearly shewn that as a result we may
invariably expect a deterioration of the species. Dr. Darwin has also
poetically described what his experience taught him.

 "So grafted trees with shadowy summits rise,
  Spread their fair blossoms and perfume the skies,
  _Till canker taints the vegetable blood_,
  Mines round the bark and feeds upon the wood;
  So years successive from perennial roots,
  The wire or bulb with lessened vigour shoots,
  Till curled leaves or barren flowers betray
  A waning lineage verging to decay;
  Or till amended by connubial powers,
  Rise seedling progenies from sexual flowers."

The minute nature of the germs of disease preclude all possibility of their
being submitted, as far as we know at present, to the inspection of the
physiologist, but we may infer many facts from results. In the same way,
though with humbler {86} ideas, as Cuvier could build up an animal from a
single bone, can we by a combination of facts infer the existence of living
beings and conjecture their forms. "The re-production or generation of
living organized bodies is the great criterion or characteristic which
distinguishes animation from mechanism." We find the virus of Small Pox,
according to Mr. Ceely's experiments, developing itself as a constitutional
disease upon the cow, and becoming modified into a form known as the Cow
Pox; this resembles the process of cultivation by which a species is
converted into a variety, this variety remains for a certain time
persistent; the time is not yet known, but it is known that by degrees, as
stated above, a deterioration occurs, and fertility becomes impaired, "a
waning lineage verging to decay," and this has been observed as a feature
in the result of vaccination. I believe Dr. Gregory was one of the first to
notice this fact, and deemed it necessary to obtain fresh lymph from the
cow; this has been done, and it is not improbable, if the analogy we have
drawn be correct, that the slowly spreading scepticism regarding
vaccination may be arrested in its progress. If we can explain the
deterioration of cow pox virus on this principle we have a hold at once
upon the public, and can assure them that the efficacy of the proceeding is
as certain as in the time of Jenner. The people, I contend, have a right to
demand of us the reason why vaccination is not so efficacious as formerly,
and I {87} affirm as unhesitatingly that we are bound to give the subject
our most earnest attention.[35]

Now concerning the re-production of Cow Pox matter, and assuming it to
resemble that of the lower Cryptogamia, we can easily understand how
degeneration in a course of years should ensue, for we find that though the
Small Pox is a constitutional disease, that produced by vaccine lymph is a
local affection, so that it bears the relation that grafting does to
vegetation, and it is not improbable that such a modification takes place
in the germs by passing through or becoming generated in the blood of the
cow, that they entirely lose their original and characteristic form of
reproduction: the seeds of the disease were originally capable of
vegetating, if I may be allowed to use the term, by diffusion through the
atmosphere; they now, however, have lost that property, and require to be
grafted to exhibit any manifestation of vitality.

How often will the seeds of a cultivated fruit grow? If you bud it upon
another plant, you obtain a being exactly like the parent, but this, as we
have seen, deteriorates in a course of years, we have also seen that the
virus deteriorates; but not to stretch this point to an unseemly length, I
cannot avoid expressing my conviction, that these are elements of
comparison, possessing an interest and a practical utility of no small
value.

{88}

I have before said, that the reproduction in the Cryptogamia, rather
resembles budding than seeding. If we observe the Torula, or take the
process of all formation, generally it will be found to accord more exactly
with the budding than the seeding process, and this peculiarity is not
confined to vegetation, it is also a marked feature in the reproduction of
infusoria, sponges, polypes, &c.

    "New buds surround the microscopic plant."

The reproduction of plants and animals appears to be of two kinds, solitary
and sexual; the former occurs in the formation of the buds of trees, and
the bulbs of tulips.

The microscopic productions of spontaneous vitality propagate by solitary
generation only.

We have but reached the threshold of this vast and interesting subject, the
experiments which suggest themselves to the mind while reflecting upon it,
would alone occupy a whole life of leisure, and I can but feel how forcibly
Mr. Sewell's words apply to us: "The grand field of investigation lies
immediately before us, we are trampling every hour upon things which to the
ignorant seem nothing but dirt, but to the curious are precious as gold."

It is difficult, perhaps, to bring many instances, in which the germs of
disease have lain dormant for a lengthened period, because many may take
exception to them, from the fact, that sporadic cases of {89} most epidemic
and infectious diseases, are rarely absent from any country in which those
diseases have become indigenous, and these cases may be said to be the foci
whence originates the epidemic constitution of the air; this, however,
would not invalidate the supposition, because one of two inferences must be
drawn, either that the germs of disease always exist in a dormant state,
requiring circumstances and conditions only for their development, or that
the germs are imported from some distant locality, where the disease has
occurred, and finding a nidus there, grow and multiply.[36] Whichever
notion we take, however, matters very little to the fact of the dormancy of
the germs, for in both, a certain period elapses between their transmission
and their propagation. It may fairly be presumed, that sometimes one method
may apply {90} and sometimes the other, perhaps both during general
epidemic conditions of the atmosphere.

The Oidium vitis attacked the vines partially last year, and I believe
generally spared other forms of vegetation; but this year in my vicinity,
cucumbers, melons, and vegetable marrows, are all suffering more or less
under the disease.[37] How shall we say, whether are the seeds of last year
the cause of the general diffusion at the present time, or were there a
sufficient number of old and dormant seeds, universally diffused, and only
waiting opportunities for multiplying themselves? We are here on the horns
of a dilemma; and spontaneous generation, from which one naturally shrinks,
can alone extricate us, if we do not admit diffusion and dormancy. I think
I may, without undue assumption, affirm that a period of latency of
indefinite duration, applies as cogently to the germs of disease as to
those of plants.

There is yet one other point in connection with this subject, and that is
the apparent extinction of some diseases, at any rate their non-appearance
in certain localities, which had been at one time congenial to them, and in
which they flourished. We have seen, in illustrating the dormancy of seeds,
that the broom must have been a common plant at {91} some considerable
period back, in the King's Park at Stirling, or on that site.

Then again, the appearance of Fumaria parviflora in the vicinity of
Edinburgh, in several places where the ground is broken, is sufficiently
convincing that this plant must once have been a common form of vegetation
there; and as it had never before been observed in the neighbourhood, there
must have been a combination of peculiar circumstances capable of rendering
germination impossible, otherwise a continued multiplication, as in other
forms of vegetation, would have followed of necessity.

But besides these instances, how many are passing under our own eyes of the
disappearance of plants under the influence of cultivation, and the
generation of the noxious fumes arising from different and innumerable
manufactories. In the vicinity of large cities and manufacturing towns, how
rarely do we see healthy vegetation; shrubs and animals drag on a sickly
and almost unprolific existence, and their term of natural life is much
shortened.

And if we compare diseases with this peculiar feature of vegetation, how
very close do we find the analogies. The Sweating Sickness which appeared
in the latter part of the fifteenth century, and at certain intervals
multiplied and extended itself at first only in this country, but
ultimately more or less over the continent of Europe, has {92} never since
the year 1551 shewn any symptom of productiveness, indeed for all we know
the disease may be extinct; on the other hand, it is impossible to say
whether or not circumstances may arise, under which it may commence again,
to put forth its energies and again desolate the land.[38]

Since 1665, the Bubo-plague has not found a congenial soil in this country,
or if the seeds be here, which is more than probable, the necessary
conditions to excite them to activity do not exist.

It cannot be imagined that with all the merchandize which comes into this
country from the Mediterranean, but that an abundance of the germs of the
disease are annually brought into our ports, and disseminated throughout
the land. The law by which we have seen that they possess a power of
vitality and reproduction, holds now as it did in former times;--the
properties of matter never alter, but the conditions under which they exist
may be so modified, as to influence their properties, and the usual course
of their operations. It is therefore to {93} an alteration or modification
of conditions that we are to look for the exemption, during the last two
centuries, from an invasion of the Plague. To say what those conditions may
be in their totality is difficult, perhaps impossible. We may generalize on
the subject, and imagine the reason discovered, but all those causes which
were said to have conspired to favour the spread and contamination with
Plague, were as distinctly specified and attributed, as the cause of our
late infliction with Epidemic Cholera. Why then did we have the Cholera and
not the Plague? To what particular element was it--in the mode of living,
of destitution, of filth and want of drainage--can it be ascribed that we
suffer under one disease, and not under the other?

We have made some few observations and comparisons on the mode of
dispersion of plants and diseases,--but there is yet one more point which
invites notice. Not only do seasons vary in their effects on vegetation in
a remarkable and unexplained manner, but there are many localities to which
some special form of vegetation attaches, and which appear to have a power
of exclusion of other forms; and as yet I have not been able to trace the
connexion, nor can I discover it in the writings of botanists and
travellers, who would be most likely to have sought an explanation of so
interesting and curious a fact. Dr. Prichard has on this subject some very
apposite illustrations. "Still further southward, the austral temperated
zone completely {94} changes the physiognomy of vegetation, and the Isle of
Norfolk has, in common with New Holland, the Auracania found also in the
harbour of Balade, and with New Zealand, the Phormium tenax. It is however
remarkable, that this vast island, composed of two lands, separated by a
channel, though so near New Holland, and lying under the same latitude,
differs from it so completely, that they display no resemblance in their
vegetation. Yet New Zealand, so rich in genera peculiar to its soil, and
little known, has some Indian plants: such as Pepper, the Olea, and a
reniform Fern, which is said to exist in the Isle of Maurice."

I must quote one more passage from Dr. Prichard's excellent work. "We have
one instance of an island at no great distance from a continent, having a
peculiar vegetation. Mr. R. Brown has remarked, that there is not even a
single indigenous species characterising the vegetation of St. Helena, that
has been found either on the banks of the Congo, or on any other part of
the Western coast of Africa. Does the diversity of marine and atmospheric
currents more completely separate this island from the continent, than its
situation would imply; or are the nature of soil and other local
circumstances, the cause of so marked a diversity? The last supposition
seems the most probable; because not only the species of plants, but
likewise the genera in St. Helena, are different from those of the African
coast." {95}

We are not without instances of diseases, observing this peculiarity which
attaches to plants; but their specific characters have hardly been
sufficiently considered in reference to climate and situation, together
with diet and local influences, to afford us accurate data for comparison.
It has, however, been remarked, in every country where Epidemics have
prevailed, that some districts or tracts of country, though supposed to
possess all the qualities favourable to the development of the diseases,
have nevertheless been entirely or nearly free from them. The following
passage on the course of the Cholera gives an example of this peculiarity.
"Whenever the malady deviated, so to speak, from its normal direction, and
passed towards the west, it seemed incapable of propagating itself; and
_died away spontaneously, even in places which appeared to be well fitted
for its reception_.--The rich fertile and densely peopled countries to the
right of the Dneiper, enjoyed an equal freedom from attack, which can only
be explained by the fact that they were situated _beyond the line of the
disease_." With this I close the subject of the diffusion of plants and
diseases, though it would require a volume of itself, to record all that
has been noticed. I have endeavoured to select such instances as shall mark
distinctly the features which point to comparison without overloading the
enquiry.

       *       *       *       *       *

{96}

SECTION IV.

THE RELATION BETWEEN EPIDEMIC AND ENDEMIC DISEASES.

Epidemic diseases, which multiply their germs in any climate, and under
apparently the most varying conditions of temperature and hygrometric and
electrical states of atmosphere, offer many points of contrast with Endemic
affections, and many of relationship. The latter are traceable to a certain
extent, to geological and geographical positions of the localities where
they are observed to prevail, in combination with atmospheric vicissitudes
and peculiarities, as well as to extent of cultivation of the soil: it has
been remarked that the sickly island (as it is called) of St. Lucia has
certain salubrious parts, but these are where sulphur abounds; this
geological peculiarity has been deemed sufficient to account for the
absence of endemic affections in these parts, and with much force of
reason; for in the neighbourhoods where sulphur or sulphurous acid, a
compound of sulphur, is an element prevalent in the soil or atmosphere,
vegetation and the ague disappear together.

Now ague, and other endemic fevers, doubtless originate from some allied,
if not identical cause; for the localities in which they appear have so
many {97} features in common, that we are constrained to acknowledge that
endemic fevers have some relations and analogies, though not yet
unravelled.

Geographical situation, together with certain vegetation, particularly of
grounds which grow rice, is one remarkable for the production of endemic
affections. But the soil which generates or gives force to the
contaminating matter, is not alone the part where human beings feel its
influence most severely. A low marshy ground, prolific of malaria, may be
comparatively free; while some neighbouring elevated land, to which
prevailing currents of air waft the volatile elements of disease, may be
desolated by their virulent and concentrated action. "Malaria may be
conveyed a considerable distance from its source, _and be condensed_ in the
exhaled vapour, when attracted by hills or acclivities in the vicinity, and
when there are no high trees or woods to confine it, or to intercept it in
its passage."

The inhabitants of the city of Abydos were at one time subject to disease,
arising from malaria, generated in some neighbouring marshes; by draining
these marshes, which suspended the growth of rank vegetation, the city
became healthy.

Rome is in like manner even now subject to fevers, having a similar origin.
Sir James Clark says, "Among the more prevalent diseases of Rome, malaria
fevers are the most remarkable, and claim our first notice." He considers
the fevers to be of exactly the same nature as those of Lincolnshire {98}
and Essex in this country, of Holland, and certain districts over the
greater part of the globe. To the climate, the season, or the concentration
of the cause of these fevers, he attributes their varieties. It is the same
disease, he says, whether from the swamps of Walcheren, or the pestilential
shores of Africa.

From July to October the inhabitants of Rome are most subject to these
affections.

Sir James Clark further says: "It may be stated as a general rule, that
houses in confined shaded situations, with damp courts or gardens, or
standing water close to them, are unhealthy in every climate and season;
but especially in a country subject to intermittent fevers, and during
summer and autumn. The exemption of the central parts of a large town from
these fevers, is explained by the dryness of the atmosphere, and by the
comparative equality of temperature which prevails there."

In this respect there is a marked difference between an epidemic and an
endemic affection; for when an epidemic disease attacks a city or town we
do not discover that the central parts are more exempt than others; indeed,
it is rather the contrary; for the most crowded parts of towns and cities
are those, if not exactly in the centre, which would be comprised in a
space nearer to the centre than the circumference; and it has been in those
parts generally where the epidemic influences seem to have exercised the
most potent sway. One would more naturally suppose, that a city surrounded
by {99} paludal miasm, and not itself being capable of generating the
poison, should be more affected at the circumference, from the simple fact
that the paludal germs, which rise in the air, are suspended in the fogs
and dews of the atmosphere. These, unless widely dispersed by the winds,
would remain within a comparatively confined space; and those situations
nearest to them would be most subject to their influence. Besides, it has
been shewn, that a small wood or hill, or even a wall, has been sufficient
to cut off or obstruct the paludal miasm.

Without enumerating all the known endemic diseases, two or three may be
alluded to for our present purpose; viz. that of shewing that endemic and
epidemic diseases have a similar origin.[39]

It is well known that under certain favouring conditions an endemic may
become a malignant and pestilential disease; that Yellow Fever, which is
always endemic in the west, Cholera in the east, and the Plague in the
south of Europe and north of Africa, every few years takes on an epidemic
form, and desolates considerable tracts of country.[39]

The Pestilence which raged in the summer and autumn of 1804 in Spain,
commenced at Malaga, and remained for a considerable time confined to its
{100} boundaries, in consequence of the measures of precaution that were
used, in preventing all communication between the inhabitants of the
infected city and those living in the surrounding country. It was only in
consequence of persons escaping through the cordon, and passing into the
interior of the country, that the disease spread, and extended its ravages
to distant places.

It appears to be quite clear, that this disease may properly be considered
in the first instance of endemic origin; but the tendencies, atmospheric
and otherwise, were such as to favour its multiplication in other districts
than that in which it first came into active existence. From this we may
infer, that the seeds of the disease were dormant, and only became roused
into vital activity by fortuitous circumstances. Dr. Rush states, that the
endemic disorders of Pennsylvania were converted, by clearing the soil, to
bilious and malignant remittents, and to destructive epidemics. Dr. Copland
says, it has been observed, especially in warm climates, and in hot seasons
in temperate countries, that when the air has been long undisturbed by high
winds and thunder-storms, and at the same time hot and moist, endemic
diseases have assumed a very severe and even epidemic character.

Dr. Robertson also confirms this view. "Endemic diseases, in cases of
neglect and preposterous management, are found to become more malignant
even in the most temperate climates; and to {101} generate a matter in
their course, capable of producing a particular disease in any
circumstances. _Indeed the origin of every_ contagious fever unattended
with eruptions, with the exception of Plague, must commence in this way."
Why Dr. Robertson should except eruptive Fevers and Plague I cannot
understand, for they must have had a commencement; and their many points of
similarity indicate, if not an identical, an analogous source to other
endemic fevers.

It will doubtless be generally acknowledged that endemic and epidemic
diseases depend upon some unknown agents, having their source in malarious
districts, and being capable of assuming either a contagious or
non-contagious character, according to circumstances.

