SUMMARY OF THE 'PHILOSOPHIE ZOOLOGIQUE.'
The first part of the '_Philosophie Zoologique_' is the one which deals
with the doctrine of evolution or descent with modification. It is to
this, therefore, that our attention will be confined. Yet only a
comparatively small part of the three hundred and fifty pages which
constitute Lamarck's first part are devoted to setting forth the reasons
which led him to arrive at his conclusions--the greater part of the
volume being occupied with the classification of animals, which we may
again omit, as foreign to our purpose.
I shall condense whenever I can, but I do not think the reader will find
that I have left out much that bears upon the argument. I shall also use
inverted commas while translating with such freedom as to omit several
lines together, where I can do so without suppressing anything essential
to the elucidation of Lamarck's meaning. I shall, however, throughout
refer the reader to the page of the original work from which I am
translating.
"The common origin of bodily and mental phenomena," says Lamarck in his
preliminary chapter, "has been obscured, because we have studied them
chiefly in man, who, as the most highly developed of living beings,
presents the problem in its most difficult and complicated aspect. If we
had begun our study with that of the lowest organisms, and had proceeded
from these to the more complex ones, we should have seen the progression
which is observable in organization, and the successive acquisition of
various special organs, with new faculties for every additional organ.
We should thus have seen that sense of needs--originally hardly
perceptible, but gradually increasing in intensity and variety--has led
to the attempt to gratify them; that the actions thus induced, having
become habitual and energetic, have occasioned the development of organs
adapted for their performance; that the force which excites organic
movements can in the case of the lowest animals exist outside them and
yet animate them; that this force was subsequently introduced into the
animals themselves, and fixed within them; and, lastly, that it gave
rise to sensibility and, in the end, to intelligence."[208] The reader
had better be on his guard here, and whenever Lamarck is speculating
about the lowest forms of action and sensation. I have thought it well,
however, to give enough of these speculations, as occasion arises, to
show their tendency.
"Sensation is not the proximate cause of organic movements. It may be so
with the higher animals, but it cannot be shown to be so with plants,
nor even with all known animals. At the outset of life there was none of
that sensation which could only arise where organic beings had already
attained a considerable development. Nature has done all by slow
gradations, both organs and faculties being the outcome of a progressive
development.[209]
"The mere composition of an animal is but a small part of what deserves
study in connection with the animal itself. The effects of its
surroundings in causing new wants, the effects of its wants in giving
rise to actions, those of its actions in developing habits and
tendencies, the effects of use and disuse as affecting any organ, the
means which nature takes to preserve and make perfect what has been
already acquired--these are all matters of the highest importance.[210]
"In their bearing upon these questions the invertebrate animals are more
important and interesting than the vertebrate, for they are more in
number, and being more in number are more varied; their variations are
more marked, and the steps by which they have advanced in complexity are
more easily observed.[211]
"I propose, therefore, to divide this work into three parts, of which
the first shall deal with the conventions necessary for the treatment of
the subject, the importance of analogical structures, and the meaning
which should be attached to the word species. I will point out on the
one hand the evidence of a graduated descending scale, as existing
between the highest and the lowest organisms; and, on the other, the
effect of surroundings and habits on the organs of living beings, as the
cause of their development or arrest of development. Lastly, I will
treat of the natural order of animals, and show what should be their
fittest classification and arrangement."[212]
It seems unnecessary to give Lamarck's intentions with regard to his
second and third parts, as they do not here concern us; they deal with
the origin of life and mind.
The first chapter of the work opens with the importance of bearing in
mind the difference between the conventional and the natural, that is to
say, between words and things. Here, as indeed largely throughout this
part of his work, he follows Buffon, by whom he is evidently influenced.
"The conventional deals with systems of arrangement, classification,
orders, families, genera, and the nomenclature, whether of different
sections or of individual objects.
"An arrangement should be called systematic, or arbitrary, when it does
not conform to the genealogical order taken by nature in the development
of the things arranged, and when, by consequence it is not founded upon
well-considered analogies. There is such a thing as a natural order in
every department of nature; it is the order in which its several
component items have been successively developed.[213]
"Some lines certainly seem to have been drawn by Nature herself. It was
hard to believe that mammals, for example, and birds, were not
well-defined classes. Nevertheless the sharpness of definition was an
illusion, and due only to our limited knowledge. The ornithorhynchus and
the echidna bridge the gulf.[214]
"Simplicity is the main end of any classification. If all the races, or
as they are called, species, of any kingdom were perfectly known, and if
the true analogies between each species, and between the groups which
species form, were also known, so that their approximations to each
other and the position of the several groups were in conformity with the
natural analogies between them--then classes, orders, sections, and
genera would be families, larger or smaller; for each division would be
a greater or smaller section of a natural order or sequence.[215] But in
this case it would be very difficult to assign the limits of each
division; they would be continually subjected to arbitrary alteration,
and agreement would only exist where plain and palpable gaps were
manifest in our series. Happily, however, for classifiers there are, and
will always probably remain, a number of unknown forms."[216]
That the foregoing is still felt to be true by those who accept
evolution, may be seen from the following passage, taken from Mr.
Darwin's 'Origin of Species':--
"As all the organic beings which have ever lived can be arranged within
a few great classes; and as all within each class have, according to our
theory, been connected together by fine gradations, the best, and if our
collections were nearly perfect, the only possible arrangement would be
genealogical: descent being the hidden bond of connection which
naturalists have been seeking under the term of the Natural System. On
this view, we can understand how it is that in the eyes of most
naturalists, the structure of the embryo is even more important for
classifications than that of the adult."[217]
In his second chapter Lamarck deals with the importance of comparative
anatomy, and the study of homologous structures. These indicate a sort
of blood relationship between the individuals in which they are found,
and are our safest guide to any natural system of classification. Their
importance is not confined to the study of classes, families, or even
species; they must be studied also in the individuals of each species,
as it is thus only, that we can recognize either identity or difference
of species. The results arrived at, however, are only trustworthy over a
limited period, for though the individuals of any species commonly so
resemble one another at any given time, as to enable us to generalize
from them, at the date of our observing them, yet species are not fixed
and immutable through all time: they change, though with such extreme
slowness that we do not observe their doing so, and when we come upon a
species that _has_ changed, we consider it as a new one, and as having
always been such as we now see it.[218]
"It is none the less true that when we compare the same kind of organs
in different individuals, we can quickly and easily tell whether they
are very like each other or not, and hence, whether the animals or
plants in which they are found, should be set down as members of the
same or of a different species. It is only therefore the general
inference drawn from the apparent immutability of species, that has
been too inconsiderately drawn.[219]
"The analogies and points of agreement between living organisms, are
always incomplete when based upon the consideration of any single organ
only. But though still incomplete, they will be much more important
according as the organ on which they are founded is an essential one or
otherwise.
"With animals, those analogies are most important which exist between
organs most necessary for the conservation of their life. With plants,
between their organs of generation. Hence, with animals, it will be the
interior structure which will determine the most important analogies:
with plants it will be the manner in which they fructify.[220]
"With animals we should look to nerves, organs of respiration, and those
of the circulation; with plants, to the embryo and its accessories, the
sexual organs of their flowers, &c.[221] To do this, will set us on to
the Natural Method, which is as it were a sketch traced by man of the
order taken by Nature in her productions.[222] Nevertheless the
divisions which we shall be obliged to establish, will still be
arbitrary and artificial, though presenting to our view sections
arranged in the order which Nature has pursued.[223]
"What, then," he asks,[224] "_is_ species--and can we show that species
has changed--however slowly?" He now covers some of the ground since
enlarged upon in Mr. Darwin's second chapter, in which the arbitrary
nature of the distinction between species and varieties is so well
exposed. "I shall show," says Lamarck (in substance, but I am compelled
to condense much), "that the habits by which we now recognize any
species, are due to the conditions of life [_circonstances_] under which
it has for a long time existed, and that these habits have had such an
influence upon the structure of each individual of the species, as to
have at length modified this structure, and adapted it to the habits
which have been contracted.[225]
"The individuals of any species," he continues, "certainly resemble
their parents; it is a universal law of nature that all offspring should
differ but little from its immediate progenitors, but this does not
justify the ordinary belief that species never vary. Indeed, naturalists
themselves are in continual difficulty as regards distinguishing species
from varieties; they do not recognize the fact that species are only
constant as long as the conditions in which they are placed are
constant. Individuals vary and form breeds which blend so insensibly
into the neighbouring species, that the distinctions made by naturalists
between species and varieties, are for the most part arbitrary, and the
confusion upon this head is becoming day by day more serious.[226]
"Not perceiving that species will not vary as long as the conditions in
which they are placed remain essentially unchanged, naturalists have
supposed that each species was due to a special act of creation on the
part of the Supreme Author of all things. Assuredly, nothing can exist
but by the will of this Supreme Author, but can we venture to assign
rules to him in the execution of his will? May not his infinite power
have chosen to create an order of things which should evolve in
succession all that we know as well as all that we do not know? Whether
we regard species as created or evolved, the boundlessness of his power
remains unchanged, and incapable of any diminution whatsoever. Let us
then confine ourselves simply to observing the facts around us, and if
we find any clue to the path taken by Nature, let us say fearlessly that
it has pleased her Almighty Author that she should take this path.[227]
"What applies to species applies also to genera; the further our
knowledge extends, the more difficult do we find it to assign its exact
limits to any genus. Gaps in our collections are being continually
filled up, to the effacement of our dividing lines of demarcation. We
are thus compelled to settle the limits of species and variety
arbitrarily, and in a manner about which there will be constant
disagreement. Naturalists are daily classifying new species which blend
into one another so insensibly that there can hardly be found words to
express the minute differences between them. The gaps that exist are
simply due to our not having yet found the connecting species.