If, therefore, we find that under any conditions an endemic affection
becomes capable of being propagated by contagion, the same law will hold
with regard to it as to the Plague; that the power of reproduction in this
matter is evidence of life, according to the doctrine laid down in the
earlier part of this work. But whether or not infection be admitted, a
matter generated in a malarious district, if confined in its effects to
that district alone, would not necessarily imply an inorganic nature of the
poison; for it is difficult to understand how inorganic poison, prevailing
generally over a certain tract of country, could select particular
individuals for its victims. If chloroform, chlorine, carbonic acid,
sulphuretted hydrogen, or even spores of poisonous fungi, (as {102}
supposed by Mitchell, which, as he regards their effects, would act in a
similar manner to inorganic compounds) were the agents, all persons would
suffer more or less, and the majority be similarly affected. We do not find
that uniformity of symptoms, which attend upon the exhibition of poisons in
the ordinary acceptation of the term, poisoning. This subject shall be more
particularly considered, when treating of the influence of organic germs on
animals and plants.

The history of the Eclair steamer is particularly interesting, as shewing
the extraordinary tenacity with which the germs of disease attach
themselves to vessels, which we may call floating houses.

The crew of the Eclair contracted Yellow Fever on the coast of Africa, and
a number of them died. The remainder, sick and well, landed at Bona Vista,
one of the Cape de Verde Islands, and the vessel underwent a process of
washing, whitewashing, and fumigating. Nevertheless, on the return of the
ship's company, the disease broke out again with equal intensity, and the
vessel was ordered home. Sixty-five out of 146 officers and men, who
composed the crew, died of the disease before reaching Portsmouth, and
twenty-three were sick at the time of arrival.

Eight days after the Eclair left Bona Vista, a Portuguese soldier who had
mixed with her crew died in the fort which had been occupied by them. Other
soldiers then fell sick, and the fort was abandoned. The fever still
spread.

From the 20th September, when the first soldier {103} was attacked, to the
first week in December, the fever continued to rage, and at that period it
had found its way into almost all the country villages. The fever was
believed to be the genuine black vomit fever; it proved contagious almost
without exception to the nurses of the sick.

This is an abstract of Mr. Rendell's letter to Lord Aberdeen, Mr. Rendell
being British Consul at Bona Vista.

Now at the time the fever broke out in the island the weather was
extraordinarily hot, and much rain had fallen, and the town itself was
badly drained and in a filthy state; can it be imagined then that the seeds
of a disease liable to assume a pestilential character should lie dormant
or be annihilated under circumstances the most favourable for their
development, especially when we know that endemic diseases may assume a
malignant character?

This is just one of many cases which confirm our opinion in this respect,
that plants and diseases are not long in making their appearance where the
soil and atmosphere are congenial.

The tenacity with which the disease attached itself to the Eclair is
sufficiently explained in the absence of due ventilation; in fact, that in
the first instance there was no ventilation at all in the hold of the ship.
This also the more readily affords a clue to the disaster through all its
stages, first in the contraction of the disease as an endemical affection
in the vessel; secondly, in the multiplication of the {104} germs in the
damp ill-ventilated hold, in a warm climate; and thirdly, the persistence
and entire localization of the disease to the vessel when it arrived in the
climate of the British shores; while, fourth and lastly, in the unusually
hot and damp island of Bona Vista, the seeds of the disease were sown, and,
as we might expect, multiplied indefinitely.

The consecutive attacks of the crew of the Eclair shew that here a noxious
gas or a vaporized inorganic poison could not have been the cause of the
disease, for as I have before said, in this case the attacks should have
been simultaneous; we find, on the contrary, that as the depressing effects
of the melancholy condition of the crew was almost hourly undermining the
health of the stoutest of them they as surely became the victims. The
Kroomen, or natives on board the ship had not suffered, shewing that they
were inured to the miasm, or were destitute of that condition of blood
which would be favourable to a propagation of the materies of the disease.

The Eclair we learn had left Bona Vista eight days when the first victim
breathed his last; this would give perhaps three or four days for the
incubation of the disease in the patient, or supposing he had not
contracted the germs of the disease before the crew of the Eclair left the
fort, some local favouring conditions were the means of keeping the germs
in a fertilizing state, for it is clear from this spot the infection spread
as from a centre or focus. {105} Such instances as these might be
multiplied to extend the length of the enquiry, but, I think, to little
advantage. The chief facts to be gathered are that an endemic affection
became epidemic and pestilential, contrary to its usual mode, for the
Portuguese official physician, on being consulted by the Governor of the
Island as to the safety of landing the contaminated crew, said, "No danger
at all; I have often brought sick men on shore coming in vessels from the
African coast, and I never knew any ill effects to arise." Putting the most
reasonable construction on this emphatic and straightforward language, we
may presume that ordinary, remittent, and yellow fever had been commonly
imported into the island, for it is not to be supposed but that both forms
of disease must have existed among those sick men who had "_often been
landed_," under the sanction of the Portuguese physician.

To take another instance; intermittent fever or ague, is a disease known
among almost all nations of the world, but it usually occurs in the endemic
form only. It is universally supposed to depend entirely upon marsh
effluvia, and we are accustomed to consider it as attaching only to low
lying countries;[40] but this is not always the case, for disease in {106}
this respect, like vegetation, may be found in various latitudes, to
accommodate itself at varying altitudes, to the temperature and climatic
relations, so as to appear indigenous. But though our prejudices are in
favour of a simple miasmatic source of ague, as its sole cause, there are
some who believe in its infectious nature. M. Sigaud, in his work on the
Climate and Diseases of Brazil, speaks of Epidemics of _grave intermittent
Fever_, and Dr. Copland says, that the epidemic prevalence of ague is a
better established fact than its infection, and has been admitted by most
writers.[41] We have, therefore, but to go one step further to arrive at
infection, after having found that an endemic disease under peculiar
circumstances, though but rarely, becomes {107} epidemic. The number of
persons attacked by ague in a malarious district, in proportion to the
population, is not so great as might be expected, considering that they are
always subject by night and day, more or less, to respire the air
containing the germs of intermittent fever; we might, therefore, deny the
paludal source of the affection, as reasonably as deny infection, if we
found that occasionally, persons, though subject to all the usual
influences, yet escaped all injurious consequences.

There are grades and varieties of infectious diseases, from the most
inveterate to the most mild and doubtful; but that all, without exception,
which can in any way be traced to a specific generating and organic cause,
may assume an exalted infectious character, and that the most inveterate,
on the contrary, may more resemble the mild and doubtfully infectious
forms, is a conviction that must be forced on all who pursue this enquiry
with unbiassed interest.

       *       *       *       *       *


{108}

CHAPTER III.

THE REASONABLENESS OF THE APPLICATION OF THE FACTS TO THE INFERENCE.

--------

SECTION I.

THE CHEMICAL THEORY OF EPIDEMICS UNTENABLE.

It has been inferred that the germs of disease possess the property of
vitality, and a number of facts have been adduced to support the
proposition that vitality is the indwelling force by which the matter
generating epidemic and endemic disease exercises its influence over man
and animals. The reasonableness of the application of these facts to the
end in view has now to be considered. Chemistry cannot account for
epidemics.

Our first subject of reflection points to the chemical discoveries of the
last few years, and particularly to those of the great German chemist
Liebig. We find in the first paragraph of his Organic Chemistry applied to
Physiology and Pathology, the following words: "In the animal ovum, as well
as in the seed of the plant, we recognize a certain remarkable force, _the
source of growth_ or increase in the mass, _and of reproduction_ or of
supply of the matter consumed; a force in a state of rest. By the action of
external influences, by impregnation, by the presence of air and moisture,
the condition {109} of static equilibrium is disturbed. This force is
called the _vital force_, _vis vitæ_, or vitality."

The doctrine of Liebig, that the vital force manifests itself in two
conditions, or rather, that it is known to be in two different states, that
of static equilibrium as in the seed, and in a dynamic state, as in that of
growth and reproduction, is perfectly applicable to the germs of disease;
the static equilibrium is referrible to the matter of vaccine lymph when
dried and preserved for use, and the dynamic forces of the matter are known
to be in operation during its reproduction and growth in the system of the
vaccinated child.

Then as to reproduction of matter by any chemical process, our author can
furnish us with no examples, for even in his explanation of the causes of
disease he is quite silent on this point, merely acknowledging that
diseased products must be either rendered "harmless, destroyed, or expelled
from the body." He further says, that "in all diseases where the formation
of contagious matter and of exanthemata is accompanied by fever, two
diseased conditions simultaneously exist, and two processes are
simultaneously completed," and that it is by means of the blood as a
carrier of oxygen that neutralization or equilibrium is established. Liebig
thus admits that an agent exists in the blood, capable of deteriorating it
at the expense of the oxygen, which he maintains is contained in the red
globules; he further acknowledges that two processes of diseased {110}
action are going on at the same time, and though he does not explain them,
I imagine him to mean that new contagious matter is generated and
eliminated from the blood, and that at the same time, there is that
condition of body which he would call simply a diseased state, and
characterizes it thus: "Disease occurs when the sum of vital force which
tends to neutralize all causes of disturbance, (in other words, when the
resistance offered by the vital force) is weaker than the acting cause of
the disturbance."

If I rightly apprehend his notions, they perfectly harmonize with my ideas,
to a certain extent, on the subject. They accord, at any rate, most
completely with the theory attempted to be established, and fully confirm
the reasonableness of the application of the facts recorded to the
inference drawn from other sources. The difference only rests on the
question whether vitalized or non-vitalized matter is the _fons et origo
mali_.

How is the production of new matter, resembling that originally causing the
disease, to be explained by any known hypothesis, except on the assumption
of living organized matter? Though Liebig and Mulder both deny the fact,
that the Torula cerevisiæ is the sole agent in the process of fermentation:
they both equally fail in shewing upon what it does depend, and their
difficulty rests entirely on their incapacity to explain the uniform
reproductive properties of the matter engaged in this, as well as in all
other allied operations. Liebig's statement {111} however on this matter
requires notice--he says, "that _putrifying_ blood, white of egg, flesh and
cheese, produce the same effects in a solution of sugar, as yeast or
ferment. The explanation is simply this; that ferment or yeast is nothing
but vegetable fibrine, albumen or caseine, in a state of decomposition."

This state of decomposition, however, involves a much more complex
proceeding, than simply a reduction of matter into its elementary forms of
gases, earths, and minerals; for we nowhere find decomposition of this kind
going on without the development of some organized bodies, either animal or
vegetable: and since we have seen that the spores of the cryptogami are
always in existence in the atmosphere, and making their appearance under
favouring conditions, and especially when we find that fermentation is
invariably accompanied, and I may safely say, preceded by the deposition in
the fluid of the sporules of the Torula, we can hardly believe that they
are any other than the sole agents of the process. I have now a
considerable quantity of the Torula obtained from the urine of a diabetic
patient, in which they appeared, as it were, spontaneously. After the urine
had been allowed access to the air for a certain time, and the whole of the
saccharine matter was converted into new compounds, reproduction of the
Torula ceased;--and those which remained when the process was completed,
still continue as organic cells, deposited {112} in the bottle in an inert
state, but ready, on the addition of fresh sugar, as has been proved, to
resume an active existence. These germs, it is now well known, may be dried
into powder, so as to be blown away like dust without any, or but little,
detriment to their vital energies; and there is now no doubt that they
exist in this condition in the air, as do the spores of mucor, aspergillus,
oidium, agaricus, and all other fungi.

Mulder, however, does allow some properties to the yeast vesicle; he says,
"a variety of strange ideas have been entertained respecting the nature of
yeast; recent experiments have convinced me that it undoubtedly is a
cellular plant consisting of isolated cells. They resemble the composition
of cellulose in some respects, but differ from it in many." "These
vesicles, consisting of a substance resembling that of cells, do not
contribute in the least to the fermentation, but are exosmotically
penetrated during fermentation by the protein compound." These chemists
seem to have an instinctive horror of allowing any active properties to the
yeast vesicle, that is as far as the conversion of sugar into carbonic acid
and alcohol is concerned in the act of fermentation. Dr. Carpenter, as if
desiring to conciliate the chemical and physiological disputants, considers
that the truth is to be found in the mean of the two extremes,--that is,
that the process of fermentation is neither entirely dependent on chemical
laws, nor on those laws which preside {113} over the growth of reproductive
matter, but is a process in which both perform certain offices, each
depending on the other to produce the combined result; he thus approaches
more nearly to the theory of Mulder, than that of Liebig.

But to revert to Mulder, he speaks of the Torula cells being "exosmotically
penetrated during the process of fermentation by the protein compound." Now
the Torula is acknowledged to be one of the Fungals, and the chemical
constituents of the Fungi approach very nearly that of animal tissues. They
contain a peculiar principle, residing in and obtainable from them, termed
Fungin, which is as highly azotised as animal fibre. The protein compound
alluded to, Mulder says, is not gluten, because insoluble in boiling
alcohol, and not albumen, because it is very readily dissolved in acetic
acid, and he regards it as a superoxide of protein. This superoxide of
protein can only have been produced by a vital action in the cells of the
Torula, and as the fungi consume oxygen, and give out carbonic acid, we
clearly have all the elementary conditions for their growth in almost all
decomposing animal and vegetable matters. It is the nature of the fungi to
live on organized matter, but always when it has a tendency to decay; it is
for this reason they have been called "Scavengers." Again, we can
understand why some animalized or nitrogenous matter should be necessary
for fermentation, otherwise fungi could not grow, nitrogen being an
essential constituent of {114} their structure, and further fermentation
does not commence without the presence of oxygen, and like as in animals,
this gas supports their existence. The conversion of sugar into alcohol is
represented by the following formula:--

                             RESULT.
              Sugar.  Alcohol.  Carbonic Acid.
  Hydrogen      3        3
  Oxygen        3        1            2
  Carbon        3        2            1

If therefore the process were merely of a chemical nature, where is the
necessity for atmospheric oxygen to accomplish the end? it is quite certain
that fermentation cannot go on without its presence. Let us compare the
action of ferment or yeast in a dried state to the action of albumen, which
Liebig says is sufficient when decomposing to set up fermentation. "The
white of eggs when added to saccharine liquors requires a period of three
weeks, with a temperature of 96° F. before it will excite
fermentation."[42] But any saccharine liquor on exposure to the air, though
entirely destitute of albumen or gluten, will ferment, and the Torula may
be found in it. I have found the Torula in a great variety of syrups which
have spontaneously undergone fermentation. I have also discovered that the
development of the cells is delayed or accelerated by the nature of the
ingredient used in flavouring {115} the syrups, with other peculiarities
which need not here be mentioned.

But the conversion of starch into sugar by means of gluten requires some
notice, as by some persons it is associated in their minds with the organic
process of fermentation.[43] Mulder ascribes the latter in the first
instance to the action of heat, evidently believing that the
pseudo-catalytic operation of gluten upon starch is the type of all such
actions, and regarding them all as simply chemical, but we here distinguish
a wide difference; in the latter instance the gluten is decomposed, and
rendered unfit for a repetition of the chemical phenomenon, and if it is
desired to renew the action fresh gluten must be obtained, and a certain
temperature kept up, otherwise the experiment fails. How different is
fermentation: in the ordinary temperature of the atmosphere the yeast
vesicle will multiply, no incremental or unnatural addition of heat is
requisite, and it is one of the commonest and most natural instances of
vegeto-chemistry: the grape cannot shed its juice, nor the sugar cane its
sap without admitting these germs, which, under certain {116} conditions
multiply themselves and convert the saccharine elements into new compounds.
The method by which the conversion of starch into sugar is accomplished is
thus described by Dr. Ure. He says that if starch one part be boiled with
twelve parts of water and left to itself, water merely being stirred in it
as it evaporates, at the end of a month or two in summer weather it is
changed into sugar and gum, bearing certain proportions to the amount of
starch used. But "if we boil two parts of potato starch into a paste, with
twenty parts of water, mix this paste with one part of the gluten of wheat
flour, and set the mixture for eight hours in a temperature of from 122° to
167° F. the mixture soon loses its pasty character, and becomes by degrees
limpid, transparent, and sweet, passing at the same time first into gum and
then into sugar."--"The residue has lost the faculty of acting upon fresh
portions of starch."

Four points of contrast present themselves for notice as elements of
comparison with true fermentation. 1st. The starch solution has to be
boiled, so that heat, by which it is to be supposed that the starch globule
is ruptured, seems to be an essential portion of the chemical change, and
even this may in fact alone be sufficient in such a case to produce some
elementary change in the starch, and may prepare it for the subsequent
catalytic action of some related organic, though not vital material.[44]
{117} 2nd. Not only a summer heat is necessary, but a period of one or two
months time must elapse before the starch with the water simply becomes
converted into sugar, and if artificial heat is to be used to hasten the
operation, a temperature from 122° to 167° F. must be resorted to in order
to obtain the desired result. 3rd. When even this is accomplished there is
no reproduction of the fermenting matter, and artificial and chemical means
must again be applied to repeat the experiment. 4th. The conversion of
starch into sugar can be accomplished without the presence of gluten at
all, by the aid only of temperature and time. It seems to me, therefore, to
be entirely unnecessary to occupy more space in the elaboration of a proof
of the doctrine that the germs of the Torula are the sole agents in the
conversion of saccharine fluids into alcohol and carbonic acid. By another
chemical process starch can be converted into sugar, but I am not aware
that hitherto any method has been discovered by which sugar can be
converted into alcohol except by the process of fermentation proper.