"I do not, however, mean to say that animal life forms a simple and
continuously blended series. Life is rather comparable to a
ramification. In life we should see, as it were, a ramified continuity,
if certain species had not been lost. The species which, according to
this illustration, stands at the extremity of each bough, should bear a
resemblance, at least upon one side, to the other neighbouring species;
and this certainly is what we observe in nature.
"Having arranged living forms in such an order as this, let us take one,
and then, passing over several boughs, let us take another at some
distance from it; a wide difference will now be seen between the species
which the forms selected represent. Our earliest collections supplied us
with such distantly allied forms only; now, however, that we have such
an infinitely greater number of specimens, we can see that many of them
blend one into the other without presenting noteworthy differences at
any step."[228]
This has been well extended by Mr. Darwin in a passage which
begins:--"The affinities of all beings of the same class have sometimes
been represented by a great tree. I believe that this simile largely
speaks the truth."[229]
"What, then," continues Lamarck, "can be the cause of all this? Surely
the following: namely, that when individuals of any species change their
situation, climate, mode of existence, or habits [conditions of life],
their structure, form, organization, and in fact their whole being
becomes little by little modified, till in the course of time it
responds to the changes experienced by the creature."[230]
In his preface Lamarck had already declared that "the thread which gives
us a clue to the causes of the various phenomena of animal
organization, in the manifold diversity of its developments, is to be
found in the fact that Nature conserves in offspring all that their life
and environments has developed in parents." Heredity--"the hidden bond
of common descent"--tempered with the modifications induced by changed
habits--which changed habits are due to new conditions and
surroundings--this with Lamarck, as with Buffon and Dr. Darwin, is the
explanation of the diversity of forms which we observe in nature. He now
goes on to support this--briefly, in accordance with his design--but
with sufficient detail to prevent all possibility of mistake about his
meaning.
"In the same climate differences in situation, and a greater or less
degree of exposure, affect simply, in the first instance, the
individuals exposed to them; but in the course of time, these repeated
differences of surroundings in individuals which reproduce themselves
continually under similar circumstances, induce differences which become
part of their very nature; so that after many successive generations,
these individuals, which were originally, we will say, of any given
species, become transformed into a different one."[231]
"Let us suppose that a grass growing in a low-lying meadow gets carried
by some accident to the brow of a neighbouring hill, where the soil is
still damp enough for the plant to be able to exist. Let it live here
for many generations, till it has become thoroughly accustomed to its
position, and let it then gradually find its way to the dry and almost
arid soil of a mountain side; if the plant is able to stand the change
and to perpetuate itself for many generations, it will have become so
changed that botanists will class it as a new species."[232]
"The same sort of process goes on in the animal kingdom, but animals are
modified more slowly than plants."[233]
The sterility of hybrids, to which Mr. Darwin devotes a great part of
the ninth chapter of his 'Origin of Species,'[234] is then touched
on--briefly, but sufficiently--as follows:--
"The idea that species were fixed and immutable involved the belief that
distinct species could not be fertile _inter se_. But unfortunately
observation has proved, and daily proves, that this supposition is
unfounded. Hybrids are very common among plants, and quite sufficiently
so among animals to show that the boundaries of these so-called
immutable species are not so well defined as has been supposed. Often,
indeed, there is no offspring between the individuals of what are called
distinct species, especially when they are widely different, and again,
the offspring when produced is generally sterile; but when there is less
difference between the parents, both the difficulty of breeding the
hybrid, and its sterility when produced, are found to disappear. In this
very power of crossing we see a source from which breeds, and ultimately
species, may arise."[235]
Mr. Darwin arrives at the same conclusion. He writes:--
"We must, therefore, either give up the belief of the universal
sterility of species when crossed, or we must look at this sterility in
animals, not as an indelible characteristic, but as one capable of being
removed by domestication.
"Finally, on considering all the ascertained facts on the intercrossing
of plants and animals, it may be concluded that some degree of
sterility, both in first crosses and in hybrids, is an exceedingly
general result, but that it cannot, under our present state of
knowledge, be considered as absolutely universal."[236]
Returning to Lamarck, we find him saying:--
"The limits, therefore, of so-called species are not so constant and
unvarying as is commonly supposed. Consider also the following. All
living forms upon the face of the globe have been brought forth in the
course of infinite time by the process of generation only. Nature has
directly created none but the lowest organisms; these she is still
producing every day, they being, as it were, the first sketches of life,
and produced by what is called spontaneous generation. Organs have been
gradually developed in these low forms, and these organs have in the
course of time increased in diversity and complexity. The power of
growth in each living body has given rise to various modes of
reproduction, and thus progress, already acquired, has been preserved
and handed down to offspring.[237] With sufficient time, favourable
conditions of life [_circonstances_], successive changes in the surface
of the globe, and the power of new surroundings and habits to modify the
organs of living bodies, all animal and vegetable forms have been
imperceptibly rendered such as we now see them. It follows that species
will be constant only in relation to their environments, and cannot be
as old as Nature herself.
"But what are we to say of instinct? Can we suppose that all the tricks,
cunning, artifices, precautions, patience, and skill of animals are due
to evolution only? Must we not see here the design of an all-powerful
Creator? No one certainly will assign limits to the Creator's power, but
it is a bold thing to say that he did not choose to work in this way or
that way, when his own handiwork declares to us that this is the way he
chose. I find proof in Nature--meaning by nature the _ensemble_ of all
that is,[238] but regarding her as herself the effect of an unknown
first cause[239]--that she is the author of organization, life, and even
sensation; that she has multiplied and diversified the organs and mental
powers of the creatures which she sustains and reproduces; that she has
developed in animals, through the sole instrumentality of sense of need
as establishing and directing their habits, all actions and all habits,
from the simplest up to those which constitute instinct, industry, and
finally reason.[240]
"Against this it is alleged that we have no reason to believe species to
have changed within any known era. The skeletons of some Egyptian birds,
preserved two or three thousand years ago, differ in no particular from
the same kind of creatures at the present day. But this is what we
should expect, inasmuch as the position and climate of Egypt itself do
not appear to have changed. If the conditions of life have not varied,
why should the species subjected to those conditions have done so?
Moreover, birds can move about freely, and if one place does not suit
them they can find another that does. All that these Egyptian mummies
really prove is, that there were animals in Egypt two or three thousand
years ago which are like the animals of to-day; but how short a space is
two or three thousand years, as compared with the time which Nature has
had at her disposal! A time infinitely great _qua_ man, is still
infinitely short _qua_ Nature.[241]
"If, however, we turn to animals under confinement, we find immediate
proof that the most startling changes are capable of being produced
after some generations of changed habits. In the sixth chapter we shall
have occasion to observe the power of changed conditions
[_circonstances_] to develop new desires in animals, and to induce new
courses of action; we shall see the power which these new actions will
have, after a certain amount of repetition, to engender new habits and
tendencies; and we shall also note the effects of use and disuse in
either fortifying and developing an organ, or in diminishing it and
causing it to disappear. With plants under domestication, we shall find
corresponding phenomena. Species will thus appear to be unchangeable for
comparatively short periods only."[242]
It is interesting to see that Mr. Darwin lays no less stress on the
study of animals and plants under domestication than Buffon, Dr. Darwin,
and Lamarck. Indeed, all four writers appear to have been in great
measure led to their conclusions by this very study. "At the
commencement of my investigations," writes Mr. Darwin, "it seemed to me
probable that a careful study of domesticated animals and of cultivated
plants would offer the best chance of making out this obscure problem.
Nor have I been disappointed; in this and in all other perplexing cases,
I have invariably found that our knowledge, imperfect though it be, of
variation under domestication, afforded the best and safest clue. I may
venture to express my conviction of the high value of such studies,
though they have been very commonly neglected by naturalists."[243]
In justice to the three writers whom I have named, it should be borne in
mind that they also ventured to express their conviction of the high
value of these studies. Buffon, indeed, as we have seen, gives animals
under domestication the foremost place in his work. He does not treat of
wild animals till he has said all he has to say upon our most important
domesticated breeds,--on whose descent from one or two wild stocks he is
never weary of insisting. It was doubtless because of the opportunities
they afforded him for demonstrating the plasticity of living organism
that the most important position in his work was assigned to them.
Lamarck professes himself unable to make up his mind about extinct
species; how far, that is to say, whole breeds must be considered as
having died out, or how far the difference between so many now living
and fossil forms is due to the fact that our living species are
modified descendants of the fossil ones. Such large parts of the globe
were still practically unknown in Lamarck's time, and the recent
discovery of the ornithorhynchus has raised such hopes as to what might
yet be found in Australia, that he was inclined to think that only such
creatures as man found hurtful to him, as, for example, the megatherium
and the mastodon, had become truly extinct, nor was he, it would seem,
without a hope that these would yet one day be discovered. The climatic
and geological changes that have occurred in past ages, would, he
believed, account for all the difference which we observe between living
and fossil forms, inasmuch as they would have changed the conditions
under which animals lived, and therefore their habits and organs would
have become correspondingly modified. He therefore rather wondered to
find so much, than so little, resemblance between existing and fossil
forms.
Buffon took a juster view of this matter; it will be remembered that he
concluded his remarks upon the mammoth by saying that many species had
doubtless disappeared without leaving any living descendants, while
others had left descendants which had become modified.
Lamarck anticipated Lyell in supposing geological changes to have been
due almost entirely to the continued operation of the causes which we
observe daily at work in nature: thus he writes:--
"Every observer knows that the surface of the earth has changed; every
valley has been exalted, the crooked has been made straight, and the
rough places plain; not even is climate itself stable. Hence changed
conditions; and these involve changed needs and habits of life; if such
changes can give rise to modifications or developments, it is clear that
every living body must vary, especially in its outward character, though
the variation can only be perceptible after several generations.
"It is not surprising then that so few living species should be
represented in the geologic record. It is surprising rather that we
should find any living species represented at all.[244]
"Catastrophes have indeed been supposed, and they are an easy way of
getting out of the difficulty; but unfortunately, they are not supported
by evidence. Local catastrophes have undoubtedly occurred, as
earthquakes and volcanic eruptions, of which the effects can be
sufficiently seen; but why suppose any universal catastrophe, when the
ordinary progress of nature suffices to account for the phenomena?
Nature is never _brusque_. She proceeds slowly step by step,
and this with occasional local catastrophes will remove all our
difficulties."[245]
In his fourth chapter Lamarck points out that animals move themselves,
or parts of themselves, not through impulsion or movement communicated
to them as from one billiard ball to another, but by reason of a cause
which excites their irritability, which cause is within some animals and
forms part of them, while it is wholly outside of others.[246]
I should again warn the reader to be on his guard against the opinion
that any animals can be said to live if they have no "inward motion" of
their own which prompts them to act. We cannot call anything alive which
moves only as wind and water may make it move, but without any impulse
from within to execute the smallest action and without any capacity of
feeling. Such a creature does not look sufficiently like the other
things which we call alive; it should be first shown to us, so that we
may make up our minds whether the facts concerning it have been truly
stated, and if so, what it most resembles; we may then classify it
accordingly.
"Some animals change their place by creeping, some by walking, some by
running or leaping; others again fly, while others live in the water and
swim.
"The origin of these different kinds of locomotion is to be found in the
two great wants of animal life: 1, the means of procuring food; 2, the
search after mates with a view to reproduction.
"Since then the power of locomotion was a matter affecting their
individual self-preservation, as well as that of their race, the
existence of the want led to the means of its being gratified."[247]
Lamarck is practically at one with Dr. Erasmus Darwin, that modification
will commonly travel along three main lines which spring from the need
of reproduction, of procuring food, and (Dr. Darwin has added) the power
of self-protection; but Dr. Darwin's treatment of this part of his
subject is more lucid and satisfactory than Lamarck's, inasmuch as he
immediately brings forward instances of various modifications which have
in each case been due to one of the three main desires above specified,
namely, reproduction, subsistence, and self-defence.
Lamarck concludes the chapter with some passages which show that he was
alive--as what Frenchman could fail to be after Buffon had written?--to
the consequences which must follow from the geometrical ratio of
increase, and to the struggle for existence, with consequent survival of
the fittest, which must always be one of the conditions of any wild
animal's existence. The paragraphs, indeed, on this subject are taken
with very little alteration from Buffon's work. As Lamarck's theory is
based upon the fact that it is on the nature of these conditions that
the habits and consequently the structure of any animal will depend, he
must have seen that the shape of many of its organs must vary greatly in
correlation to the conditions to which it was subjected in the matter of
self-protection. I do not see, then, that there is any substantial
difference between the positions taken by Dr. Erasmus Darwin and by
Lamarck in this respect.
"Let us conclude," he writes, "by showing the means employed by nature
to prevent the number of her creatures from injuring the conservation of
what has been produced already, and of the general order which should
subsist.[248]
. . . . . .
"In consequence of the extremely rapid rate of increase of the smaller,
and especially of the most imperfect, animals, their numbers would
become so great as to prove injurious to the conservation of breeds, and
to the progress already made towards more perfect organization, unless
nature had taken precautions to keep them down within certain fixed
limits which she cannot exceed."[249]
This seems to contain, and in a nutshell, as much of the essence of what
Mr. Herbert Spencer and Mr. Charles Darwin have termed the survival of
the fittest in the struggle for existence, as was necessary for
Lamarck's purpose.
To Lamarck, as to Dr. Darwin and Buffon, it was perfectly clear that the
facts, that animals have to find their food under varying circumstances,
and that they must defend themselves in all manner of varying ways
against other creatures which would eat them if they could, were simply
some of the conditions of their existence. In saying that the
surrounding circumstances--which amount to the conditions of
existence--determined the direction in which any plant or animal should
be slowly modified, Lamarck includes as a matter of course the fact that
the "stronger and better armed should eat the weaker," and thus survive
and bear offspring which would inherit the strength and better armour of
its parents. Nothing therefore can be more at variance with the truth
than to represent Lamarck and the other early evolutionists as ignoring
the struggle for existence and the survival of the fittest; these are
inevitably implied whenever they use the word "_circonstances_" or
environment, as I will more fully show later on, and are also expressly
called attention to by the greater number of them.[250]
"Animals, except those which are herbivorous, prey upon one another; and
the herbivorous are exposed to the attacks of the flesh-eating races.
"_The strongest and best armed for attack eat the weaker_, and the
greater kinds eat the smaller. Individuals of the same race rarely eat
one another; they war only with other races than their own."[251]
Dr. Darwin here again has the advantage over Lamarck; for he has pointed
out how the males contend with one another for the possession of the
females, which I do not find Lamarck to have done, though he would at
once have admitted the fact. Lamarck continues:--
"The smaller kinds of animals breed so numerously and so rapidly that
they would people the globe to the exclusion of other forms of life, if
nature had not limited their inconceivable multitude. As, however, they
are the prey of a number of other creatures, live but a short time, and
perish easily with cold, they are kept always within the proportions
necessary for the maintenance both of their own and of other races.[252]
"As regards the larger and stronger animals, they would become dominant,
and be injurious to the conservation of many other races, if they could
multiply in too great numbers. But as it is, they devour one another,
and breed but slowly, and few at a birth, so that equilibrium is duly
preserved among them. Man alone is the unquestionably dominant animal,
but men war among themselves, so that it may be safely said the world
will never be peopled to its utmost capacity."[253]
In his fifth chapter Lamarck returns to the then existing arrangement
and classification of animals.