I have been thus particular in commenting on this subject, as it bears, in
an especial manner, on the question under consideration.

{118}

The physiologist cannot afford to lose this process from the category of
chemico-vital, or biochemical manifestations.[45] The philosophy of the age
has a tendency to make every thing chemical; it is true that the Divinity
is as much seen in the laws which govern the elementary particles of
matter, as in those laws which preside over the transmutation and
sustentation of those elementary and inorganic particles, when compounded
in the tissues which are engaged in the formation of living beings. The
laws by which acids and alkalies neutralize each other, and the affinities
single, double and elective, which the particles of matter exhibit,
together with the influences of light, heat, and electricity upon almost
every condition of matter, are as truly wonderful as the creative power.
Man may, in many instances, imitate the processes of nature, he can render
iron magnetic, and form alkaloids, but the {119} laws which govern the
particles of matter are still the secret of the whole proceedings. We do
but interpret the language of nature in discovery, the book is ever open
before us, and every atom of the world is a word and a theme, capable of
occupying the short span of sublunary existence allotted to man. We have
read of "sermons in stones," but a book has been written on a "pebble."[46]

To return, as we every where in nature find a gradual transition in the
forms, arrangements and properties of matter, so we may expect to find a
link between the inorganic and vital chemistry of nature. The fungi, by
which we contend this transition appears to be accomplished, are also a
link in chemical composition, between the animal and vegetable kingdom, and
not only in that, but in their subsisting upon matter which has been
organized, they are deoxidizers and reducers, as the vegetable kingdom in
its highest function is a compounder. To their functions and offices in the
great scheme of creation, we may fairly apply ourselves with a sure and
certain result of the most interesting discovery. Is it no hint that
wherever decaying organic matter is found, there do we find fungi? is it no
hint that they are found in all parts of the world? that even in snow the
germs of fungi will grow and multiply to such an extent, according to Capt.
Ross, that the protococcus was seen {120} by him, clothing the sides of the
mountains at Baffin's Bay, rising, according to his report, to the height
of several _hundred feet_, and extending to the distance of _eight miles_?

Even stones contain in their interior, or interspaces of their structure,
the germs of fungi. A species of Tufa is found in the vicinity of Naples of
a porous texture, which, when moistened and shaded, produces vast
mushrooms, four or five inches high, and eight or ten inches broad.[47]
This author further says: "In the Maremma, where the volcanic tufa is the
basis of the soil the surface is intermixed with the animal remains of
departed empires, and the ordure of cattle, is covered with grasses of old
pasturages, and is wet with heavy dews. Everything, therefore, conspires
there to a fungiferous end."

They are found growing in and upon both vegetables and animals. Nees von
Esenbeck imagined, that minute forms multiplied themselves in the
atmosphere; and really, when we consider the amount of effluvia composed of
the atoms cast off from the bodies of living or decaying organic matters,
which are incessantly passing into the atmosphere, the conjecture is not an
unreasonable one. The minuteness of those, which we know are always found
growing on decomposing bodies, does not preclude the possibility, nay,
further favours {121} the probability, that others infinitely more
minute,[48] may be destined to remove the more subtle and vaporous
particles which escape into the air.

We can, therefore, I think, conclude, that the lower tribes of vegetation,
may consistently be regarded as capable of existing in almost any
condition, and almost under any circumstances, they may be made to grow in
plants by inoculation, as shewn by De Candolle, and Dr. Hassall. If the
stem of wheat also is inoculated with vibriones, they will make their
appearance in the grain.[49] If the seed contain them and have not lost its
germinating properties, these worms will be found again in the grain. If
the grain containing them be dried for years, and moistened again with
water, these animalcules, according to Bauer and Steinbach, will present
all the phenomena of life. This experiment I have witnessed, and can
confirm the statement. These animalcules in the diseased grain, have under
the microscope the appearance of an immense {122} number of eels crowded
together in a small space, and presenting a movement more, perhaps,
vermicular than any other, and it is continued for a considerable time. Now
if these animalcules, or their ova, can be proved to pass with the sap to
the seed, there can be no difficulty in comprehending how germs,
considerably more minute and of a vegetable nature, should be found subject
to the same peculiar mode of obtaining an entrance into animals and
vegetables for sustenance. "It is usually imagined," says Dr. Carpenter,
"that the germs liberated by one plant are taken up by the roots of others,
and being carried along the current of the sap, are deposited and
developed, where vegetation is most active."

The chemical theory of disease would be better sustained by a comparison of
"the artificial formation of alkaloids," and the phenomena of
transformation of blood into the tissues of animals, and their degeneration
into effete matters, and of sap into the tissues of plants and their
degenerations.

Professor Kopp of Strasburg, says, "In a chemical point of view, the
alkaloids are remarkable for their composition, for their special
properties, both physical and chemical, and for the interesting reactions
to which many of them give rise, when exposed to the influence of different
reagents. Considered medically, the organic bases are distinguished by
their energetic properties. They {123} constitute at the same time, the
most violent and sudden poisons, and the most valuable and heroic
remedies."

Upon this very intricate and interesting part of chemical philosophy, it is
rather dangerous to enter without a thorough and practical knowledge of the
subject. This, however, falls to the lot of few men. We, who are engaged in
the study of disease, and of the best methods of cure, are obliged to take
the investigations of the analytical chemist, and examine them for
ourselves in the intervals of leisure allowed us during the active exercise
of our calling. Though with less advantages for the study of these
transcendental relations of organic and inorganic matter, we are not,
nevertheless, precluded from forming our opinions on their practical
bearings to the phenomena and treatment of disease.

That there is a matter of a poisonous nature concerned in the production of
endemic and epidemic affections, cannot be doubted by any one; I believe
indeed, that the chemical theorists admit this, at all events Liebig does,
for he says, "The morbid poison changes in the blood are fermentative, just
such as occur in beer making." If we start, then, with the consideration
that poisons, in a chemical point of view, are the objects of our research;
the obvious course to take is to enquire what is the source of poisons
generally, and what their effects on the animal economy? The mineral
poisons are entirely excluded from the enquiry by their {124} inaptitude
for diffusion, and their uniform effects upon all persons, differing only
in degree in their operation. The same objections apply to gaseous poisons,
except that to them the property of diffusion would be admitted.[50] We
come then to the alkaloids, which constitute, as Kopp says, the most
violent and sudden poisons. For the production of alkaloids by artificial
means, organic products of some kind are required. Artificial heat,
powerful chemical agents or length of time, are, as far as information at
present extends, the indispensable requirements to induce these peculiar
changes in matter. The only instance I can find, in which elementary
matters can by artificial means be combined, so as to resemble the products
of nature, is that of the conversion of carbon and nitrogen into cyanogen.
But the process by which this is accomplished, leads rather to doubt
whether it be really and simply by a combination of _elementary_ carbon and
nitrogen. I extract the following from the Annual Report of the Progress of
Chemistry, for 1848. "H. Delbruck has performed some experiments on the
important subject of the formation of cyanogen. He confirms the statements
of Desfosses and Fownes, inasmuch as a _weak but distinct_ formation of
cyanogen was observed on igniting {125} _sugar-charcoal_[51] with carbonate
of potassa in an atmosphere of nitrogen." The use of sugar-charcoal, may be
perhaps an explanation of the weak formation of cyanogen, for in these
numerous and successive chemical changes of matter, it is impossible to say
how many sources of error may arise. The constant contradictions of each
other, and the opposite statements made by chemists, of equal eminence,
leave us in a wilderness of doubt, from which we are not likely to be
freed, until definite laws shall be discovered to act as a guide in the
comprehension of the higher branches of Chemical Philosophy.

But supposing that the generation of alkaloids could take place in the
body, or some analogous poisonous matter, we have yet to imagine a whole
host of peculiar and essential conditions to effect this change, besides an
atmospheric agent or agents to set in motion those compositions and
decompositions, capable of bringing out these new products from the
elements of blood. We are aware that in the blood, carbon and nitrogen are
sufficiently abundant as well as saline compounds, to generate cyanides,
and, with hydrogen also there in plenty, hydrocyanates, and thus from them
many other poisonous products, but how is all this to be effected? And even
if effected, it is yet a question if such compounds can in any way simulate
the attacks of epidemic disease. We have {126} already shewn that the
amount of most poisons necessary to destroy an individual, can be pretty
clearly estimated, and their _modus operandi_ is tolerably well understood.
Again, the most essential part, in which all chemical theory fails, is an
explanation of the reproduction of contagious matter.

The catalytic process, by which decompositions are said to be effected, and
in which Liebig includes the various fermentations, is one of those
chemical relations of matter to matter, considered by some as the probable
cause of infection. Mr. Simon, in a late lecture, has said, "I consider the
phenomena of infective diseases, to be essentially chemical, and I look to
chemistry to enlighten the darkness of their pathology. Qualitative
modifications, affecting the molecules of matter as to their modes of
action and reaction, are such as form the subject of chemical science; and
those humoral changes which arise as the result of infection clearly fall
within the terms of its definitions." Further on he adds: "The phenomena of
infected diseases appears then, in many respects, to be sui generis.
Certainly they are chemical. _Probably_ they belong to that _class_ of
chemical actions called _catalytic_."[52]

{127}

It is not improbable that something resembling a catalytic action may take
place in the blood in those diseases of endemic and epidemic origin, but
that it can be by a chemical process alone is contrary to all experience of
catalytic operations, for except in the instance of fermentation proper,
there is no multiplication of the fermentative matter. The action of the
matter of contagion seems to stand on the confines between electro-chemical
and bio-chemical manifestations, and so long as no chemical explanation can
be given for the multiplication of the matter of infection, the most
rational course to adopt is to assume that life under some unknown form is,
as we every where find it, the sole reproductive agent.

       *       *       *       *       *

{128}

SECTION II.

THE ANIMALCULAR THEORY OF EPIDEMICS UNTENABLE.

The animalcular theory of disease, after remaining almost unnoticed for
nearly two centuries, has been again revived under the auspices of Dr.
Holland in this country, and Henle of Berlin. And though not entirely
buried in obscurity, this theory had completely failed to modify the
practice of physicians in the treatment of those diseases which were
supposed to owe their existence to these invisible atoms of created being.
The resuscitated notions and all their amplifications, to which the advance
of science has contributed so much, are threatened with a like fate, an
absence of all practical results.

Though I would not attempt to deny the possibility, nay, even the
probability, that insect life may yet be discovered as the cause of some
diseases,[53] still {129} there are many and cogent reasons against both,
and which are at variance with facts and observations. Where insect life
has been found associated with disease, it more especially appears as a
consequence than as a cause.

Disease, in its most enlarged sense, is a conversion of one form of matter
into another; it is a transformation of healthy blood and tissue into new
and abnormal products. Where insects in all their variety of forms are
discovered, their voracious propensities are their chief characteristics,
they are the consumers of matter after its partial disintegration, if
animal matter be their food, unless they be carnivorous and predacious, or
if herbivorous they usually feed upon the tender shoots of plants. Thus far
we are certain of the manner in which insects destroy living matter; it is
a process the unassisted eye may every where witness, and which experience
has amply attested. To take, however, the animalcular world as it presents
itself to us under the microscope, and as the intermediate step between the
manifest and the hidden for a fairer and more direct method of reaching the
truth, what do we observe to be the ruling law of infusory instinct? They
live to feed; the term polygastrica sufficiently implies their natural
tendency to consume. The simplest form of animalcular life, seen in the
genera of monads, still preserves the animal character by possessing a
stomach or stomachs in which the food is received, to be digested for the
nourishment of the {130} system; and even some of these minute objects
which vary in size from one _two-thousandth_, to one _three-thousandth_ of
a line in diameter, are said to be carnivorous and predacious. Upon this
fact alone, I would place the improbability of insects being the cause of
epidemic disease. Each insect doubtless has its own peculiar food, and
whether it be a vegetable or animal feeder, it consumes the matter already
organized for conversion into its own tissue, and the only change which
could be affected by them in the blood, would necessarily be that of
appropriation of some one of the constituents as an element of food; when
that food is digested, (taking digestion generally as an identical
process,) the excrementitious matter is composed of secretions and
disorganized matter, mixed together as an _effete_ product, and destined
then for reorganization by the vegetable kingdom. Now all animals, whether
they be large or small, live on organized matter,--they convert that matter
into an inorganic form, and I cannot help imagining that if epidemic
diseases and fevers depended upon animalcular growth and development in the
blood or tissues of the body, the excretions or secretions from them would
have yielded some information to the searching enquiries of the chemist,
supposing that these excretions and secretions were capable of reaching to
a sufficient amount in quantity, to bring about those fatal effects of
poisoning, we witness in Cholera and other epidemic affections. Insects, I
{131} believe are poisonous only by their secretions, and though they are
known to multiply with exceeding rapidity, I can hardly imagine that by
their development, however rapid, they could produce such a change in the
human body, as to bring about the speedy dissolution, and generally
gangrenous appearance, that has invariably been observed in those suddenly
dying under the influence of epidemic poisons. The vibriones, whose
destructive effects on wheat are so well known, are a genus of animalcules,
which at first would seem to favour the animalcular theory in a remarkable
manner; for on examining them, they do not appear to possess any other
structure than a gelatinous absorbing mass, in this respect resembling a
vegetable.

But Ehrenberg's scrutiny corrected the error of De Blanville, and shewed,
that they were far from being agastria, or stomachless animals. The Rev.
William Kirby says, "Ehrenberg has studied the vibriones in almost every
climate, and has discovered, by keeping them in coloured waters, that they
are not the simple animals that Lamarck and others supposed, and that
almost all have a mouth and digestive organs, and that numbers of them have
many stomachs." All the discoveries indeed which have been made on the
minuter forms of animal life, have tended to confirm the doctrine that the
stomach is the exponent organ of an animal; that is, in all animals there
exists, in a variety of modified conditions, a receptacle for food. Some of
the {132} animalcules, however, are still supposed to exist by absorption,
as the vinegar eel, _vibrio anguilla_,[54] but when we find that the law
is, generally speaking, that the receptacles of food become multiplied in
number in these minute beings, and the vibriones which were supposed to be
stomachless, have been proved to emulate their associates in the number of
these organs; it would be more reasonable to conclude that our imperfect
vision is the barrier to their detection, rather than to suppose that they
do not exist. Besides, when we are told on undoubted authority that some of
the animals of this class, have as many as _forty or fifty_ stomachs; the
least we can do, is to allow that all of them possess, at least one
digestive organ, though we may not be able to detect it.[55]

So far then for the consideration of animalcular structure: let us now more
particularly enquire into their destructive habits, and their functions,
inasmuch {133} as they may be supposed capable of engendering epidemic
diseases and fever. The truly carnivorous animalcules, or those truly
herbivorous in their instincts, we may presume to be beyond the limits of
our enquiry. We have rather to do with those which take an intermediate
position, namely, those which feed upon matter undergoing decomposition, or
upon fluids containing organic matters in solution, or suspension. If we
take Entozoa generally, they may be considered as most conveniently to be
placed in this intermediate class; and here we find still the digestive
apparatus, and more than this,--for upon the modifications of the organs
appropriated to digestion is their classification founded. "Rudolphi
divided the Entozoa into Sterelmintha, or those in which the nutrient tubes
without anal outlet are simply excavated in the general parenchyma, and
into the Coelelmintha, in which an intestinal canal with proper parietes
floats in a distinct abdominal cavity, and has a separate outlet for the
excrements."[56]

How do these animals obtain their sustenance, and what changes can they
produce upon the vital fluid of the body? Analogy is here our only guide.
If the trichina spiralis is examined, it is found to be enclosed in a cyst
containing fluid; and this is, {134} doubtless, the source of its
nutriment, and contains in solution the elements for its nutrition; but in
this instance there is no selection, and there can be no locomotion to an
extent sufficient to imply searching for food, as the animalcule in its
natural state, when taken from the human muscle, is found coiled upon
itself, making about two and a half turns. The fluid of the cyst is thus in
all likelihood prepared by endosmosis, for the immediate and appropriate
nutrition of the parasite. The cyst is thus the part which performs the
diseased process, the containing animalcule is merely the consumer of what
is prepared for it by the cyst. And this would seem to be the rule with all
parasites, of the encysted kind.

We have alluded to the vibriones which are found in the fluids of living
bodies, and the trichina which is found in the solid muscle; we have now to
refer to those which infest the cavities. It was, I believe, Ehrenberg, who
shewed that the tartar which accumulates on the teeth is composed of the
debris of minute animalcules; in fact, that it consists of calcareous
matter, having once formed a portion of the structure of their bodies, the
ubiquity of these creatures is therefore as much and clearly established as
the lower forms of vegetation. The intestinal worms, of which perhaps the
Tænia is the most curious and important to be noticed, are from the
locality in which they are found, chiefly injurious by the irritation they
set up, and by appropriating {135} to themselves the nutrient juices
elaborated in the process of animal digestion, thus depriving the
individuals they infest of that which was destined for their own
nourishment. In this, as in all associated instances, the character by
which these parasitic animals are marked is their consuming propensity.
There is, however, one more observation to make upon parasitic growths; but
the question is yet unsettled in what kingdom of nature is the
acephalocyst, or hydatid, to be placed. Mr. Owen says, "As the best
observers agree in stating, that the acephalocyst is impassive under the
application of stimuli of any kind, and manifests no contractile power,
either partial or general, save such as results from elasticity, in short,
neither feels nor moves, it cannot, as the animal kingdom is at present
characterized, be referred to that division of organic nature."