"Naturalists having remarked that many species, and some genera and even
families present characters which as it were isolate them, it has been
imagined that these approached or drew further from each other according
as their points of agreement or difference seemed greater or less when
set down as it were on a chart or map. They regard the small well-marked
series which have been styled natural families, as groups which should
be placed between the isolated species and their nearest neighbours so
as to form a kind of reticulation. This idea, which some of our modern
naturalists have held to be admirable, is evidently mistaken, and will
be discarded on a profounder and more extended knowledge of
organization, and more especially when the distinction has been duly
drawn between what is due to the action of special conditions and to
general advance of organization."[254]
I take it that Lamarck is here attempting to express what Mr. Charles
Darwin has rendered much more clearly in the following excellent
passage:--
"It should always be borne in mind what sort of intermediate forms must,
on the theory [what theory?], have formerly existed. I have found it
difficult when looking at any two species to avoid picturing to myself
forms _directly_ intermediate between them. But this is a wholly false
view; we should always look for forms intermediate between each species
and a common but unknown progenitor; and the progenitor will generally
have differed in some respects from all its modified descendants. To
give a simple illustration: the fantail and pouter pigeons are both
descended from the rock pigeon. If we possessed all the intermediate
varieties which have ever existed, we should have an extremely close
series, between both and the rock pigeon; but we should have no
varieties directly intermediate between the fantail and the pouter;
none, for instance, combining a tail somewhat expanded with a crop
somewhat enlarged, the characteristic features of these two breeds.
These two breeds, moreover, have become so much modified that, if we had
no historical or indirect evidence regarding their origin, it would not
have been possible to have determined, from a mere comparison of their
structure with that of the rock pigeon C. livia, whether they had
descended from this species, or from some other allied form, as C.
oenas.
"So with natural species, if we look to forms very distinct--for
instance, to the horse and the tapir--we have no reason to suppose that
links directly intermediate between them ever existed, but between each
and an unknown common parent. The common parent will have had in its
whole organization much general resemblance to the tapir and the horse;
but in some points of structure it may have differed considerably from
both, even perhaps more than they differ from each other. Hence in all
such cases we should be unable to recognize the parent form of any two
or more species, even if we closely compared the structure of the parent
with that of its modified descendants, unless at the same time we had a
nearly perfect chain of the intermediate links.
. . . . . .
"By the theory of natural selection [surely this is a slip for "by the
theory of descent with modification"] all living species have been
connected with the parent species of each genus, by differences not
greater than we see between the natural and domestic varieties of the
same species at the present day; and their parent species, now generally
extinct, have in their turn been similarly connected with more ancient
forms, and so on backwards, always converging to the common ancestor of
each great class; so that the number of intermediate and transitional
links between all living and extinct species must have been
inconceivably great. But assuredly if this theory [the theory of descent
with modification or that of "natural selection"?] be true, such have
lived upon the earth."[255]
To return, however, to Lamarck.
"Though Nature," he continues, "in the course of long time has evolved
all animals and plants in a true scale of progression, the steps of this
scale can be perceived only in the principal groups of living forms; it
cannot be perceived in species nor even in genera. The reason of this
lies in the extreme diversity of the surroundings in which each
different race of animals and plants has existed. These surroundings
have often been out of harmony with the growing organization of the
plants and animals themselves; this has led to anomalies, and, as it
were, digressions, which the mere development of organization by itself
could not have occasioned."[256] Or, in other words, to that divergency
of type which is so well insisted on by Mr. Charles Darwin.
"It is only therefore the principal groups of animal and vegetable life
which can be arranged in a vertical line of descent; species and even
genera cannot always be so--for these contain beings whose organization
has been dependent on the possession of such and such a special system
of essential organs.
"Each great and separate group has its own system of essential organs,
and it is these systems which can be seen to descend, within the limits
of the group, from their most complex to their simplest form. But each
organ, considered individually, does not descend by equally regular
gradation; the gradations are less and less regular according as the
organ is of less importance, and is more susceptible of modification by
the conditions which surround it. Organs of small importance, and not
essential to existence, are not always either perfected or degraded at
an equal rate, so that in observing all the species of any class we find
an organ in one species in the highest degree of perfection, while
another organ, which in this same species is impoverished or very
imperfect, is highly developed in another species of the same
group."[257]
The facts maintained in the preceding paragraph are in great measure
supported by Mr. Charles Darwin, who, however, assigns their cause to
natural selection.
Mr. Darwin writes, "Ordinary specific characters are more variable than
generic;" and again, a little lower down, "The points in which all the
species of a genus resemble each other, and in which they differ from
allied genera, are called generic characters; and these characters may
be attributed to inheritance from a common progenitor, for it can rarely
happen that natural selection will have modified several distinct
species fitted to more or less widely different habits, in exactly the
same manner; and as these so called generic characters have been
inherited from before the period when the several species first branched
off from their common progenitor, and subsequently have not varied or
come to differ in any degree, or only in a slight degree, it is not
probable that they should vary at the present day. On the other hand,
the points in which species differ from other species of the same genus
are called specific characters; and as these specific characters have
varied and come to differ since the period when the species branched off
from a common progenitor, it is probable that they should still often be
in some degree variable, or at least more variable than those parts of
the organization which have for a very long time remained
constant."[258]
The fact, then, that it is specific characters which vary most is agreed
upon by both Lamarck and Mr. Darwin. Lamarck, however, maintains that it
is these specific characters which are most capable of being affected by
the habits of the creature, and that it is for this reason they will be
most variable, while Mr. Darwin simply says they _are_ most variable,
and that, this being so, the favourable variations will be preserved and
accumulated--an assertion which Lamarck would certainly not demur to.
"Irregular degrees of perfection," says Lamarck, "and degradation in the
less essential organs, are due to the fact that these are more liable
than the more essential ones to the influence of external circumstances:
these induce corresponding differences in the more outward parts of the
animal, and give rise to such considerable and singular difference in
species, that instead of being able to arrange them in a direct line of
descent, as we can arrange the main groups, these species often form
lateral ramifications round about the main groups to which they belong,
and in their extreme development are truly isolated."[259]
In his summary of the second chapter of his 'Origin of Species,' Mr.
Darwin well confirms this when he says, "In large genera the species are
apt to be closely, but unequally, allied together, forming little
clusters round other species."
"A longer time," says Lamarck, "and a greater influence of surrounding
conditions, is necessary in order to modify interior organs.
Nevertheless we see that Nature does pass from one system to another
without any sudden leap, when circumstances require it, provided the
systems are not too far apart. Her method is to proceed from the more
simple to the more complex.[260]
"She does this not only in the race, but in the individual." Here
Lamarck, like Dr. Erasmus Darwin, shows his perception of the importance
of embryology in throwing light on the affinities of animals--as since
more fully insisted on by the author of the 'Vestiges of Creation,' and
by Mr. Darwin,[261] as well as by other writers. "Breathing through
gills is nearer to breathing through lungs than breathing through
trachea is. Not only do we see Nature pass from gills to lungs in
families which are not too far apart, as may be seen by considering the
case of fishes and reptiles; but she does so during the existence of a
single individual, which may successively make use both of the one and
of the other system. The frog while yet a tadpole breathes through
gills; on becoming a frog it breathes through lungs; but we cannot find
that Nature in any case passes from trachea to lungs."[262]
Lamarck now rapidly reviews previous classifications, and propounds his
own, which stands thus:--I. Vertebrata, consisting of Mammals, Birds,
Fishes, and Reptiles. II. Invertebrata, consisting of Molluscs,
Centipedes, Annelids, Crustacea, Arachnids, Insects, Worms, Radiata,
Polyps, Infusoria.
"The degradation of organism," he concludes, "in this descending scale
is not perfectly even, and cannot be made so by any classification,
nevertheless there is such evidence of sustained degradation in the
principal groups as must point in the direction of some underlying
general principle."[263]
Lamarck's sixth chapter is headed "Degradation and Simplification of the
Animal Chain as we proceed downwards from the most complex to the most
simple Organisms."
"This is a positive fact, and results from the operation of a constant
law of nature; but a disturbing cause, which can be easily recognized,
varies the regular operation of the law from one end to the other of the
chain of life.[264]
"We can see, nevertheless, that special organs become more and more
simple the lower we descend; that they become changed, impoverished, and
attenuated little by little; that they lose their local centres, and
finally become definitely annihilated before we reach the lowest
extremity of the chain.[265]
"As has been said already, the degradation of organism is not always
regular; such and such an organ often fails or changes suddenly, and
sometimes in its changes assumes forms which are not allied with any
others by steps that we can recognize. An organ may disappear and
reappear several times before being entirely lost: but this is what we
might expect, for the cause which has led to the evolution of living
organisms has evolved many varieties, due to external influences.
Nevertheless, looking at organization broadly, we observe a descending
scale."[266]
"If the tendency to progressive development was the only cause which had
influenced the forms and organs of animals, development would have been
regular throughout the animal chain; but it has not been so: Nature is
compelled to submit her productions to an environment which acts upon
them, and variation in environment will induce variation in organism:
this is the true cause of the sometimes strange deviations from the
direct line of progression which we shall have to observe.[267]
"If Nature had only called aquatic beings into existence, and if these
beings had lived always in the same climate, in the same kind of water,
and at the same depth, the organization of these animals would doubtless
have presented an even and regular scale of development. But there has
been fresh water, salt water, running and stagnant water, warm and cold
climates, an infinite variety of depth: animals exposed to these and
other differences in their surroundings have varied in accordance with
them.[268] In like manner those animals which have been gradually fitted
for living in air instead of water have been subjected to an endless
diversity in their surroundings. The following law, then, may be now
propounded, namely:--
"_That anomalies in the development of organism are due to the
influences of the environment and to the habits of the creature._[269]
"Some have said that the anomalies above mentioned are so great
as to disprove the existence of any scale which should indicate
descent; but the nearer we approach species, the smaller we see
differences become, till with species itself we find them at times
almost imperceptible."[270]
Lamarck here devotes about seventy pages to a survey of the animal
kingdom in its entirety, beginning with the mammals and ending with the
infusoria. He points out the manner in which organ after organ
disappears as we descend the scale, till we are left with a form which,
though presenting all the characteristics of life, has yet no special
organ whatever. I am obliged to pass this classification over, but do so
very unwillingly, for it is illustrative of Lamarck, both at his best
and at his worst.
The seventh chapter is headed--
"On the influence of their surroundings on the actions and habits of
animals, and on the effect of these habits and actions in modifying
their organization."
"The effect of different conditions of our organization upon our
character, tendencies, actions, and even our ideas, has been often
remarked, but no attention has yet been paid to that of our actions and
habits upon our organization itself. These actions and habits depend
entirely upon our relations to the surroundings in which we habitually
exist; we shall have occasion, therefore, to see how great is the effect
of environment upon organization.
"But for our having domesticated plants and animals we should never have
arrived at the perception of this truth; for though the influence of the
environment is at all times and everywhere active upon all living
bodies, its effects are so gradual that they can only be perceived over
long periods of time.[271]
"Taking the chain of life in the inverse order of nature--that is to
say, from man downwards--we certainly perceive a sustained but irregular
degradation of organism, with an increasing simplicity both in organism
and faculties.
"This fact should throw light upon the order taken by nature, but it
does not show us why the gradation is so irregular, nor why throughout
its extent we find so many anomalies or digressions which have
apparently no order at all in their manifold varieties.[272] The
explanation of this must be sought for in the infinite diversity of
circumstances under which organisms have been developed. On the one
hand, there is a tendency to a regular progressive development; on the
other, there is a host of widely different surroundings which tend
continually to destroy the regularity of development.
"It is necessary to explain what is meant by such expressions as 'the
effect of its environment upon the form and organization of an animal.'
It must not be supposed that its surroundings directly effect any
modification whatever in the form and organization of an animal.[273]
Great changes in surroundings involve great changes in the wants of
animals, and these changes in their wants involve corresponding changes
in their actions. If these new wants become permanent, or of very long
duration, the animals contract new habits, which last as long as the
wants which gave rise to them.[274] A great change in surroundings, if
it persist for a long time, must plainly, therefore, involve the
contraction of new habits. These new habits in their turn involve a
preference for the employment of such and such an organ over such and
such another organ, and in certain cases the total disuse of an organ
which is no longer wanted. This is perfectly self-evident.[275]
"On the one hand, new wants have rendered a part necessary, which part
has accordingly been created by a succession of efforts: use has kept it
in existence, gradually strengthening and developing it till in the end
it attains a considerable degree of perfection. On the other, new
circumstances having in some cases rendered such or such a part useless,
disuse has led to its gradually ceasing to receive the development which
the other parts attain to; on this it becomes reduced, and in time
disappears.[276]
"Plants have neither actions nor habits properly so called, nevertheless
they change in a changed environment as much as animals do. This is due
to changes in nutrition, absorption and transpiration, to degrees of
heat, light, and moisture, and to the preponderance over others which
certain of the vital functions attain to."
Lamarck is led into the statement that plants have neither actions nor
habits, by his theories about the nervous system and the brain. Plain
matter-of-fact people will prefer the view taken by Buffon, Dr. Darwin,
and, more recently, by Mr. Francis Darwin, that there is no radical
difference between plants and animals.
"The differences between well-nourished and ill-nourished plants become
little by little very noticeable. If individuals, whether animal or
vegetable, are continually ill-fed and exposed to hardships for several
generations, their organization becomes eventually modified, and the
modification is transmitted until a race is formed which is quite
distinct from those descendants of the common parent stock which have
been placed in favourable circumstances.[277] In a dry spring the meagre
and stunted herbage seeds early. When, on the other hand, the spring is
warm but with occasional days of rain, there is an excellent hay-crop.
If, however, any cause perpetuates unfavourable circumstances, plants
will vary correspondingly, first in appearance and general conditions,
and then in several particulars of their actual character, certain
organs having received more development than others, these differences
will in the course of time become hereditary.[278]
"Nature changes a plant or animal's surroundings gradually--man
sometimes does so suddenly. All botanists know that plants vary so
greatly under domestication that in time they become hardly
recognizable. They undergo so much change that botanists do not at all
like describing domesticated varieties. Wheat itself is an example.
Where can wheat be found as a wild plant, unless it have escaped from
some neighbouring cultivation? Where are our cauliflowers, our lettuces,
to be found wild, with the same characters as they possess in our
kitchen gardens?
"The same applies to our domesticated breeds of animals. What a variety
of breeds has not man produced among fowls and pigeons, of which we can
find no undomesticated examples!"[279]
The foregoing remarks on the effects of domestication seem to have been
inspired by those given p. 123 and pp. 168, 169 of this volume.[280]
"Some, doubtless, have changed less than others, owing to their having
undergone a less protracted domestication, and a less degree of change
in climate; nevertheless, though our ducks and geese, for example, are
of the same type as their wild progenitors, they have lost the power of
long and sustained flight, and have become in other respects
considerably modified.[281]
"A bird, after having been kept five or six years in a cage, cannot on
being liberated fly like its brethren which have been always free. Such
a change in a single lifetime has not effected any transmissible
modification of type; but captivity, continued during many successive
generations, would undoubtedly do so. If to the effects of captivity
there be added also those of changed climate, changed food, and changed
actions for the purpose of laying hold of food, these, united together
and become constant, would in the course of time develop an entirely new
breed."
This, again, is almost identical with the passage from Buffon,[282] p.
148 of this volume. See also pp. 169, 170.
"Where can our many domestic breeds of dogs be found in a wild state?
Where are our bulldogs, greyhounds, spaniels, and lapdogs, breeds
presenting differences which, in wild animals, would be certainly called
specific? These are all descended from an animal nearly allied to the
wolf, if not from the wolf itself. Such an animal was domesticated by
early man, taken at successive intervals into widely different climates,
trained to different habits, carried by man in his migrations as a
precious capital into the most distant countries, and crossed from time
to time with other breeds which had been developed in similar ways.
Hence our present multiform breeds."[283]
Here, also, it is impossible to forget Buffon's passages on the dog,
given pp. 121, 122. See also p. 223.