We thus arrive at the simple cell, and the multiplication of living beings
by cell buds; it is the point at which the confines of the animal kingdom
are reached, and at which we are driven to speculation. The hydatid lives
like a plant, by imbibition; and procreates, like a plant, by budding,
either endogenously or exogenously, as regards the original or parent
cell.[57]

{136}

This condition of being, suggested the notion of Protozoa, or first
animals, in the same way that the purely cellular plants, that is, each
individual, consisting of a single cell, gave the idea of Protophyta, or
first plants. Mr. Kirby thus expresses himself on this subject: "The first
plants, and the first animals, are scarcely more than animated molecules,
and appear analogues of each other; and those above them in each kingdom
represent jointed fibrils."

Admitting, then, that animals as well as plants exist in the form of simple
cells, and that their multiplication proceeds apparently upon the same
principle in each, it is nevertheless abundantly manifest, that the
cellular form of perfect individuals is infinitely more numerous in the
vegetable than in the animal kingdom.

{137}

From the mosses downwards to the fungi, the whole structure of the plants
consists of an aggregation of cells, more or less in number and complicate
arrangement, until, through a variety of gradations, we reach the single
cell as a perfect individual.

It is rather remarkable, that the lower forms of vegetables and animals
seem to derive their nutriment from matter of a similar kind; and though
the office of plants is as a rule, to convert inorganic into organized
matter, it appears that some of the fungi may live as animals do on organic
matter when in a state of solution. This, however, is uncertain; for we do
not know what are the first signs of decomposition in organized bodies, and
for aught we can tell, it may be perpetually going on; so far as the
disengagement of carbon from the system is concerned, this is certain; but
whether the nitrogenous compounds also are subject to a resolution into
their elements in the living body, is another question, and not so easy of
solution. The partially decomposed elements of animal structures are,
however, particularly adapted for the nutrition of the lower forms of
vegetation; it is, indeed, from the decaying organic matters that the fungi
derive, it may be said, their entire food.

       *       *       *       *       *

{138}

SECTION III.

SKETCH OF THE PHYSIOLOGY AND PATHOLOGY OF PLANTS AND ANIMALS.

Animals and plants depend for their existence upon a nutritive fluid, which
permeates their structure; it is the element from which all their
secretions are formed, and their organs are nourished.

The food of animals is composed of previously organized matters, and is
conveyed into a reservoir called a stomach, where it undergoes a process of
solution, previously to entering the circulation. At this period, the
animal and the plant again present points of resemblance, the lymphatics or
absorbent vessels take up the products of digestion, and convey them to the
blood-vessels, where mingling with the current of the blood, they are
conveyed to the lungs, there to undergo a process of oxygenation before
they become fitted for the renovation of the tissues of the body. Such is
the nature of the food of man, that it contains all the elements necessary
and adapted for transformation into bone, muscle, brain, and parenchyma, as
well as the other tissues of the body; besides other elementary matters,
which, though they form a very insignificant portion of {139} animal
textures, from their constant presence in the vital fluid, evidently
perform some important offices in the general economy of life; they are
partly, perhaps, occupied in forming constituents of secretions.

Plants do not require a stomach,--the humus or soil to which they are fixed
is the laboratory, where the nutritive matter is prepared in a state fit
for absorption by the spongioles of their roots, and these correspond to
the lymphatics of animals; after being taken up by the spongioles, this new
fluid mingles with the sap, and passes to the leaves or breathing apparatus
of plants, where carbonic acid gas combines with the crude vital liquid,
and converts it into a condition fit for all the offices to be performed by
the plant: viz. the growth of tissues, and the elaboration of secretions.

The tissues, however, of plants, though more simple in their nature,
present a much more varied character than those of animals, when the
different species are compared.

The bones of animals which give them their form, are invariably constituted
of phosphate and carbonate of lime, deposited in a matrix of gluten;
muscle, nerve, brain, tendons, and ligaments, have nearly, if not
completely, an identical composition throughout the whole range of the
animal kingdom: their secretions, however, vary much more considerably, as
also do the secretions of vegetables. But vegetable tissue may contain, as
in the stems of {140} grasses, a considerable amount of silex, and some
notable quantity of sulphur, and so essential to their existence is the
former element, that they cannot live without its presence in the soil, and
also with it an alkali, to render it soluble. A large amount of soda, is an
invariable attendant upon the structure of marine plants, as potash is of
those growing on the land.

Thus, whether we regard the health of animals, or vegetables, we discover,
that besides the matters which are absolutely indispensable for the
nutriment of the tissues which undergo rapid transformation, those of a
more permanent and durable nature require in an almost insensible degree, a
restitution of elements; and though not apparently absolutely necessary to
preserve vitality in the being, yet have so marked an influence over it, as
to indicate an extensive bearing of each individual part, on the whole
associated entity.

The elementary tissues of both kingdoms have been traced, in whatever form
they may be found, to a cellular origin. The minutest vegetable germ, is a
cell containing a granular matter within it, and even man himself, in his
embryonic state, may be represented as an insignificant point in the realms
of space; and might be placed side by side with the smallest particle of
living matter, without suffering by the comparison.

The laws by which the development of these elementary cells is regulated,
so that each advances {141} to its limit, and fulfils its destination, is
one of those inscrutable and overwhelming mysteries of nature, which leads
the admirer of creation on and on into the abyss of the future, and fills
his soul with aspirations for that time, when the veil of ignorance shall
be withdrawn. But this is not my subject.

The organization of the two animated kingdoms, is then regulated by
definite laws, and all matter, whether acting upon them as agents of
nutrition or destruction, are equally under their dominion; to investigate
and to endeavour to fathom some of these laws, is the aim I have in view.

The sap is to the plant, what the blood is to the animal,--the elements of
nutrition and secretion are contained in it, and whatever interferes with
its normal constitution by subtracting from, or adding to it, deteriorates
its qualities, and retards or accelerates the functions of the individual.
Excess or deficiency of the natural elements may also be a source of
disturbance; if carbonic acid be too abundantly liberated in the soil, as
Dr. Lindley expresses it, "plants become gorged;" and if, on the other
hand, the elimination be too slow, they become starved. It has been also
shewn, that plants though they give out oxygen from their leaves, do not
throw it off as animals do carbonic acid from their lungs; but that this
arises as a result of digestion, and the fixation of carbon in the system,
and that they really respire oxygen as {142} animals do, and give off
carbonic acid, both by day and night.

That light is the stimulant of the digestive functions, and that,
therefore, during the day, the amount of oxygen thrown off, far exceeds the
amount of carbonic acid liberated during the same period.

The great and important distinction between animals and plants is, that the
former possess a nervous system, by which they are subject to a very
extended series of psychological relations; it is in these chiefly, if not
entirely, that we are to look for the distinctive and well-marked
differences of diseased action. In animals there are special media of
communication between the sources of dynamic power, and the parts upon
which the force is exercised: and again, a return communication exists,
which conveys impressions to the source of power, and to use a simple
comparison, a system of telegraphing is in incessant and watchful
operation. This force is influenced and modified in its action, when
exercised in the regulation of nutrition, growth, and reproduction of
tissues, by the passions and emotions of the mind. All the secretions and
functions of the body are more or less susceptible of being accelerated,
retarded or modified by the psychical relations of mind and matter. Though
we are apt to imagine that in man alone, these phenomena obtain much
importance--there can be but little doubt, that wherever a {143} nervous
system exists, whether in the form of aggregated or diffused ganglia, the
interdependence of force and organization, each upon the other, bears a
certain and definite physiological comparison; the more aggregated the
ganglia, the more close, intimate, and extensive the psychical connexions,
and the gradations pass downwards, until they appear to be lost on the
confines of the vegetable kingdom.

The diseases of plants and animals deserve a more careful comparison than,
I think, has hitherto been bestowed upon them.[58] If the study of
physiology, or an enquiry into the laws which regulate the functions of
living beings in a state of health, has been materially aided by the
intimate knowledge of vegetable physiology, which, from the simple
structure of plants, so favours the experiments of the student, there is
every reason to suppose that vegetable pathology may also lead us to an
equally important and useful result.

It is quite certain, that if a healthy seed, or leaf-bud, be placed in such
a situation, that, according to the laws known, it will in all likelihood
germinate, if all the elements for its sustenance exist in the soil, and
the temperature and hygrometric {144} condition of the atmosphere are
adapted to it, a healthy plant will be the result. Light, heat, moisture,
and soil are therefore to be considered as the agents required to exist in
a certain balance, or proportion, in reference to the health or power of
vitality of the plant. Within a certain amount of variation, health may
persist in virtue of the power of selection, which appertains to the
spongioles of the root in absorbing nutriment; and also as regards light,
from the tendency which most plants have to accommodate themselves to any
deficiency of this element, by presenting their leafy expansion in that
direction where the most of its influence may be obtained. But beyond a
certain limit an unhealthy condition sets in. If the soil contain not the
inorganic elements, which are absolutely indispensable for the tissues of
the plant, or even if they be there and not in a state to be absorbed, a
dwindling and degeneration ensue; if light be deficient in quantity,
pallor, feebleness, and elongation of tissue follow, with more fluidity and
general softness of texture. These conditions of plants have their
analogues in the ill-fed and ill-nourished children in some of our
manufacturing districts; they are stunted and diseased. Transport a healthy
country lad, with the bloom of health on his cheek, from his native hills
and valleys, or woods and fields, to the stool behind a desk for eight
hours a day, in a narrow street in any city, where the rays of the sun
rarely penetrate, it will not be long before {145} the skin of the animal
and the cuticle of the plant may be submitted for comparison, when both
will testify to the importance of the solar rays, as an indispensable agent
in supporting the normal processes of organic life. So far common
observation is competent to a solution of the facts; but beyond this we
come to the enquiry, what resemblances are there in the early conditions of
plants and animals. Each originates from nucleated cells, endowed by the
All-seeing Power with a blind impulse of progressive development; the most
simple cell of a vegetable multiplies itself by a generation of new cells
within it, when the parent dies, and liberates the offspring. Here
progression is simply multiplication; it is, as it were, progression in
length only. The original cell, however, of animals, which is styled the
germinal vesicle, extends or becomes developed into dissimilar parts; and
whatever may be the variety, all alike proceed from the original germ cell,
and the _tout ensemble_ of parts constitutes the one and indivisible whole;
in this instance there is addition besides multiplication, tissues and
organs are added in all variety, until the maximum of organic development
is attained in the wonderful being, man.

Yet how many points of resemblance are there between the vegetable cell and
the fully developed human being, in a physiological and pathological point
of view. There must be nourishment to sustain both; both require a certain
amount of light {146} and heat for their growth and increase, and are
dependent upon various unknown causes for active and healthy existence; and
when a certain time has expired, all alike return to a condition, in which
the particles composing them are subject only to the dominion of the laws
which preside over inorganic matter.

But during the existence of plants and animals, we discover other features
of comparison; plants, as well as animals, are liable to disease; they are
subject to functional and organic affections. The former, among plants, are
usually traceable to atmospheric vicissitudes or irregularities, changes of
situation, &c.; and in man to irregularities of diet, and mental and bodily
excesses, as well as to atmospheric vicissitudes.[59]

The organic diseases of plants and animals depend upon a repetition, or
continuance, of functional derangement. As a consequence of this, the
nutrition and reproduction of tissues lose their normal and definite
character, wherefrom an indefinite and abnormal result is obtained. There
is a limit to abnormal productions, and they are apparently {147} subject
to laws, though not yet understood. In animals, they may be either
excessive development of natural tissue in natural localities, as obesity
and fatty tumours; they may be natural products in unnatural situations, as
fatty degenerations of muscular tissue; or altogether new and unnatural
products, as tubercle and cancer.

In plants, from their greater simplicity of structure, organic affections
are perhaps entirely limited to the two first forms of animal organic
disease; viz. to undue development of tissue in natural situations, and to
the formation of natural tissue in parts of a plant where they are not
usually found in a state of nature. The variety of excrescences seen on the
stems, branches, and twigs of plants, may be given as instances of the
former; and the conversion of stamina into petals, as in double flowers, as
an instance of the latter.

We derive our sustenance from vegetables, and they from us; they produce
for us the soothing opiate and the deadly strychnia; we for them the
animating ammonia, and the distortions and sterility of excessive culture;
we engender in them, by the latter, debility, disease, and death; and in
our turn we become their prey. All this indeed is but a cycle of events,
that requires no learned mind to fathom, and to comprehend; it is a matter
of every day occurrence, and, though perhaps not entirely unheeded, is not
dwelt upon in the fulness of its bearings and importance. {148}

Let us now consider the diseases of plants, as a study progressive to those
of man; and as their physiology has so extensively served us, we may
possibly also find in their pathology much material for instruction; not
that it will be attempted to shew that the same diseases affect both
kingdoms, but that diseases, though dissimilar in effects, may have similar
sources.

Unfortunately, there are not many men in this country, who need go further
than their own gardens to find abundance of disease among their fruit trees
and vegetables. The vine, the apple and the potato, common to most gardens,
will furnish specimens.

It is an error of a serious kind to suppose, that the parasites which
infest plants are not essentially the cause, or, perhaps, more properly
speaking, the elements of disease. I confine myself here to disease of
parasitic origin, as that is the subject of which I am chiefly treating.

That parasitic growths are the elements of disease in some instances, is
now beyond dispute. The experiments of Mr. Hassall, detailed in Part II. of
the Transactions of the Microscopical Society of London, are most
conclusive; and they are of that simple nature, that any one may convince
himself of their accuracy, by a repetition of them from the directions
there laid down.

He says, the decay is communicable at will "to any fruits of the apple and
peach kind, no matter {149} how strong their vital energies may be, by the
simple act of inoculation of the sound fruit with a portion of decayed
matter, containing filaments of the fungi. We may use with success the
sporules of such fungi; but in this case the decomposition does not set in
so quickly; in the one case, the smaller filaments of the fungi have
advanced several stages in their growth; while in the other, the sporules
have yet to pass through the several stages of their development."

Mr. Hassan, however, seems to speak doubtfully as to the mode in which the
disease becomes naturally introduced;[60] how the spores enter the fruit,
"is not very clear--though probably, it is by insinuating themselves
between the cells of which the cuticle is composed, or perhaps by means of
the stomata, where they are present. I may here state that the experiments
were made on fruit, while living, and attached to the tree."

But why should there be a doubt as to the parts by which the sporules of
minute fungi enter the plant, when it is clear, that not only can they
enter {150} by the spongioles, but by the stomata of the leaves, and mingle
with the sap. It is true, that they make their appearance and grow upon the
leaves and the fruit; but these are the situations most adapted for their
fructification. I have seen the spores of the fungi which attack the
cucumber and vegetable-marrow, in the cells of the hairs, and even their
filamentous prolongations; these appropriate the fluids conveyed to the
cells of the hair, rupture them, and at length fructify.

On referring to Dr. Lindley's Medical and Economic Botany, I find that many
fungi are the active elements of disease, and in a manner which renders it
highly improbable that they are so in any other way, than by obtaining an
entrance to the sap of the plants. Of the microscopic fungus which destroys
wheat, the Uredo caries of De Candolle, we find the habitat to be within
the ovary of the corn, and that 4,000,000 may be contained in a grain of
wheat,--now this and another fungus, the Lanosa nivalis, are said to
destroy whole crops of corn: we cannot imagine that such an extensive
affection, can have any other source than by means of the spores through
the sap, seeing that bruising of the surface, or rupture of the cuticle of
the apple, a comparatively soft fruit is necessary to produce the disease
artificially in them; besides, a grain of corn containing vibriones, when
grown and having fruited, the new fruit also contains them--now here, as
this is I believe almost invariably the {151} case, either they or their
ova must be carried with the sap to the new germs.

It is rather a remarkable fact, that these entophytes appropriate the
nutriment destined for the plant in which they grow, they are consequently
the means in many instances of its entire destruction, though only
partially so in others.

There are many Fungi which have this tendency. The Puccinia gramienis,
"preys upon the juices of plants, and prevents the grain from swelling."
The Æcidium urticæ, common on nettles, deprives the plant on which it
grows, of the organizable matter, intended for its own nutrition. The
Erysiphe communis, overruns and destroys peas. The Botrytis infestans,
"attacks the leaves and stems of potatoes." The Oidium abortifaciens,
attacks the ovaries of grasses--and the Oidium Tuckeri, "a formidable
parasite, destroys the functions of the skin, of the parts it attacks." The
latter has been most injurious to the vines, during the last two years. I
have known instances in which the vines have been cut down, and every means
taken to rid the houses of the disease; but this year, it has made its
appearance, with all its former virulence, in the new shoots.

This, however, is sufficient to shew that plants are liable to disease,
depending upon parasitic growths, which affect their vital powers, and
deprive them of their natural nutritive fluids.

But somewhat similar diseases belong also to {152} warm climates; in a
letter from Cuba, dated Dec. 1843,--Mr. Bastian writes, "_a plague_ has
appeared among the orange trees--a mildew attacking the leaves and the
blossoms, which finally dry up. It most frequently kills the trees. None of
the orange family are exempt; lemons, limes, and their varieties, with the
shaddock and forbidden fruit, have all suffered." This disease has
continued without intermission, till the present year,--when the same
gentleman writes, Feb. 20th, 1850: "The evil exists, although in a
diminished degree, so much so, as to have allowed the trees to produce me
30,000 oranges again. In old times, the same plantations produced me
100,000."

The West India sugar-canes are also liable to a disease, which the Rev. Mr.
Griffiths, in his Natural History of the Island of Barbadoes, speaks of, in
the following manner: "This, among diseases peculiar to canes, as among
those which happen to men, too justly claims the horrible precedence." This
disease is called the Yellow Blast. It is difficult to distinguish the
Blast in its infancy, from the effect of dry weather.

There are often seen on such sickly canes, many small protuberant knobs, of
a soft downy substance. It is likewise observable, that such blades will be
full of brownish decaying spots. The disease is very destructive to the
canes. It is observed, that the Blast usually appears successively in the
same fields, and often in the very same spot of land. {153}

This Blast is often found far from "infected places," and the infection
always spreads faster to the leeward, or with the wind.

"_It is remarkable if canes_ have been once infected with the Blast,
although they afterwards to all appearance, seem to recover; yet the juice
of such canes will neither afford so much sugar, nor so good of its kind,
as if obtained from canes which were never infected."

I may here allude to the circumstance, that in the island of Cuba, the
destructive mildew is commonly called, _la pesta_.

It were needless to multiply instances of other endemic and epidemic
diseases of vegetables; they are well known by practical observers to be
very numerous, and I believe, in most instances, depending upon fungoid
growths. The destruction of vegetables by insects, is of a very different
nature to that produced by the fungi; it would be as unreasonable to
consider the consumption of corn and herbage by locusts, as a disease of
vegetation, as the massacre and devouring of human beings by cannibals, a
disease of the human body.

It is true that insects are exceedingly destructive to plants, but as far
as I am able to obtain information, they appear to be so chiefly by their
voracious propensities; they consume the structure of the plant in its
entity, and do not primarily interfere with its vitality. The instance of
the vibriones, before-mentioned, seems at first to be an exception {154} to
the rule, but this is rather apparent, than real; and it may be made to
apply more as a confirmation, than an obstacle to the vegetable theory: for
if we may fairly compare the diseases of animals with those of plants, the
existence of entozoa in the latter, would be considered an essential point
to be substantiated.

Having now considered the question as to the infeasibility of supposing
that chemical fermentation is the basis upon which a theory of diseases can
be sustained, and having shewn that life is inseparable from infection, and
miasmatic generation;--having explained the phenomena of the dispersion of
diseases by comparison with the dispersion of plants, and finally, having
demonstrated that the physiology and pathology of plants bear so close a
relation to each other, and that their epidemic affections depend upon
minute organic germs, I submit to the judgment of my readers, whether there
is not much reasonableness in the application of the facts to the
inference--that living germs are the cause of epidemic disease in man and
animals.

       *       *       *       *       *


{155}

CHAPTER IV.

RESULTS IN PROOF OF THE TENABLENESS OF THE PROPOSITION.

--------

SECTION I.

OBSERVATIONS ON SOME OF THE LAWS OF EPIDEMIC DISEASES.

The results obtained by comparing certain facts connected with Epidemic
Affections of animals, with analogous affections in plants, afford, from
the few instances I shall here notice, a very strong presumption, that
analogous causes operate in the production of these affections. I have
already quoted from Hecker, to shew that previously to, and during the
Epidemics of the Middle Ages, the minuter forms of animal and vegetable
life appeared to be called into existence, much more abundantly than usual;
that famines prevailed in consequence of failure of cereal crops, no doubt
depending then, as now, upon the various forms of fungiferous growth. I
cannot refrain quoting here, a passage or two from our old friend Virgil;
for he confirms not only the fact of peculiar showers in {156} connexion
with diseases, but he also refers to the rust of corn, thus:

  150. "Mox et frumentis labor additus; ut mala culmos
  Esset rubigo ...
  ... Intereunt segetes."

  _Georg. 1._

Then:

  311. "Quid tempestates autumni et sidera dicam?

    .    .    .    .    .    .

  322. "Sæpe etiam[61] immensum coelo venit agmen aquarum
  Et foedam glomerant tempestatem imbribus atris
  Collectæ ex alto nubes."

  _Georg. 1._

The occurrence of black showers in this country has been observed during
the present year, and I understand that in the fenny countries of the East,
the corn has suffered much from the Uredo. I am not mentioning the
circumstances as cause and effect, but merely to call attention to the
fact, that unusual phenomena of this kind have been generally associated
with disease of the animal and vegetable tribes.

The same causes also predispose plants as well as animals, to epidemic
attacks of disease. The repeated observations in the public journals on the
subject of ventilation, drainage, and over-crowding, render all notice from
me needless, to shew that these, though they do not produce the diseases
{157} treated of, yet that under the influence of bad air, bad drainage,
and over-crowding, epidemics are fostered and spread.

Lastly, says the Count Philippo Ré, "I would remark that if _bad
cultivation, and especially bad drainage, does not produce bunt or smut, it
is certain that those fields, the worst treated in these respects, suffer
the most from these diseases_."

It has been remarked by many observers, that a greater fecundity has
attended upon Pestilences, and this has been proved by comparison, that the
births in proportion have far exceeded the ordinary limit.[62] In
juxtaposition with this observation, I will place the following, not as a
proof, but as a remark made quite independently of the subject of which I
am treating. "From the first the diseased ears are larger than the healthy
ones, and are sooner matured. What appears singular, but which I have not,
perhaps, sufficiently verified, is _that the seeds are more abundant than
in a sound ear_."

{158}

Now these are facts which require amplification, and if these two alone
should be shewn upon an extensive field of observation, to apply not only
to corn, but to other members of the vegetable kingdom, as I doubt not will
be the case, though I am not fully prepared to prove it, it would be
difficult to dissociate the fertility of the two living kingdoms from the
operations of one and the same, or an analogous law.

The epidemic diseases of plants are both infectious and contagious, at
times they are observed to be endemic only, and then depending particularly
upon some local causes. This is a law of diseases which applies equally to
those of men and animals. In connexion with this law is another, which, as
far as I am aware, has not hitherto been noticed in connexion with plants.
The potato disease, which excited so much interest and created so much
anxiety for the poorer classes of society, led the Government of this
country to employ the most learned men to investigate the subject, in the
hope of propounding some reasons which should explain the cause of the
calamity, and thereby deduce a method of eradicating the evil, or, in other
words, discover a cure for the disease. Many were the opinions as to the
cause of the distemper, which it were useless here to recount, but a method
was suggested, to which most people, I believe, looked forward with great
anticipations, and this was to obtain native seed, and to sow it on virgin
soil. Was the end accomplished? No. {159} For though the seed was sown, and
the plants grew, the disease still appeared among the newly imported
individuals, to as great an extent, as among the native or domesticated
plants.

As a parallel to this, it may be stated, that, as regards either endemic or
epidemic disease, those persons newly arrived, either in a district or
country where these prevail, are even more liable to them than the
residents.[63] Again, I have learned, that where the potato disease has
been so bad as to render the crop almost valueless, the best plan to be
adopted is, to allow the plants to remain in the earth, and thus leave such
as retain their germinating powers to come up spontaneously the following
year. I certainly saw one large field treated in this way, yield a crop
almost without disease.

{160}

The seasoning, in this instance, seems to bear a comparison with the
seasoning of animals and man, under a variety of diseases, which for a time
renders them insusceptible of another attack. It therefore does not appear
so improbable, that these affections may be regarded, as Unger, the German
botanist supposed, the Exanthemata, or Eruptive Fevers of vegetables.

Another feature seems to associate the Epidemics of plants and animals, in
a manner suggestive of analogous causes operating in both instances.

The lungs of animals and the leaves of vegetables, are their respiratory
organs, by means of which, the blood in the one case and the sap in the
other, derive gas from the air, and impart gas to it, each taking what is
thrown off by the other.

Now the epidemics among vegetables, have a remarkable tendency to exhibit
their effects primarily on the leaves, and particularly on those parts
which are appropriated to the function of respiration. It is from the
stomates that many of the fungi commence to germinate, and their
fructification may be seen sprouting from the opening composed of a chink,
surrounded by a peculiar arrangement of cells, which constitute the
breathing apparatus of their victim.

In the earlier epidemics, of which we read, one of the most remarkable
circumstances, was the extraordinary influence the poisonous matter
appeared to {161} exercise over the lungs,[64] and they again, were the
means of propagating the disease, and spreading the contagious particles
through the atmosphere, for we read: "Thus did the plague rage in Avignon
for six or eight weeks, and the pestilential breath of the sick, who
expectorated blood, caused a terrible contagion far and near, for even the
vicinity of those who had fallen ill of plague was certain death; so that
parents abandoned their infected children, and all the ties of kindred were
dissolved."[65] "The like was seen in Egypt. Here also inflammation of the
lungs was predominant." "Here too the _breath_ of the sick spread a deadly
contagion."

It is more than probable that all infectious matter obtains an entrance to
the system through the lungs. Inspiring the air containing the pestilential
semina is, indeed, the only plausible explanation of infection; for though
the skin is indubitably an absorbing {162} surface, and capable of taking
up and conveying to the blood any noxious matter applied to it, yet it is
far more probable that the lungs would effect this process with greater
rapidity. Then the stomach, the only other absorbing surface to which
extraneous matter can be applied, is not likely to be the part where the
elements of disease would obtain an entrance to the system, for many facts
prove, that infectious matter may be swallowed without any injurious
consequences, unless in a very concentrated state. Instances are not easily
found of diseased matter having been swallowed, except where diseased
vegetables have formed under some combination of circumstances, a portion
of diet.[66]

Many facts are on record which prove the powerful effect of diseased grain
when made into bread, and taken for any length time as a principal article
of food. The history of Ergot of Rye is too fresh in the memory of most
people to require more than an allusion here. The stomach had no power over
the secale, its poisonous properties were retained, after having been
submitted to the digestive process, as was evidenced by the abortions and
gangrenes it occasioned.

But diseased wheat is also capable of inducing {163} gangrene, and it is
more than probable, that many diseases might be traced to the use of
infected grain of various kinds. An interesting account of a family who
lived at Wattisham, near Stowmarket, in Suffolk, and all of whom suffered
more or less from living on bread made of smutty wheat, may be found in the
Philosophical Transactions. The mother of this family and five of the
children, consisting of three girls and two boys, all suffered from
gangrene of the extremities; the father lost the nails from his hands, and
had ulceration of two of his fingers.[67] Dr. Woollaston wrote thus in a
letter on this case: "The corn with which they made their bread was
certainly very bad: it was wheat that had been cut in a rainy season, and
had lain on the ground till many of the grains were black and totally
decayed, but many other poor families in the same village made use of the
same corn without receiving any injury from it. One man lost the use of his
arm for some time, and still imagines himself that he was afflicted with
the same disorder as Downing's family." It is not unlikely this was the
case, for numbness and loss of power was one of the well marked characters
of the disease.

What other afflictions may be due to diseased vegetation and adulterated
articles of food, and what loss of life may accrue from cheap and
adulterated {164} drugs and chemicals is hardly yet dreamt of.[68] The
systematic practice of adulteration of almost every article of diet which
comes to table has become a serious question for the legislature to
consider. Take only the article of milk, upon which the young children of
large towns and cities, make their chief meals, with the addition of bread.
How much milk comes into London from the country, how much is obtained from
stall and grain-fed cows in the metropolis, and how much is said to be
consumed, would be an interesting calculation. It is pretty well known that
a mixture is sold by which a retailer of milk may increase his supply by
one-third or one-half. It was discovered in Paris that the brains of
animals, when prepared in a particular manner, formed, when mixed with a
certain proportion of milk and water, a very fine and deceptive cream; in
that city this system was carried on to a considerable extent. I could not
help alluding to these facts while speaking of diseased grain, for who
shall say to what extent a miller in a large way of business, may be able
to "work in," as it is called, a considerable amount of smutty corn in the
manufacture of flour? Now, as diseased grain is known {165} to induce
abortion, it is impossible to tell how small a portion may in some cases
produce the effect; we may therefore say with Thomas of Malmesbury, "There
is no action of man in this life which is not the beginning of so long a
chain of consequences, as that no human providence is high enough to give
us a prospect to the end."[69]

To return,--associated with these observations are other facts of
considerable weight. Before and during pestilences, abortions are more
frequent than in ordinary times; infectious and contagious diseases induce
abortion; besides this, and independently of disease, conditions of the
atmosphere have been known to exist when abortion has been an epidemic
affection; of this Dr. Copland says, "to certain states of the atmosphere
only can be attributed those frequent abortions sometimes observed which
have even assumed an epidemic form, and of which Hippocrates, Fischer,
Tessier, Desormeaux, and others have made mention." With this reference I
will close the subject of comparison between the affections of the
breathing apparatus in animals and plants, merely alluding to the
probability that under some conditions of atmosphere, independently of
heat, &c. vegetables without any other assignable cause will become
abortive.

       *       *       *       *       *

{166}

SECTION II.

WHAT IS THE NATURE OF THOSE POISONS WHICH MOST RESEMBLE THE MORBID POISONS
IN THEIR EFFECTS ON THE BODY?

In the early part of this book, I considered the nature of poisons
generally, and had occasion to remark upon the characters which separated
poisons into two distinct classes. 1st, Those which have the power of self
multiplication; and 2nd, Those destitute of this property.

Of the first we have seen that the poisons of epidemic diseases multiply
both in and out of the body.

The poisons of infectious diseases, not usually epidemic, do the same.
Those of endemic affections, such as ague and some fevers, usually become
multiplied out of the body only, but under some circumstances, and peculiar
atmospheric conditions, they may be also multiplied within the body. The
amount of these poisons necessary to produce their specific effects, may be
inappreciable. Of the second class, there are two kinds, those derived from
the organic kingdom and those derived from the inorganic kingdom. Of these,
the amount necessary to produce their specific effects is appreciable and
pretty well known.

But among those poisons, consisting of organic {167} products, there is one
which seems to hold an intermediate place. This is derived from one of the
Fungals, and as it takes this remarkable position as a link of connexion
between the two classes of poisons, I may be excused quoting a passage of
some length upon this agent, from Dr. Lindley's Vegetable Kingdom. "One of
the most poisonous of our fungi, is the Amanita muscaria, so called from
its power of killing flies, when steeped in milk. Even this is eaten in
Kamchatka, with no other than intoxicating effects, according to the
following account by Langsdorf, as translated by Greville. This variety of
Amanita muscaria, is used by the inhabitants of the north-eastern parts of
Asia in the same manner as wine, brandy, arrack, opium, &c. is by other
nations."--"The most singular effect of the amanita is the influence it
possesses over the urine. It is said, that from time immemorial, the
inhabitants have known that the fungus imparts an intoxicating quality to
that secretion, which _continues for a considerable time after taking it_.
For instance, a man moderately intoxicated to-day, will by the next morning
have slept himself sober, but (as is the custom) by taking a teacup of his
urine, he will be _more powerfully intoxicated_ than he was the preceding
day. It is, therefore, not uncommon for confirmed drunkards to preserve
their urine, as a precious liquor against a scarcity of the fungus. The
intoxicating property of the urine _is capable of_ {168} _being
propagated_; for every one who partakes of it has his urine similarly
affected. Thus with a very few amanitæ, a party of drunkards may keep up
their debauch for a week."