"Observe the gradations which are found between the _ranunculus
aquatilis_ and the _ranunculus hederaceus_: the latter--a land
plant--resembles those parts of the former which grow above the surface
of the water, but not those that grow beneath it.[284]
"The modifications of animals arise more slowly than those of plants;
they are therefore less easily watched, and less easily assignable to
their true causes, but they arise none the less surely. As regards these
causes, the most potent is diversity of the surroundings in which they
exist, but there are also many others.[285]
"The climate of the same place changes, and the place itself changes
with changed climate and exposure, but so slowly that we imagine all
lands to be stable in their conditions. This, however, is not true;
climatic and other changes induce corresponding changes in environment
and habit, and these modify the structure of the living forms which are
subjected to them. Indeed, we see intermediate forms and species
corresponding to intermediate conditions.
"To the above causes must be ascribed the infinite variety of existing
forms, independently of any tendency towards progressive
development."[286]
The reader has now before him a fair sample of "the well-known doctrine
of inherited habit as advanced by Lamarck."[287] In what way, let me ask
in passing, does "the case of neuter insects" prove "demonstrative"
against it, unless it is held equally demonstrative against Mr. Darwin's
own position? Lamarck continues:--
"The character of any habitable quarter of the globe is _qua_ man
constant: the constancy of type in species is therefore also _qua_ man
persistent. But this is an illusion. We establish, therefore, the three
following propositions:--
"1. That every considerable and sustained change in the surroundings of
any animal involves a real change in its needs.
"2. That such change of needs involves the necessity of changed action
in order to satisfy these needs, and, in consequence, of new
habits.[288]
"3. It follows that such and such parts, formerly less used, are now
more frequently employed, and in consequence become more highly
developed; new parts also become insensibly evolved in the creature by
its own efforts from within.
"From the foregoing these two general laws may be deduced:--
"_Firstly. That in every animal which has not passed its limit of
development, the more frequent and sustained employment of any organ
develops and aggrandizes it, giving it a power proportionate to the
duration of its employment, while the same organ in default of constant
use becomes insensibly weakened and deteriorated, decreasing
imperceptibly in power until it finally disappears._[289]
"_Secondly. That these gains or losses of organic development, due to
use or disuse, are transmitted to offspring, provided they have been
common to both sexes, or to the animals from which the offspring have
descended._"[290]
Lamarck now sets himself to establish the fact that animals have
developed modifications which have been transmitted to their offspring.
"Naturalists," he says, "have believed that the possession of certain
organs has led to their employment. This is not so: it is need and use
which have developed the organs, and even called them into existence."
[I have already sufficiently insisted that it is impossible to dispense
with either of these two views. Demand and Supply have gone hand in
hand, each reacting upon the other.] "Otherwise a special act of
creation would be necessary for every different combination of
conditions; and it would be also necessary that the conditions should
remain always constant.
"If this were really so we should have no racehorses like those of
England, nor drayhorses so heavy in build and so unlike the racehorse;
for there are no such breeds in a wild state. For the same reason, we
should have no turnspit dogs with crooked legs, no greyhounds nor
water-spaniels; we should have no tailless breed of fowls nor fantail
pigeons, &c. Nor should we be able to cultivate wild plants in our
gardens, for any length of time we please, without fear of their
changing.
"'Habit,' says the proverb, 'is a second nature'; what possible meaning
can this proverb have, if descent with modification is unfounded?[291]
"As regards the circumstances which give rise to variation, the
principal are climatic changes, different temperatures of any of a
creature's environments, differences of abode, of habit, of the most
frequent actions; and lastly, of the means of obtaining food,
self-defence, reproduction, &c., &c."[292]
Here we have absolute agreement with Dr. Erasmus Darwin,[293] except
that there seems a tendency in this passage to assign more effect to the
direct action of conditions than is common with Lamarck. He seems to be
mixing Buffon and Dr. Darwin.
"In consequence of change in any of these respects, the faculties of an
animal become extended and enlarged by use: they become diversified
through the long continuance of the new habits, until little by little
their whole structure and nature, as well as the organs originally
affected, participate in the effects of all these influences, and are
modified to an extent which is capable of transmission to
offspring."[294]
This sentence alone would be sufficient to show that Lamarck was as much
alive as Buffon and Dr. Darwin were before him, to the fact that one of
the most important conditions of an animal's life, is the relation in
which it stands to the other inhabitants of the same neighbourhood--from
which the survival of the fittest follows as a self-evident proposition.
Nothing, therefore, can be more unfounded than the attempt, so
frequently made by writers who have not read Lamarck, or who think
others may be trusted not to do so, to represent him as maintaining
something perfectly different from what is maintained by modern writers
on evolution. The difference, in so far as there is any difference, is
one of detail only. Lamarck would not have hesitated to admit, that, if
animals are modified in a direction which is favourable to them, they
will have a better chance of surviving and transmitting their
favourable modifications. In like manner, our modern evolutionists
should allow that animals are modified not because they subsequently
survive, but because they have done this or that which has led to their
modification, and hence to their surviving.
Having established that animals and plants are capable of being
materially changed in the course of a few generations, Lamarck proceeds
to show that their modification is due to changed distribution of the
use and disuse of their organs at any given time.
"_The disuse of an organ_," he writes, "_if it becomes constant in
consequence of new habits, gradually reduces the organ, and leads
finally to its disappearance_."[295]
"Thus whales have lost their teeth, though teeth are still found in the
embryo. So, again, M. Geoffroy has discovered in birds the groove where
teeth were formerly placed. The ant-eater, which belongs to a genus that
has long relinquished the habit of masticating its food, is as toothless
as the whale."[296]
Then are adduced further examples of rudimentary organs, which will be
given in another place, and need not be repeated here. Speaking of the
fact, however, that serpents have no legs, though they are higher in the
scale of life than the batrachians, Lamarck attributes this "to the
continued habit of trying to squeeze through very narrow places, where
four feet would be in the way, and would be very little good to them,
inasmuch as more than four would be wanted in order to turn bodies that
were already so much elongated."[297]
If it be asked why, on Lamarck's theory, if serpents wanted more legs
they could not have made them, the answer is that the attempt to do this
would be to unsettle a question which had been already so long settled,
that it would be impossible to reopen it. The animal must adapt itself
to four legs, or must get rid of all or some of them if it does not like
them; but it has stood so long committed to the theory that if there are
to be legs at all, there are to be not more than four, that it is
impossible for it now to see this matter in any other light.
The experiments of M. Brown Sequard on guinea pigs, quoted by Mr.
Darwin,[298] suggest that the form of the serpent may be due to its
having lost its legs by successive accidents in squeezing through narrow
places, and that the wounds having been followed by disease, the
creature may have bitten the limbs off, in which case the loss might
have been very readily transmitted to offspring; the animal would
accordingly take to a sinuous mode of progression that would doubtless
in time elongate the body still further. M. Brown Sequard "carefully
recorded" thirteen cases, and saw even a greater number, in which the
loss of toes by guinea pigs which had gnawed their own toes off, was
immediately transmitted to offspring. Accidents followed by disease seem
to have been somewhat overlooked as a possible means of modification.