This property of the amanita, at once places it in a separate category from
all other organic poisons, it has yet to be shewn upon what this
intoxicating fungus depends for its activity. Whether some secretion is
formed in the tissue of the plant, or whether some new arrangement of the
particles of matter or modification of the sporules, is brought about by
entering the system, it is impossible to say. Langsdorf states that the
small deep-coloured specimens of amanita, and thickly covered with warts,
are said to be more powerful than those of a larger size and paler colour.
As the effect is not produced until from one to two hours after swallowing
the bolus, and as a pleasant intoxication may be obtained by this agent for
a whole day, and from one dose only, there is a defined line between this
and the ordinary narcotics and stimulants in common use. That the digestive
powers of the stomach have no influence over the intoxicating properties of
the plant, is manifested in the fact, that the active principle passes into
the urine, not only not deteriorated but apparently increased, for, as we
have seen, a teacup of the urine from a man, intoxicated by taking the
amanita into his stomach, will cause him to be more powerfully intoxicated
than by the {169} original dose. We have, therefore, but two conjectures
left for consideration, either the original intoxicating principle is
excreted from the system in a condensed form, in which case its
indestructibility by digestion, makes it approach the ordinary organic
poisons, or there must be an increase of the toxic agent, in which case we
must suppose a reproductive process having taken place in the system.
"There is," says Dr. Mitchell, "in the wild regions of our western country,
a disease called the _milk sickness_, the _trembles_, the _tires_, the
_slows_, the _stiff-joints_, the _puking fever_, _&c._" The animals
affected with this disease, "stray irregularly, apparently without motive;"
they lose their power of attention, and finally tremble, stagger, and die.
"When other animals--men, dogs, cats, poultry, crows, buzzards, and hogs,
drink the milk or eat the flesh of a diseased cow, they suffer in a
somewhat similar manner." This disease is attributed by Dr. Mitchell to the
animals having grazed on pasture contaminated with mildew, and the
resemblance to the effects of the amanita, together with the persistence of
the specific principle within the fluids and tissues of the body, render it
more than probable that to some fungoid growth, is due the peculiar toxic
effects here noticed. Further: "The animals made sick by the beef of the
first one, have been in their turn the cause of a like affection in others;
so that three or four have thus fallen victims successively." De Graaf
states, that butter {170} made from the milk of diseased cows, though
heated until it caught fire, did not lose its deleterious properties. The
urine of diseased animals, collected and reduced by evaporation, produced
the characteristic symptoms. All these facts point to some peculiarity in
the properties of matter not yet investigated or at least not explained. If
we may assume that reproduction is here an element of the persistence and
apparent multiplication of active matter, I know only of one instance to
compare with it. A gentleman about to deliver a lecture on the properties
of arsenic, and its history generally, made two solutions of a given
quantity of arsenious acid, in the following manner. He took a certain
amount of distilled water, and the same of filtered Thames water, and made
his solutions of arsenic by separate boilings, he then as soon as possible
placed the liquids in identical bottles, carefully prepared for their
reception. In the one which contained the arsenic boiled in river water,
the hygrocrocis is now growing, while that boiled in distilled water
remains perfectly limpid and free from any vegetable production. There can
scarcely be a doubt, that the filtration of river water was not
sufficiently purifying to remove the minute spores of some lower forms of
vegetation, which not only live in arsenic but have resisted the
temperature employed in boiling an arsenical solution to saturation.

As to the first class, or truly reproductive and {171} morbid poisons, the
most heterogenous ideas have from all time existed. I have introduced the
notice of the above poisons, viz. the Amanita, and that which engenders the
milk sickness, to compare the results of the morbid poisons on the human
body with them, and also to associate them with the effects of diseased
grain. From the Amanita and that other fungoid matter which is said to
produce the milk sickness, there appears to be a purely toxic action on the
system, but in the instance of diseased grain, a blood disease, ending in
gangrene, or a specific and peculiar action of the generative organs is the
consequence, and where the latter occurs, the poison usually expends itself
on these parts, either by inducing abortion, or augmenting the catamenial
secretion.

Now, the morbid poisons, if studied only in their results, shew that there
is a combination of these two actions. There is usually, in the first
place, a toxic or poisonous action, and secondly, a deteriorating or
decomposing action on the blood, by which there is a tendency to low or
asthenic inflammation and gangrene. It matters not what form of fever we
take as an illustration, whether intermittent, pestilential, or
exanthematous, either will serve the purpose of shewing how completely the
effects of vegetable organic poisons resemble those which for the sake of
distinction (I suppose) have been denominated Morbid Poisons.

Take an attack from the paludal poison. It is {172} usually ushered in with
head-ache, weariness, pains in the limbs, and thirst, with other symptoms;
all these are indicative of a poisonous agent in the blood: then come the
full phenomena of the disease at a longer or shorter interval, and tending
ultimately to destroy some organ of the body. The mind suffers during the
course of the attack, and delirium occasionally happens. In severe cases of
this disease, which were more frequent formerly than now, coma, delirium,
and frenzy were observed at the commencement of the attack, and a tendency
to rapid disorganization of one or several of the viscera.

If we take the effects of poison of Erysipelas, of Scarlet Fever, or
Plague, in each we find at the onset more or less general derangement of
the system, usually with cerebral disturbance and disordered action of all
the dynamic forces of the body, which clearly indicate the action of a
poison; then, unless some favourable symptoms arise, the blood exhibits a
steady advance towards disorganization, and sphacelation of one or more
tissues or parts of the body ensues. In Erysipelas the force of the
diseased action is expended on the skin, and subcutaneous cellular tissue;
in Scarlet Fever the fauces ulcerate, and slough and the parotids
suppurate; in the Plague there is a general tendency to putrefaction, and
the formation of glandular abscesses with sphacelas. Without going any
further into this matter, for my present intention is merely to draw {173}
notice to certain facts, let me now ask, whether or not, do the poisons of
the Ergot, the Uredo, and the Amanita, exhibit more analogy in their action
on the nervous system, the blood and the tissues, than any other poisonous
agents with which we are acquainted? If the whole range of the lower fungi
could be examined in reference to their operation on the blood, as
decomposers of organic compounds,--if experiments could be made, by which
the properties of fungoid matter could be detected, I would venture to say
the whole of the phenomena of these diseases could be readily comprehended
and their intricacies unravelled.

We know that the fungi are poisonous, that at times and seasons, and under
variations of climate, they vary in their effects, and perhaps lose
altogether these properties. We know that the fungi produce gangrene of the
tissues, and disorganization of the blood; we know that their spores
pervade the atmosphere, and are ready, under favouring conditions, to
increase and multiply; we know that they are ubiquitous, and that those
conditions most favourable to their development, are exactly such as are
proved to foster and engender disease, and above all, they have been proved
to be the elements of some diseases in man, in animals, and in plants. Can
as much be said of any other known agents, animate or inanimate, comprised
in our category?

It has been said, we do not see after death,--the {174} interlacing
mycilium, or the sprouting pileus; therefore the fungi are not the agents
of disease--it has been said that carbonic acid and alcohol are not found
as products of diseased action--consequently disease is not a fermentative
process. "In all cases," says Liebig, "where the strictest investigation
has failed to demonstrate the presence of organic beings in the contagion
of a miasm, or contagious disease, the hypothesis that such beings have
cooperated, or do cooperate in the morbid process, must be rejected as
totally void of foundation and support." Much as I admire the genius of
this great man, it is difficult to refrain from remarking, that I doubt if
any of his great discoveries would have been made, if, in the first
instance, hypotheses had not formed the basis of all his researches. It has
been said, "that casual conjunctions in chemistry, gave us most of our
valuable discoveries:" and it is from casual conjunctions that hypotheses
are usually formed, the working out proves either their fallacy or their
truth, but to say that an hypothesis has no foundation, until demonstrated
to be true, is rather knocking down argument. And who, let me ask, has been
more prolific of hypotheses than our continental neighbour? Yet he,
according to his mode of reasoning, would sweep away all such words from
the vocabularies of philosophers. What foundation has the chemical
hypothesis of disease, when it fails to explain the most important element
{175} of contagious and infectious diseases: viz. the reproductive property
of their germs?

It is perhaps necessary to say something in explanation of the sudden
deaths arising from morbid poisons. They may occur from two causes. One
being the result of a concentrated amount of poison germs being inhaled
into the lungs, and acting as an ordinary toxic agent; and the other, which
I put only hypothetically, the consequence of the rapid evolution of gas in
the vessels arising from a sudden decomposition of blood, as it passes
through the lungs. The only authority I have for this supposition, is the
fact that the blood after death, from pestilential affections, is found to
be far advanced towards decomposition; that in Paris last year, two
patients were bled while suffering from Cholera, and with the small
quantity of blood which flowed, bubbles of air also escaped:[70] and
besides this, it was demonstrated by Mr. Herapath, that ammonia was given
off from Cholera patients, both by the lungs and skin. These facts, though
they are not conclusive, nevertheless render it probable that such an
explanation is not entirely out of reason--especially too, when we know how
fatal are the effects of uncombined air, when it enters the vessels near to
the heart.

       *       *       *       *       *

{176}

SECTION III.

WHAT RESULTS DO WE OBTAIN FROM THE EFFECTS OF REMEDIAL AGENTS, IN PROOF OF
THE HYPOTHESIS?

I have here used the word hypothesis, because, having so far advanced in
the enquiry, I trust sufficient has been said to render the term
applicable.

Under the term remedial agents, I shall include all those causes, whether
natural or artificial, which tend to neutralize or destroy the germs of
infection, or miasmatic poison, whether this be effected out of or within
the body.

First, then, let us consider the results of drainage and cultivation in
removing the causes of endemic disease. One well authenticated case is as
good as a thousand. I will take one, which, from its source, will be
received as unexceptionable; and from its association with a very learned
and amusing book, will be accepted as an agreeable reminder of the many
pleasant hours spent in the perusal of the poet Southey's "Doctor."

"Doncaster is built upon a peninsula, or ridge of land, about a mile
across, having a gentle slope from east to west, and bounded on the west by
the river; this ridge is composed of three strata; to wit, of the alluvial
soil deposited by the river in former {177} ages, and of limestone on the
north and west; and of sandstone to the south and east. To the south of
this neck of land, lies a tract called Potteric Carr, which is much below
the level of the river, and was a morass, or range of fens when our Doctor
first took up his abode in Doncaster. This tract extends about four miles
in length, and nearly three in breadth, and the security which it afforded
against an attack on that side, while the river protected the peninsula by
its semicircular bend on the other, was evidently one reason why the Romans
fixed upon the site of Doncaster for a station. In Brockett's Glossary of
North Country words, Carr is interpreted to mean 'flat marshy land,' 'a
pool or lake;' but the etymology of the word is yet to be discovered.

"These fens were drained and enclosed pursuant to an Act of Parliament,
which was obtained for that purpose in the year 1766. Three principal
drains were then cut, fourteen feet wide, and about four miles long, into
which the water was conducted from every part of the Carr southward, to the
little river Torne, at Rossington Bridge, whence it flows into the Trent.
Before these drainings, the ground was liable to frequent inundations; and
about the centre there was a decoy for wild ducks; there is still a deep
water there of considerable extent, in which very large pike and eels are
found. The soil, which was so boggy at first that horses were lost in
attempting to drink at the drains, has been brought {178} into good
cultivation, (as all such ground may be) to the great improvement of the
district; for till this improvement was effected, _intermittent fevers and
sore throats were prevalent there, and they have ceased from the time the
land was drained_. The most unhealthy season now, is the spring, when cold
winds, from the north and north-east, usually prevail during some six
weeks; at other times Doncaster is considered to be a healthy place. It has
been observed that when endemic(?) diseases arrive there, they uniformly
come from the south; and that the state of the weather may be foretold from
a knowledge of what it has been at a given time in London, making an
allowance of about three days, for the chance of winds. Here, as in all
places which lie upon a great and frequented road, the transmission of
disease has been greatly facilitated by the increase of travelling."

I feel certain of being excused for transcribing this long passage from
Southey. It would have been impossible to convey its whole meaning without
giving it entire. The continuation of the chapter is no less instructive
and applicable to our subject, though more particularly so to an extension
of the enquiry. The sore throats and intermittents, from which Doncaster
has been freed, by the drainage of Potteric Carr, informs us at once that
decomposing matter is the material by which the poison of fever is vivified
and sustained, the wet and boggy state of the soil is just the condition,
when no drainage exists, to bring into activity the germs of {179} disease,
which otherwise would lie latent. So satisfied and acquainted are we with
the elements necessary for the production of fever, that we might as
certainly bring about an endemic intermittent by forming an artificial bog,
as we could be sure of growing mushrooms by making a bed in the manner laid
down by gardeners for this purpose. Dr. Lindley also says, "the _Polyporus
fomentarius_ has been artificially produced in Germany, but merely by
placing wood in a favourable situation, and keeping it well moistened. Five
or six crops were obtained in the year."

Let warmth, moisture, darkness, and decaying matter be given, and inanimate
disintegrated particles will soon be converted into definite forms and
combinations instinct with life. It is by the unseen forms of living
beings, that the atmosphere is preserved from becoming charged with deadly
gases; they take the first rank in the great scheme of animated beings, the
plant first, and then the animal. "Let the earth bring forth grass." "Let
there be lights in the firmament." "Let the waters bring forth the moving
creature, and fowl that may fly," and "Let the earth bring forth the
cattle, the creeping thing, and the beast." This is the order of creation,
of living things, and the earth was prepared by vegetation for the animal
world. The work of conversion is accomplished by vegetation; and this is
consumed for the construction of higher organizations.

The laws which govern and control the universe, {180} are as definite and
as wonderful among invisible atoms, as those which regulate the enormous
masses floating in space; and the time will come when the advancing
intellect of man will measure and weigh the morbid poisons, as he measures
and weighs the stars. Why should the laws of Epidemics be less understood,
than the laws which govern the course of comets? The aspirations of man
have led him to penetrate the heavens, which charm and inspire him; he
studies rather the more violent disturbing elements of nature, the
thunder-cloud and the fire of heaven, than the silent pestilence which
steals over the earth. I cannot conceive it possible that the Intellects,
which are occupied in procuring means for the Majesty of this empire to
issue her mandates with the velocity of a spirit to the nethermost parts of
the earth, should be incapable of solving so deeply interesting a mystery
as the causes and nature of pestilential diseases. It would seem that man
prefers to issue a mandate of destruction many thousand miles distant, than
to disarm the pestilence at his door. It is barely a century since Galvani
observed the twitchings in the muscles of a frog's leg, and the battery,
still named after him, has already become an agent of instantaneous
communication between places many miles distant. But how many centuries
have passed away, each one succeeding the other, with its millions of
victims to epidemics? And where are the remedies for the evils? Drainage
and cleanliness, with all their advantages, were better understood and more
fully carried out by the ancient {181} Romans than by ourselves; there are
monuments, though crumbling to decay, to tell us of the vast enterprise of
these people and of the value they set upon a healthy and vigorous
constitution, and how well they understood the means of warding of disease.

Cultivation and drainage are now fully understood to be the basis by which
a healthy condition of air is to be obtained, next to that, cleanliness and
ventilation; if either be neglected a sickly, mouldy, and unwholesome
contamination of atmosphere ensues; the odour of a bog is proverbially
mouldy, and so is that of an ill-ventilated house or cellar; dryness, or
the fresh pleasant scent of clean water, are the antagonists of these; the
aromatic odours of vegetation are opponents of putrefaction, and
consequently of the development of the lower forms of life. All
empyreumatic matters prevent mouldiness and decomposition; and odours
arrest and prevent the growth of mouldiness. The oil of birch, with which
the Russia leather is impregnated, and which gives it so pleasant an odour,
effectually prevents mouldiness, and consequently decay.

Lindley says, "It is a most remarkable circumstance, and one which
_deserves particular enquiry_, that the growth of the _minute fungi_, which
constitute what is called mouldiness, is _effectually prevented_ by any
kind of perfume."[71] Cedar has {182} been used, from time immemorial, for
a like purpose; and I doubt not the recommendation of Virgil, before
quoted, in reference to the burning of cedar, was founded on some practical
utility of this kind, though its _modus operandi_ was unknown to him.
Allied to these is a curious circumstance, and worthy attention. I copy the
following from an old work on Pestilences. "It is remarkable that when the
Plague raged in London, Bucklersbury, which stood in the very heart of the
city, was free from that distemper; the reason given for it is, that it was
chiefly inhabited by druggists and apothecaries, the scent of whose drugs
kept away the infection, which were so unnatural to the pestilential
insects, that they were killed or driven away by the strong smell of some
sorts of them." "The smell of _rue_, and the smoke of tobacco, were
prescribed as remedies against the infection; but especially tar and pitch
barrels, which it was imagined preserved Limehouse, and some of the
dock-yards from infection."[72]

Pitch and tar dealers are everywhere spoken of as being remarkably exempt
from infectious diseases.

Cold infusion of tar was used in our colonies as a prophylactic against the
Small Pox. Bishop {183} Berkeley was induced to try it when this disease
raged in his neighbourhood. The trial fully answered expectation--for all
those who took tar-water, either escaped the disease, or had it very
slightly.

Tan yards and places in the immediate vicinity, are said to be free from
pestilences. The tanners of Bermondsey are said to have escaped the Plague
of London, and one person only died in Gutter Lane, where was a tan yard.
The tanners of Rome are also stated to have been free from Plague. Dr.
McLean refers to the exemption of tanners at Cairo. _Tannin is prejudicial
to most vegetables_,--but Dr. Lindley says it is not always so to fungi. "A
species of Rhizomorpha is often developed in tan pits." I should imagine
that neither plants nor insects would be found very abundantly, where
tannin prevails; yet we find that the gall-nut is formed for the protection
of an insect from injury by weather, and as a temporary means of
sustenance.

The custom of fumigating with odoriferous substances, does not therefore
appear upon this view of the matter to be destitute of importance; indeed,
the universal practice stamps it at once, as an efficacious remedy for the
purposes of disinfection. The introduction of chlorine fumigation, seems to
have superseded, in a great measure, the use of fragrant herbs and woods;
and it is questionable whether the substitution be altogether desirable or
{184} advantageous. Many scents may be agreeably and usefully employed,
with much less chance of annoyance to the patient, and considerably less
injury to articles of furniture, &c.