The missing forefinger to the hand of the potto[299] would appear at
first sight to have been lost by some such mishap. Returning to Lamarck,
we find him saying:--
"Even in the lifetime of a single individual we can see organic changes
in consequence of changed habits. Thus M. Tenon has constantly found the
intestinal canal of drunkards to be greatly shorter than that of people
who do not drink. This is due to the fact that habitual drunkards eat
but little solid food, so that the stomach and intestines are more
rarely distended. The same applies to people who lead studious and
sedentary lives. The stomachs of such persons and of drunkards have
little power, and a small quantity will fill them, while those of men
who take plenty of exercise remain in full vigour and are even
increased."[300]
It becomes now necessary to establish the converse proposition, namely
that:--
"_The frequent use of an organ increases its power; it even develops the
organ itself, and makes it acquire dimensions and powers which it is not
found to have in animals which make no use of such an organ._
"In support of this we see that the bird whose needs lead it to the
water, in which to find its prey, extends the toes of its feet when it
wants to strike the water, and move itself upon the surface. The skin at
the base of the toes of such a bird contracts the habit of extending
itself from continual practice. To this cause, in the course of time,
must be attributed the wide membrane which unites the toes of ducks,
geese, &c. The same efforts to swim, that is to say, to push the water
for the purpose of moving itself forward, has extended the membrane
between the toes of frogs, turtles, the otter, and the beaver."[301]
[This is taken, I believe, from Dr. Darwin or Buffon, but I have lost
the passage, if, indeed, I ever found it. It had been met by Paley some
years earlier (1802) in the following:--
"There is nothing in the action of swimming as carried on by a bird upon
the surface of the water that should generate a membrane between the
toes. As to that membrane it is an action of constant resistance.... The
web feet of amphibious quadrupeds, seals, otters, &c., fall under the
same observation."[302]]
"On the other hand those birds whose habits lead them to perch on trees,
and which have sprung from parents that have long contracted this habit,
have their toes shaped in a perfectly different manner. Their claws
become lengthened, sharpened, and curved, so as to enable the creature
to lay hold of the boughs on which it so often rests. The shore bird
again, which does not like to swim, is nevertheless continually obliged
to enter the water when searching after its prey. Not liking to plunge
its body in the water, it makes every endeavour to extend and lengthen
its lower limbs. In the course of long time these birds have come to be
elevated, as it were, on stilts, and have got long legs bare of feathers
as far as their thighs, and often still higher. The same bird is
continually trying to extend its neck in order to fish without wetting
its body, and in the course of time its neck has become modified
accordingly.[303]
"Swans, indeed, and geese have short legs and very long necks, but this
is because they plunge their heads as low in the water as they can in
their search for aquatic larvae and other animalcules, but make no effort
to lengthen their legs."[304]
This too is taken from some passage which I have either never seen or
have lost sight of. Paley never gives a reference to an opponent, though
he frequently does so when quoting an author on his own side, but I can
hardly doubt that he had in his mind the passage from which Lamarck in
1809 derived the foregoing, when in 1802 he wrote Sec. 5 of chapter xv. and
the latter half of chapter xxiii. of his 'Natural Theology.'
"The tongues of the ant-eater and the woodpecker," continues Lamarck,
"have become elongated from similar causes. Humming birds catch hold of
things with their tongues; serpents and lizards use their tongues to
touch and reconnoitre objects in front of them, hence their tongues have
come to be forked.
"Need--always occasioned by the circumstances in which an animal is
placed, and followed by sustained efforts at gratification--can not only
modify an organ, that is to say, augment or reduce it, but can change
its position when the case requires its removal.[305]
"Ocean fishes have occasion to see what is on either side of them, and
have their eyes accordingly placed on either side their head. Some
fishes, however, have their abode near coasts on submarine banks and
inclinations, and are thus forced to flatten themselves as much as
possible in order to get as near as they can to the shore. In this
situation they receive more light from above than from below, and find
it necessary to pay attention to whatever happens to be above them; this
need has involved the displacement of their eyes, which now take the
remarkable position which we observe in the case of soles, turbots,
plaice, &c. The transfer of position is not even yet complete in the
case of these fishes, and the eyes are not, therefore, symmetrically
placed; but they are so with the skate, whose head and whole body are
equally disposed on either side a longitudinal section. Hence the eyes
of this fish are placed symmetrically upon the uppermost side.[306]
"The eyes of serpents are placed on the sides and upper portions of the
head, so that they can easily see what is on one side of them or above
them; but they can only see very little in front of them, and supplement
this deficiency of power with their tongue, which is very long and
supple, and is in many kinds so divided that it can touch more than one
object at a time; the habit of reconnoitring objects in front of them
with their tongues has even led to their being able to pass it through
the end of their nostrils without being obliged to open their jaws.[307]
"Herbivorous mammals, such as the elephant, rhinoceros, ox, buffalo,
horse, &c., owe their great size to their habit of daily distending
themselves with food and taking comparatively little exercise. They
employ their feet for standing, walking, or running, but not for
climbing trees. Hence the thick horn which covers their toes. These toes
have become useless to them, and are now in many cases rudimentary only.
Some pachyderms have five toes covered with horn; some four, some
three. The ruminants, which appear to be the earliest mammals that
confined themselves to a life upon the ground, have but two hooves,
while the horse has only one.[308]
"Some herbivorous animals, especially among the ruminants, have been
incessantly preyed upon by carnivorous animals, against which their only
refuge is in flight. Necessity has therefore developed the light and
active limbs of antelopes, gazelles, &c. Ruminants, only using their
jaws to graze with, have but little power in them, and therefore
generally fight with their heads. The males fight frequently with one
another, and their desires prompt an access of fluids to the parts of
their heads with which they fight; thus the horns and bosses have arisen
with which the heads of most of these animals are armed.[309] The
giraffe owes its long neck to its continued habit of browsing upon
trees, whence also the great length of its fore legs as compared with
its hinder ones. Carnivorous animals, in like manner, have had their
organs modified in correlation with their desires and habits. Some
climb, some scratch in order to burrow in the earth, some tear their
prey; they therefore have need of toes, and we find their toes separated
and armed with claws. Some of them are great hunters, and also plunge
their claws deeply into the bodies of their victims, trying to tear out
the part on which they have seized; this habit has developed a size and
curvature of claw which would impede them greatly in travelling over
stony ground; they have therefore been obliged to make efforts to draw
back their too projecting claws, and so, little by little, has arisen
the peculiar sheath into which cats, tigers, lions, &c., withdraw their
claws when they no longer wish to use them.[310]
"We see then that the long-sustained and habitual exercise of any part
of a living organism, in consequence of the necessities engendered by
its environment, develops such part, and gives it a form which it would
never have attained if the exercise had not become an habitual action.
All known animals furnish us with examples of this.[311] If anyone
maintains that the especially powerful development of any organ has had
nothing to do with its habitual use--that use has added nothing, and
disuse detracted nothing from its efficiency, but that the organ has
always been as we now see it from the creation of the particular species
onwards--I would ask why cannot our domesticated ducks fly like wild
ducks? I would also quote a multitude of examples of the effects of use
and disuse upon our own organs, effects which, if the use and disuse
were constant for many generations, would become much more marked.
"A great number of facts show, as will be more fully insisted on, that
when its will prompts an animal to this or that action, the organs which
are to execute it receive an excess of nervous fluid, and this is the
determinant cause of the movements necessary for the required action.
Modifications acquired in this way eventually become permanent in the
breed that has acquired them, and are transmitted to offspring, without
the offspring's having itself gone through the processes of acquisition
which were necessary in the case of the ancestor.[312] Frequent crosses,
however, with unmodified individuals, destroy the effect produced. It is
only owing to the isolation of the races of man through geographical and
other causes, that man himself presents so many varieties, each with a
distinctive character.
"A review of all existing classes, orders, genera, and species would
show that their structure, organs, and faculties, are in all cases
solely attributable to the surroundings to which each creature has been
subjected by nature, and to the habits which individuals have been
compelled to contract; and that they are not at all the result of a form
originally bestowed, which has imposed certain habits upon the
creature.[313]
"It is unnecessary to multiply instances; the fact is simply this, that
all animals have certain habits, and that their organization is always
in perfect harmony with these habits.[314] The conclusion hitherto
accepted is that the Author of Nature, when he created animals, foresaw
all the possible circumstances in which they would be placed, and gave
an unchanging organism to each creature, in accordance with its future
destiny. The conclusion, on the other hand, here maintained is that
nature has evolved all existing forms of life successively, beginning
with the simplest organisms and gradually proceeding to those which are
more complete. Forms of life have spread themselves throughout all the
habitable parts of the earth, and each species has received its habits
and corresponding modification of organs, from the influence of the
surroundings in which it found itself placed.[315]
"The first conclusion supposes an unvarying organism and unvarying
conditions. The second, which is my theory (_la mienne propre_),
supposes that each animal is capable of modifications which in the
course of generations amount to a wide divergence of type.
"If a single animal can be shown to have varied considerably under
domestication, the first conclusion is proved to be inadmissible, and
the second to be in conformity with the laws of nature."
This is a milder version of Buffon's conclusion (see _ante_, pp. 90,
91). It is a little grating to read the words "la mienne propre,"
and to recall no mention of Buffon in the 'Philosophie Zoologique.'