The fumigations of sulphurous acid and chlorine are, perhaps, more adapted
as disinfectants in uninhabited apartments;--their power to destroy
vegetation, is well known. They have been used, chiefly, with the idea of
neutralizing gaseous exhalations, particularly chlorine, as it tends to
combine with hydrogen, to form hydrochloric acid, and then to unite with
ammoniacal matters, forming hydrochlorate of ammonia. This, supposing
noxious or pestilential effluvia consisted of the ammoniacal exudations
variously combined, was an exceedingly efficacious method of rendering them
inert; but as we feel convinced that no ammoniacal compound could possibly
be the cause of infection, we must look to the influence these gases
possess over other forms of matter, and as they are so destructive, even in
minute quantities, to vegetable existence, it is possible that their
beneficial effects may be due to this property. The immediate neighbourhood
of gas works is prejudicial to vegetation, I imagine, from the amount of
sulphurous vapours, and to this has been attributed the exemption of
persons employed in these works. Many other instances might be cited of a
similar nature.

I have now to speak of medicinal agents, and here comes a considerable
difficulty. {185}

If we might believe all that has been written on the sure and certain
remedies for the "ills that man is heir to," we should be led to
acknowledge that both nature and art were prodigal in antidotes and
specifics. The all-bountiful hand of nature, I do not doubt, has at the
same time scattered the seeds of good and of evil. The fertilizing showers
fall to irrigate the soil, and produce food and nourishment to man; here
and there is the reeking morass "feeding unnatural vegetation," and if man
takes up his abode in its vicinity, the rains which made it unhealthy, have
also made it highly fertile; by labour and cultivation he may convert the
mephitic bog into a waving corn-field, and the seeds of life and sustenance
be made to supplant the seeds of death and corruption.

It is generally believed, that where there are particular and specific
diseases, there also may be found appropriate and specific remedies; the
discoveries of chemistry, it is not improbable, may in some respects have
retarded the progress of natural medicine. In the early ages of the world,
the "healing plant" must have formed the staple of medical commerce, for
though Tubal Cain[73] has been considered as the first surgical instrument
maker, because he was the first artificer in brass and iron, we have not
discovered that chemical compounds entered into the composition of physic,
till very {186} many years after his time. To the alchemists we owe the
science of chemistry, and much of the physic of the present day may be
traced to them. The multiplicity of ingredients which at one time entered
into the composition of one dose of physic could only be spoken of under
the title of "legion." Who shall specify the active and curative ingredient
(if there be one), when from five to a hundred may have been exhibited at
the same time? It has been the pride of our physicians, that the
pharmacopoeia has been simplified; it has not reached its most simple form
yet. That many simple plants have specific and wonderful power over
disease, is an indubitable fact, but I firmly believe that the laudable,
though mistaken efforts of physicians to improve their effect by various
combinations, have been the means of throwing many valuable medicines into
oblivion; I must also add, that cheap physic and adulterations have had no
small share too in the banishment of much valuable physic from ordinary
practice. It has been believed, and I think with much reason, that a
thorough search into the qualities of plants, would shew that "they are
capable of affording not only great relief, but also effectual and specific
remedies." "That they are not already found, is rather an argument that we
have not been sufficiently inquisitive, than that there are no such plants
endued with these virtues."

Of the result obtained by medical treatment, in cases of epidemic or
infectious disease, it is most {187} difficult to speak, but as my province
here is only to shew that living germs are the morbific agents, I have but
to refer to such remedies as have been most extolled in controlling these
affections. The disinfectants have already been mentioned in a cursory
manner. An enumeration only of simple medicines used during the late
Epidemic, shall conclude this work, as the treatment in former times could
not by any possibility furnish satisfactory information. Aromatics and
fragrant stimulants have in all times taken the foremost rank with acids,
such as vinegar, lime and lemon juice. Mr. Guthrie's adoption of lemon
juice in preference to bark, which he said made him worse while suffering
from an attack of fever, during the Peninsular campaign, and his speedy
recovery from the disease, though not from its effects, shews, when many
others can bear equal testimony to its value, that such a remedy though
simple is not to be despised.

But to the late Epidemic. Dr. Stevens' saline treatment, appears, on the
whole, to have been the most successful. Common salt was used both
medically and dietetically, and formed the greatest bulk of the medicine
employed. Chlorate of potash and carbonate of soda were added to the
medicine.

The nitro-hydrochloric acid was used with success at St. Thomas's Hospital.

Dr. Copland used chlorate of potash, bicarb. soda, hydrochloric, ether, and
camphor water.

Dr. Ayre's calomel treatment had as many, if {188} not more, opponents than
advocates. Phosphorus had several advocates.

Creasote and camphor were lauded by some. The beneficial operation of all
these remedies might be explained on the theory here supposed, that living
germs are the cause of Epidemic disease, but the specific action of any one
remedy has not yet had sufficient attention or trial to enable me to make
any deductions of a satisfactory or conclusive nature.

In the uncertainty which generally prevailed as to the best method of
treating Cholera patients, I was induced (for reasons stated in a pamphlet
published last year) to try the efficacy of sulphur, which had been
extolled as a specific. In its effects I was not disappointed; but as the
results are already before the public, I need not do more than refer to it
among other remedies.

I did not contemplate even alluding to this subject, as it would extend far
beyond my intended limits. This portion of the enquiry would be more
properly carried out by keeping records of cases, treated in accordance
with the view attempted to be established, and I have not the slightest
hesitation in saying, that the most ample success would ultimately attend a
well directed practice, based upon the principles inculcated in these
pages.

       *       *       *       *       *


{189}

CONCLUSION.

In making the foregoing sketch, I have attempted to put together some ideas
on a subject, which has for the last few years been a theme for meditation
in leisure hours, viz. What are the causes of Epidemic, Endemic, and
Infectious Diseases? The occurrence of Epidemic Cholera last year in this
country, awakened a spirit of enquiry. Where there is unrest, whatever may
be the cause, there also is disquiet and discontent. When the oracles of
the age were consulted in the emergency, the discordant answers perplexed
and confused the anxious searcher after truth. In the spring of last year,
when the enemy was approaching, unseen and unheard, and the thousands of
unconscious victims, who are now lying in their graves, were faithfully
trusting and fully relying on the heads of our profession, and the
resources of our art, what was the state of our defences, and what the
nature or character of our resistance? One considerable body of men would
discharge from a little tube of glass, a host of almost invisible globular
atoms of sugar, said to be as potent and inscrutably operative as the
unseen enemy. These infinitesimal practitioners assured the people that
they "_had powerful means of subduing the disease_," {190} but even they
differed among themselves, though they carried out to the fullest extent
the doctrine of their leader, _similia similibus_, which we may suppose to
refer in this case to the minuteness of the opposing armamenta. Without,
however, agreeing with this school, I may quote a passage from Dr. Curie,
which is, alas! too true: "We have shewn, as they must (allopathists), and
many of them do acknowledge, that they have no fixed basis, no natural law
upon which their treatment rests."

Who can deny the force of this observation? Sheltered by a principle, it
matters not how fallacious, a man is placed as behind a barrier. If with
any reason it could be shewn that the infinitesimal doses, could by no
possibility effect a cure in Cholera; if it could be demonstrated by any
line of argument, that a poison, a living poison, circulates with the
blood, or lodges in the tissues, the homæopathist must fall; his
"electricity and mineral magnetism," and "_powerful concentration of life
power towards the digestive canal_," will stand for what they are worth.
That minute doses of medicine can exert an active influence over the body
is not to be denied, but these must consist of powerful drugs, as arnica,
aconite, and nux vomica, with others, and it is more than probable, that of
such medicines, an inconceivably small amount may produce a specific effect
upon some portion of the organic nervous system.

How is it that a dose of nitre or digitalis, "can {191} convert
cheerfulness into low spirits," or a grain of red sulphuret of antimony,
"excite warmth and lively spirits?"[74]

Why should indigo dyers become melancholy, and scarlet dyers choleric?[75]
We do not know. But there is one thing we most certainly do know, that a
poison may be disarmed by an antidote, and the amount of the latter must be
in proportion to that of the former, and as epidemic and contagious
diseases do most unquestionably depend upon poisons of a specific nature,
and of great amount and activity, an infinitesimal remedy, however it may
claim to direct and control the organic forces, under slight and ordinary
disturbances, can be no more effectual in destroying the poison of fever,
or small pox, than in neutralizing arsenic or prussic acid.

The uncertainty which generally prevails as to the treatment of Epidemic
diseases, Fevers, &c. induced me to put together the notions which are
contained in these pages, in the hope of leading to some definite ideas of
the causes of these affections, and consequently to a more uniform and
scientific mode of treating them.

I have endeavoured to shew that reproduction is a phenomenon inseparable
from morbific matter, and that in all probability the vegetable kingdom is
the source of the germs.

{192}

The train of argument adopted is such as appeared to me most natural for
such an enquiry, and it rests now only with those who are capable of
deciding whether such a course, though (I am sensibly aware) not without
many faults in conception and execution, is calculated to advance the
science of medicine and the interests of mankind.

The real tree of knowledge, possesses in the spongioles of its roots, an
elective property, by which truth alone can enter; nourished and sustained
by this, it sends a fragrant incense and breathing odour on high, and
dispels the mists of ignorance and superstition. In natural causes and
reasonable deductions we must seek for instruction and solid information,
for in over-straining either nature or art, deformity and error must
inevitably be the result.

THE END.

NORMAN AND SKEEN, PRINTERS, MAIDEN LANE, COVENT GARDEN.

       *       *       *       *       *


NOTES

[1] "It matters little how vague and false hypotheses may appear at first:
experiment will gradually reduce and correct them, and all that is
required, is industry to elaborate the proof, and impartiality to secure it
from distortion."--_Sewell_ "On the Cultivation of the Intellect."

[2] It is stated by Mr. Crosse, of Norwich, that vaccination was adopted in
Denmark, and made compulsory in 1800. After the year 1808 Small Pox no
longer existed there, and was a thing totally unknown; whereas during the
twelve years preceding the introduction of the preventive disease, 5,500
persons died of the Small Pox in Copenhagen alone.--_Dr. Watson's
Lectures._

Dr. Blick, an intelligent Danish physician, corroborated the above
statement to Dr. Watson himself in the year 1838.

[3] Philosophy of Life, Lecture 6, translated by the Rev. A. J. W.
Morrison, M.A.

[4] The following I quote from Dr. Fuller on Small Pox and Measles:--

"To this purpose some (and particularly Kircherus) are of opinion that
animalcules have been the causes of malignant and pestilential fevers in
epidemic times, which differ in essence and symptoms, according to the
nature and venoms of those creatures.

"Thus the atmosphere and air is filled both from above and beneath with
innumerable millions of millions of species or corpuscles, aporrhoeas,
steams, vapours, fumes, dust, little insects, &c. all which make it such a
wonderful chaotic compost of things that contains the _seeds_ of good and
evil to man as surpasseth the understanding (as I suppose) of even the
highest order of archangels."

[5] I learn from an undoubted authority that the cow when "slack of health"
eats with avidity the "field parsley;" the sheep under similar
circumstances seeks the ivy, and the goat the plantain.

From an equally good source I have the following: that rabbits and hares,
when they are what is commonly called _pot-gutted_, seek the green broom,
though at a distance of _twenty miles_.

[6] "My settled opinion is, that in regard every effect is necessarily such
as its cause; it must needs be that every sort of venomous fevers is
produced by its proper and peculiar species of virus.

"And that the manner and symptoms of every such fever is not so much from
the particular constitution of the sick; as from the different nature and
genius of their specific venom which caused them.

"And I conceive that venomous febrile matters differ not in degree of
intenseness only, but in essence and _toto genere_ also; and that venomous
fevers are for the most part contagious."--_Thomas Fuller, M. D. 1730._
"Another important class of organic poisons are those which when introduced
in almost inappreciable quantities into the system, seem to increase in
quantity; and which when communicated in the same inappreciable quantity
from the individual poisoned to one who is healthy, excite the same series
of febrile phenomena and local inflammation, and the same increase in the
quantity of the poisonous agent."--_Med. Chir. Review._

"This unseen influence working in the body, presents very striking
analogies to the modes of operation of different poisons."--_Dr. Ormerod on
Continued Fever._

[7] I am aware that the vesicle does not here strictly bear the relation to
the original germ, supposing one active particle alone to be sufficient for
its production, that the egg does to the bird, for in the former case
multitudes of active particles may have been generated from one. I have,
therefore, merely used this expression to signify an aggregation of vital
forces, such as may be imagined to exist in the bird.

[8] "At an early period the form of the ovisacs is usually elliptical, and
their size extremely minute,--their long diameter measuring in the ox no
more than 1/562 of an inch, so that a cubic inch would contain nearly two
hundred millions of them. They are _at this time_ quite distinct from the
_stroma_ of the ovarium; this forms a cavity in which they are loosely
embedded."

[9] Coleridge, p. 56.

[10] "All vegetables," says Sharon Turner, "from that pettiness which
escapes our natural sight, to that magnitude which we feel to be gigantic,
have these properties in common with all animals--organization; an interior
power of progressive growth, a principle of life, with many phenomena that
resemble irritability, excitability, and susceptibility, and a
self-reproductive and multiplying faculty."--_Sharon Turner's Sacred
History._

[11] "Plants highly sensitive to light are those of the leguminous, or Pea
kind. They always close up in the evening and clasp their two upper
surfaces together, presenting only their backs to the air. Plants of
pinnated leaves, as the Tansy, are more sensible than these to the effects
of light. They fold up when light is too strong, as in Robinia; it produces
the same effect as want of light. Its leaves close up, apparently, because
they are receiving too much. So they do if a hot iron be brought near them.
They contract as if to avoid the heat. Sensitive plants, and those of the
Oxalis Lent. are so sensitive that the least motion, even a breath of air,
will make them close."--_Sir J. Smith._

"The vitality of plants seems to depend upon the existence of an
irritability, which although far inferior to that of animals, is
nevertheless of an analogous character."--_Lindley's Introduction to
Botany._

[12] Provincial Medical and Surgical Journal. July 10th, 1850. No. xiv. p.
367. "Practical Observations on the Vaccination Question." By E. Oke
Spooner, M. R. C. S., Blandford.

"If we examine the Cow Pox and the Small Pox microscopically, as I have
done very carefully in every stage, we find that the essential character
consists of a number of minute cells, not exceeding the 10,000th part of an
inch in diameter, being about one-fourth smaller than the globules of the
blood, containing _within their circumference many still more minute
nuclei, and presenting_ beyond their circumference bud-like cells of the
same size and character as those contained within the circle. They exactly
resemble in everything except the size, the globules of the yeast plant,
the Torula Cerevesiæ. Now if we examine more circumstantially the analogies
of what I would call the Torula Variolæ with the Torula Cerevesiæ, we
observe the following corresponding facts.

"What do we accomplish by inoculation as it is called? Simply this. We take
on the top of a lancet, or an ivory point, a few of these minute cells or
germs, and we put them _in their appropriate nidus_, the subcuticular
tissue, where, after a few days if they find their appropriate nutrient
elements, they grow and multiply."

Simon, Chemistry of Man, vol. i. p. 127. "Macgregor ascertained that the
air expired by persons ill of confluent Small Pox, contained as much as
_eight_ per cent of carbonic acid, and in proportion as health was restored
the percentage was diminished to its natural standard." Carbonic acid is
also produced during the process of fermentation and germination.

[13] See History of the Jews, p. 71.

[14] It is said by Whewell, that the murrain is supposed to have fallen
only on the animals which were in the open pasture.--_History of the Jews._

"J. S. Michael Leger, published at Vienna, in 1775, a treatise concerning
the mildew as the principal cause of the epidemic disease among cattle. The
mildew is that which _burns_ and _dries_ the grass and leaves. It is
observed early in the morning, particularly after _thunder-storms_. Its
poisonous quality, which does not last above twenty-four hours, never
operates but when it is swallowed immediately after its
falling."--_Mitchell on Fevers._

[15] "The prevalence of the south-east wind was observed to be particularly
favourable to the increase of both cholera and influenza: and I cannot but
think that this had some connexion with the general tendency exhibited by
the former to spread from east to west. Has the morbific property of this
wind aught to do with the haziness of the air when it prevails--a haziness
seen in the country remote from smoke, and quite distinct from fog? What is
this haze? In the west of England a hazy day in spring is called a
_blight_."--_Dr. Williams' Principles of Medicine._

[16] We are to understand also that some peculiar operation took place of a
nature difficult to comprehend, which seems also to typify reproduction,
for the handfuls of ashes which Moses threw into the air _became a dust in
all the land of Egypt_, thus signifying an enormous reproduction of atomic
matter.

[17] The Chinese affect to trace the origin of Small Pox back to a period
of at least 3000 years, or 20 years beyond the era of the Trojan war, 1212,
A. C.

The Chinese pretend to discriminate no less than 40 different species of
Small Pox.

"They also pretend to discover whether a person has died by violence or
from natural causes, not only after the body has been some time interred
and decomposition of the softer parts has commenced, but even after the
total disappearance of the soft parts, and when the dry skeleton alone is
left."--For the process, see _Hamilton's History of Medicine_, vol. i. p.
31.

To give some notion of the state of Medical Science among the Chinese, I
may quote the following: "The theory of the circulation of the blood, Du
Halde affirms, was known by the Chinese about 400 years after the deluge;
be this assertion veracious or not, no correct knowledge up to the present
day, do the nation possess of the circulating system of the human
frame."--_China and the Chinese, Henry Charles Sirr, M. A._

According to their anatomy, the trachea extends from the larynx through the
lungs to the heart, whilst the oesophagus goes over them to the stomach.

[18] "And Aaron took as Moses commanded, and ran into the midst of the
congregation: and behold the plague was begun among the people; and he put
on incense and made an atonement for the people. And he stood between the
dead and the living, and the plague was stayed."--_Numbers._

The practice of burning scented herbs has been observed in all times during
an invasion of the plague, as a means of protection. Also wearing perfumes
and aromatic preparations has been recommended. Whether they have any
counteracting influence, it is impossible to say.

Virgil in the third Georgic speaks of a murrain among cattle. He says, if
any wore a vestment made of wool from an infected sheep, fiery blains and
filthy sweat overspread his body, and ere long a pestilential fire preyed
upon his infected limbs.

In his directions for preserving the health of flocks he says--

 "Disce et odoratam stabulis accendere cedrum."

The motive for burning the fragrant cedar is not mentioned; we cannot doubt
but it was a good one, and having some great practical utility, from the
following line--

 "Galbaneoque agitare graves nidore chelydros."

[19] The earliest mention of this complaint upon which reliance can be
placed, is an ancient Arabic MS. preserved in the public library at Leyden.
"This year, in fine, the Small Pox and Measles made their first appearance
in Arabia." The year alluded to being that of the birth of Mahomet, or the
year 572 of the Christian æra.--_Hamilton's History of Medicine_, vol. i.
p. 215.

[20] Dr. W. A. Greenhill's translation.

[21] The Black Assize at Oxford, 1572, is an instance in which a
pestilential vapour suddenly appeared in the court, "whereby the judge,
several noblemen, and more than 300 others, died within three days."

"Of an unaccountable vapour suddenly coming, I have this relation from
Richard Humphrey, my neighbour, and a man of veracity, that on Wednesday,
April 27, 1727, as he and one Walter, were travelling a-foot from
Canterbury; when they came to Rainham, they were assaulted with such a
strong loathsome stink, as he thought was like the stench from a corrupted
human corpse. They were so offended at it, as thinking it was from carrion
in that town, that they would not stay there to rest and refresh
themselves, but travelled on for about two hours, mostly in the stench, but
sometimes out of it, till they came to the hill that leads down to Chatham:
and there they went clear out of it and smelt it no more."--_Dr. Fuller_.

It appears that these persons did not fall sick of any disease, but the
fact of itself is remarkable enough.

[22] Hamilton's History of Medicine.

[23] It has been said, that "an induction once carefully drawn, is as
perfect from a single instance as it is from ten thousand, and that it is
only an uncultivated mind which requires a load and accumulation of
knowledge to assist his thoughts."--_Sewell_ "on the Cultivation of the
Intellect."

[24] See Dr. Alison's Pamphlet on the Fever in Edinburgh.

[25] Earthquakes have in all times been considered to have some connexion
with pestilences. "A most grievous pestilence broke out in Seleucia, which
from thence to Parthia, Greece, and Italy, spread itself through a great
part of the world, from the opening of an ancient vault in the temple of
Apollo, and that it raged with so much fury as to sweep away a third part
of the inhabitants of those countries it visited."--_Dr. Quincy, on the
Causes of Pestilential Disease._

"Upon an earthquake the earth sends forth noisome vapours which infect the
air; so it was observed to be at Hull in Yorkshire, by the Rev. Mr. Banks,
of that place, after a small earthquake there in 1703, it was a most sickly
time for a considerable while afterwards, and the greatest mortality that
had been known for fifteen years."--_Anonymous_, 1769.

[26] See Sharon Turner's Sacred History, text and notes, vol. i. p. 161 &
162.

[27]

 "Each seed includes a plant; that plant, again,
  Has other seeds, which other plants contain,
  Those other plants have all their seeds; and those
  More plants, again, successively enclose.
  Thus ev'ry single berry that we find,
  Has really in itself whole forests of its kind.
  Empire and wealth one acorn may dispense,
  By fleets to sail a thousand ages hence;
  Each myrtle-seed includes a thousand groves,
  Where future bards may warble forth their loves."

[28] "On June 5th, 1849, a man and his son, a lad aged 14 years, left Noss
to fish, and when five miles out at sea, no vessel being in sight, they
both simultaneously became aware of a hot _offensive_ stream of air passing
over them. It was so decided, that the crab pots were examined to discover
if it were from them, but it did not, and five minutes after the father's
attention was directed to the boy, who was vomiting and purging."--_Dr. Roe
on the Cholera at Plymouth, Med. Gaz. Aug. 24th, 1850._

[29] Linnæus remarked that Erigeron Canadense was introduced into gardens
near Paris from North America. The seeds had been carried by the wind, and
this plant was in the course of a century spread over all France, Italy,
Sicily and Belgium.

[30] Hecker.

[31] This is found most generally to be the case where rivers flow through
uncultivated tracts of country. The Californian emigrants suffer much from
diarrhoea and dysentery, if they drink of the river and certain well waters
of that gold district.

[32] "Purification from leprosy. As this fearful disease was contagious and
hereditary to the third and fourth generation, the separation of lepers
from the camp and congregation, and the destruction of infected houses and
clothes, was of the utmost importance to the preservation of public health.

"Leprosy was of three kinds: 1st, Leprosy in man. 2nd, Leprosy in houses.
3rd, Leprosy in clothes.

"Contagious or malignant leprosy was of two kinds, viz.

"1st. The white leprosy, or bright berat, which was the most serious and
obstinate form which leprosy assumes. It exhibited itself as a bright white
and spreading scale, on an elevated base; turning the hair white in
patches, which were continually spreading.

"2nd. The black leprosy, or dusky berat, which was less serious than the
foregoing. It did not change the colour of the hair, nor was there any
depression in the dusky spot; but the patches were perpetually spreading,
as in the white leprosy."--_Analysis and Summary of Old Testament History._
_Oxford._

[33] The Mexican Aloe blows when nine years old, and then dies. At least
this is its usual course in the island of Cuba.

[34] "Ground that has not been disturbed for some hundred years, on being
ploughed, has frequently surprised the cultivator by the appearance of
plants which he never sowed, and often which were then unknown to the
country. The principle has been ascertained to be capable of existing in
this latent state for above 2000 years, unextinguished, and springing again
into active vegetation, as soon as planted in a congenial soil.

"In boring for water near Kingston on Thames, some earth was brought up
from a depth of 360 feet, and though carefully covered with a hand-glass to
prevent the possibility of other seeds being deposited on it, was yet in a
short time covered with vegetation.

"Turner says, from the depth, these seeds must have been of the diluvian
age."--_Jesse's Gleanings._

[35] Hamilton's History of Medicine, vol. ii. p. 276, note.

[36] "What I wish you to remark is this, that while almost all men are
prone to take the disorder, large portions of the world have remained for
centuries entirely exempt from it, until at length it was imported, and
that then it infallibly diffused and established itself in those
parts."--_Dr. Watson on the Principles and Practice of Physic._

Dr. R. Williams says, "The seeds of intermittent fever lay dormant for
months, it was not at all uncommon for cases of intermittent fever to be
brought into the hospital eight or ten months after the patients had
subjected themselves to the influence of paludal or marsh effluvia."

[37] I have observed in the hot-houses, that many of the exotic plants,
which are in company with the diseased vines, have been attacked, while
others again have been entirely free.

[38] By causes of the greatest variety plants may become extinct for a
time. It is not very easy to trace them, but one fact may be mentioned in
proof of the statement. Dr. Prichard states that vast forests are destroyed
either for the purpose of tillage or accidentally by conflagrations. "The
same trees do not reappear in the same spots, but they have successors,
which seem regularly to take their place. Thus the pine forests of North
America when burnt, afford room to forests of oak trees."

[39] Hecker says of Chalin de Vinario, that "he asserted boldly and with
truth, that _all epidemic diseases might become contagious, and all fevers
epidemic_,--which attentive observers of all subsequent ages have
confirmed." P. 60.

[40] In 1539, the thirty-first year of Henry the Eighth, was great death of
burning agues and flixes; and such a drought that welles and small rivers
were dryed up, and many cattle dyed for lacke of water; the salt water
flowed above London Bridge.--_Stowe._

In 1556, the fourth of Mary, and the third of Philip, about this time began
the burning fevers, quarterne agues, and other strange diseases, whereof
died many.--_Stowe._

The next winter, 1557, the quarterne agues continued in like manner, or
more vehemently than they had done the last yere.--_Stowe._

[41] Every writer on the climate of Egypt has remarked, that the Endemic
Fever which is so frequent, originating on the coast, particularly about
Alexandria, becomes occasionally so virulent, that it cannot be
distinguished from the _true Plague._--_Robertson on the Atmosphere_, vol.
2. p. 384.

"Endemial Fevers of every situation become occasionally so aggravated, that
they cannot be distinguished from such as originate from contagion; and in
every unusual virulence of this Endemic Fever, it is probable that it may
be propagated afterwards by contagion as every epidemic." _Ibid._ p. 388.

[42] Dr. Ure.

[43] "The metamorphosis of starch into sugar depends simply, as is proved
by analysis, on the addition of the elements of water. All the carbon of
the starch is found in the sugar; none of its elements have been separated,
and except the elements of water, no foreign element has been added to it
in this transformation."--_Liebig_, _Organic Chemistry_, p. 71.

[44] As regards starch there appears to be some peculiar faculty regarding
it. It is converted into sugar during the ripening of fruit, and it is just
possible that being as it is of a cellular nature, the property of vitality
may attach to it until it has, by being converted into sugar, fulfilled its
destination.

[45] Though I do not consider that the fermentation process is a fac-simile
of diseased action, yet I think its phenomena generally afford an apt
illustration of the changes which may be effected by living germs. Many
able chemists still maintain the entire dependence of fermentation upon the
Torula: "M. Blondeau propounds the view that _every kind_ of fermentation
is _caused_ by the development of fungi."

The varieties of opinions found in the literature of this subject, forms a
curious specimen of scientific enquiry, and is sufficient alone to convince
us of its vast importance and extensive relations.

[46] By Dr. Mantell.

[47] Mitchell on Fevers.

[48] We wonder, and ask ourselves: "What does SMALL mean in
Nature?"--_Schleiden's Lectures on Botany._

[49] Speaking of the bunt in wheat: "It appears certainly to be contagious,
from numerous experiments, which shew that the contagious principle lasts a
long time. I have tried it myself; some, however, doubt it, but it cannot
be denied, that seed sown, infected with bunt, produces plants similarly
affected; every one who has had the slightest experience must be convinced
of it."--_Essay on the Diseases of Plants._ _Count Ré._

[50] We have already spoken of the effects of these poisons, and have
stated that the amount of each poison capable of destroying the body is
pretty accurately known.

[51] The italics are my own.

[52] Gmelin says: "But the mode of action in these transformations,
sometimes admits of other explanations; and when this is not the case, our
conception of it is by no means sufficiently clear to justify the positive
assumption of this, so called contact-action or catalytic force, which,
after all, merely states the fact without explaining it"--_Gmelin's
Hand-book of Chemistry_, vol. i. p. 115.

[53] The history and symptoms of some epidemic diseases, such as cholera
and influenza, are not inconsistent with the hypothesis that they are
caused by the sudden development of animalcules from ova in the blood. But
there is a total want of direct observation in support of this
hypothesis.--_Dr. Williams' Principles of Medicine._

[54] Since writing the above, I have referred for information on this
subject, and find, that the Anguillula aceti exhibits sexual distinctions;
and that the ovaries of the females are situated on each side of the
alimentary canal.--_Cyclo. Anat. and Phys. Art. Entozoa._

[55] Speaking of the examination of the infusory animalcules--Mr. Kirby
says: "But to us the wondrous spectacle is seen, and known only in part;
for those that still escape all our methods of assisting sight, and remain
members of the invisible world, may probably _far exceed those that we
know_."--_Bridgewater Treatise_, vol. i. p. 158.

[56] Mr. Owen has added another class, as the first, called Protelmintha,
which comprises the cercariadæ and vibrionidæ.

[57] "It is probable that in the waters of our globe an infinity of animal
and vegetable molecules are suspended, that are too minute to form the food
of even the lowest and minute animals of the visible creation: and
therefore an infinite host of invisibles was necessary to remove them as
nuisances."--_Bridgewater Treatise_, vol. i. p. 159.

"When Creative Wisdom covered the earth with plants, and peopled it with
animals, He laid the foundations of the vegetable and animal kingdoms with
such as were most easily convertible into nutriment for the tribes
immediately above them. The first plants, and the first animals, are
scarcely more than animated molecules,* and appear analogues of each other;
and those above them in each kingdom represent jointed
fibrils."+--_Bridgewater Treatise_, vol. i. p. 162.

* Globulina and Monus. + Oscillatoria and Vibrio.

[58] "A treatise which should present a systematic arrangement of all the
diseases of plants, giving in detail the exact history of each, and adding
the means of preventing and curing them, would certainly be of the greatest
utility to agriculture." --_Essay on the Diseases of Plants, Count Philippo
Ré, translated into Gardener's Chron._

[59] "Plenck published a treatise on Vegetable Pathology, in which he
divided diseases into eight classes: 1. External injuries; 2. Flux of
juices; 3. Debility; 4. Cachexies; 5. Putrefactions; 6. Excrescences; 7.
Monstrosities; and 8. Sterility. And he concludes with an enumeration of
the animals which injure plants."--_Essay on the Diseases of Plants,
Gardener's Chronicle._

[60] The Bunt. "This disease appears at the moment of the germination of
the plant. The affected individuals are of a dark green, and the stem is
discoloured. As the ears are issuing from the sheaths, their stalks are of
a dark green, but very slender. When the ear has fully grown out, its dull,
dirty colour, causes it to be immediately distinguished from the healthy
ones, and it soon turns white."--_Essay on the Diseases of Plants._

[61] _Vidi_ understood.

[62] "At the close of the year 1665," says Dr. Hodges, "even women, before
deemed barren, were said to prove prolific."

"After the cessation of the Black Plague, a greater fecundity in women was
every where remarkable--a grand phenomenon, which from its occurrence after
every destructive pestilence proves to conviction, if any occurrence can do
so, the prevalence of a higher power in the direction of general organic
life. Marriages were almost without exception prolific; and double and
treble births were more frequent than at other times."--_Hecker_, p. 31.

[63] It is stated that on the decline of the Plague, 1665, those who
returned early to London, or new comers, were certain to be attacked. In
proof of this the 1st week of November, the deaths increased 400, and
"physicians reported that above 3000 fell sick that week, mostly new
comers."

See also Dr. Copland's Dict. Pract. Med. Epidemic and Endemic Diseases.

"The hardy mountaineer is a surer victim of paludal fever, whether he
visits the low countries of the tropics, or the marshes of a more temperate
climate, than the feebler native of those countries."--_Dr. R. Williams on
Morbid Poisons._

[64] "Substances presented to the gastro-intestinal surfaces, are mixed up
with various secretions, mucus, saliva, gastric juice, bile, pancreatic
liquor, and special exudations from the peculiar glands of each successive
section, while aerial poisons, unmixed and unfettered, are applied at once
to a surface on which, behind scarcely a shadow of a film, circulates the
blood prepared, by the habitual action of the respiratory function, to
absorb almost every vapour, and every odour, which may not be too
irritating to pass the gates of the _glottis_."--_Mitchell on Fevers._

[65] Hecker on the "Black Death."

[66] The stomach in some cases is no doubt the medium by which some
diseases are contracted. It is well known, that in many places the water
induces diarrhoea, the permanent residents, however, may not suffer, but
all new comers are more or less affected by drinking it.

[67] "Similar effects have been experienced from the use of mouldy
provisions."--_Dr. Lindley's Vegetable Kingdom._

[68] "Untold numbers die of the diseases produced by scanty and
_unwholesome food_."--_Southey._

A large, nay, a most extensive adulteration of flour with plaster of Paris
was detected not many years since. The flour was supplied by a contractor
for the manufacture of biscuits for the navy.

[69] See Southey's Doctor, vol. ii. interchapter vi. p. 115, for an
illustration of this subject.

[70] Both these patients died.

[71] "A good part of the clove trees which grew so plentifully in the
island of Ternate, being felled at the solicitation of the Dutch, in order
to heighten the price of that fruit, such a change ensued in the air, _as
shewed the salutary effect of the effluvia of clove trees and their
blossoms; the whole island, soon after they were cut down, becoming
exceeding sickly_."

[72] The observation is originally taken from the City Remembrancer, 133.

[73] See Hamilton's History of Medicine, vol. i. p. 4.

[74] Feuchtersleben's Medical Psychology, p. 176, 177.

[75] Ibid. p. 321.

       *       *       *       *       *


CHANGES MADE AGAINST PRINTED ORIGINAL.

Page 136. "the idea of Protophyta, or first plants": 'Prolophyta' in
original.

Page 140. "an extensive bearing of each individual part": 'indivdual' in
original.





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