"Animal forms then are the result of conditions of life and of the
habits engendered thereby. With new forms new faculties are developed,
and thus nature has little by little evolved the existing
differentiations of animal and vegetable life."[316]
Lamarck makes no exception in man's favour to the rule of descent with
modification. He supposes that a race of quadrumanous apes gradually
acquired the upright position in walking, with a corresponding
modification of the feet and facial angle. Such a race having become
master of all the other animals, spread itself over all parts of the
world that suited it. It hunted out the other higher races which were in
a condition to dispute with it for enjoyment of the world's
productions, and drove them to take refuge in such places as it did not
desire to occupy. It checked the increase of the races nearest itself,
and kept them exiled in woods and desert places, so that their further
development was arrested, while itself, able to spread in all
directions, to multiply without opposition, and to lead a social life,
it developed new requirements one after another, which urged it to
industrial pursuits, and gradually perfected its capabilities.
Eventually this pre-eminent race, having acquired absolute supremacy,
came to be widely different from even the most perfect of the lower
animals.
"Certain apes approach man more nearly than any other animal approaches
him; nevertheless, they are far inferior to him, both in bodily and
mental capacity. Some of them frequently stand upright, but as they do
not habitually maintain this attitude, their organization has not been
sufficiently modified to prevent it from being irksome to them to stand
for long together. They fall on all fours immediately at the approach of
danger. This reveals their true origin.[317]
"But is the upright position altogether natural, even to man? He uses it
in moving from place to place, but still standing is a fatiguing
position, and one which can only be maintained for a limited time, and
by the aid of muscular contraction. The vertebrate column does not pass
through the axis of the head so as to maintain it in like equilibrium
with other limbs. The head, chest, stomach, and intestines weigh almost
entirely on the anterior part of the vertebrate column, and this column
itself is placed obliquely, so that, as M. Richerand has observed,
continual watchfulness and muscular exertion are necessary to avoid the
falls towards which the weight and disposition of our parts are
continually inclining us. 'Children,' he remarks, 'have a constant
tendency to assume the position of quadrupeds.'"[318]
"Surely these facts should reveal man's origin as analogous to that of
the other mammals, if his organization only be looked to. But the
following consideration must be added. New wants, developed in societies
which had become numerous, must have correspondingly multiplied the
ideas of this dominant race, whose individuals must have therefore
gradually felt the need of fuller communication with each other. Hence
the necessity for increasing and varying the number of the signs
suitable for mutual understanding. It is plain therefore that incessant
efforts would be made in this direction.[319]
"The lower animals, though often social, have been kept in too great
subjection for any such development of power. They continue, therefore,
stationary as regards their wants and ideas, very few of which need be
communicated from one individual to another. A few movements of the
body, a few simple cries and whistles, or inflexions of voice, would
suffice for their purpose. With the dominant race, on the other hand,
the continued multiplication of ideas which it was desirable to
communicate rapidly, would exhaust the power of pantomimic gesture and
of all possible inflexions of the voice--therefore by a succession of
efforts this race arrived at the utterance of articulate sounds. A few
only would be at first made use of, and these would be supplemented by
inflexions of the voice: presently they would increase in number,
variety, and appropriateness, with the increase of needs and of the
efforts made to speak. Habitual exercise would increase the power of the
lips and tongue to articulate distinctly.
"The diversity of language is due to geographical distribution, with
consequent greater or less isolation of certain races, and corruption of
the signs originally agreed upon for each idea. Man's own wants,
therefore, will have achieved the whole result. They will have given
rise to endeavour, and habitual use will have developed the organs of
articulation."[320]
How, let me ask again, is "the case of neuter insects" "demonstrative"
against the "well-known" theory put forward in the foregoing chapter?
FOOTNOTES:
[208] 'Phil. Zool.,' tom. i., edited by M. Martins, 1873, pp. 25, 26.
[209] 'Phil. Zool.' tom. i. pp. 26, 27.
[210] Page 28.
[211] Pages 28-31.
[212] 'Phil. Zool.,' tom. i. pp. 34, 35.
[213] Page 42.
[214] Page 46.
[215] 'Phil. Zool.,' tom. i. p. 50.
[216] Pages 50, 51.
[217] 'Origin of Species,' p. 395, ed. 1876.
[218] 'Phil. Zool.,' tom. i. p. 61.
[219] 'Phil. Zool.,' tom. i. p. 62.
[220] Page 63.
[221] Page 64.
[222] Page 65.
[223] Page 67.
[224] Chap. iii.
[225] 'Phil. Zool.,' tom. i. p. 72.
[226] Pages 71-73.
[227] 'Phil. Zool.,' tom. i. p. 74, 75.
[228] 'Phil. Zool.,' tom. i. pp. 75-77.
[229] 'Origin of Species,' p. 104, ed. 1876.
[230] 'Phil. Zool.,' tom. i. p. 79.
[231] 'Phil. Zool.,' tom. i. pp. 79, 80.
[232] 'Phil. Zool.,' tom. i. p. 80.
[233] Page 80.
[234] Ed. 1876.
[235] 'Phil. Zool.,' tom. i. p. 81.
[236] 'Origin of Species,' p. 241.
[237] 'Phil. Zool.,' p. 82.
[238] 'Phil. Zool.,' tom. i. p. 83.
[239] Pages 349-351.
[240] Page 84.
[241] 'Phil. Zool.,' tom. i. p. 88.
[242] Page 90.
[243] 'Origin of Species,' p. 3.
[244] 'Phil. Zool.,' tom. i. p. 94.
[245] Pages 95-96.
[246] Page 97.
[247] Phil. Zool.,' tom. i. p. 98.
[248] 'Phil. Zool.,' tom. i. p. 111.
[249] 'Phil. Zool.,' tom. i. p. 112.
[250] See pp. 227 and 259 of this book.
[251] 'Phil. Zool.,' tom. i. p. 113.
[252] Page 113.
[253] 'Phil Zool.,' tom. i. p. 113.
[254] This passage is rather obscure. I give it therefore in the
original:--
"Ainsi les naturalistes ayant remarque que beaucoup d'especes, certains
genres, et meme quelques familles paraissent dans une sorte d'isolement,
quant a leurs caracteres, plusieurs se sont imagines que les etres
vivants, dans l'un ou l'autre regne, s'avoisinaient, ou s'eloignaient
entre eux, relativement a leurs _rapports naturels_, dans une
disposition semblable aux differents points d'une carte de geographie ou
d'une mappemonde. Ils regardent les petites series bien prononcees qu'on
a nommees familles naturelles, comme devant etre disposees entre elles
de maniere a former une reticulation. Cette idee qui a paru sublime a
quelques modernes, est evidemment une erreur, et, sans doute, elle se
dissipera des qu'on aura des connaissances plus profondes et plus
generales de l'organisation, et surtout lorsqu'on distinguera ce qui
appartient a l'influence des lieux d'habitation et des habitudes
contractees, de ce qui resulte des progres plus ou moins avances dans la
composition ou le perfectionnement de l'organisation."--(p. 120).
[255] 'Origin of Species,' pp. 265, 266.
[256] 'Phil. Zool.,' tom. i. p. 121.
[257] 'Phil. Zool.,' tom. i. p. 122.
[258] 'Origin of Species,' pp. 122, 123.
[259] 'Phil. Zool.,' tom. i. p. 123.
[260] 'Phil. Zool.,' tom. i. p. 123.
[261] 'Origin of Species,' chap. xiv.
[262] 'Phil. Zool.,' tom. i. p. 123.
[263] 'Phil. Zool.,' tom. i. p. 140.
[264] Page 142.
[265] Page 143.
[266] 'Phil. Zool.,' tom. i. p. 143.
[267] Page 144.
[268] Ibid.
[269] 'Phil. Zool.,' tom. i. p. 145.
[270] Page 146.
[271] 'Phil. Zool.,' tom. i. p. 221.
[272] Page 222.
[273] 'Phil. Zool.,' tom. i. p. 223.
[274] Page 224.
[275] Page 223.
[276] Page 225.
[277] 'Phil. Zool.,' tom. i. p. 225.
[278] Page 226.
[279] 'Phil. Zool.,' tom. i. p. 228.
[280] See Buffon, 'Hist. Nat.,' tom. v. pp. 196, 197, and Supp. tom. v.
pp. 250-253.
[281] 'Phil. Zool.,' tom. i. p. 229.
[282] 'Hist. Nat.,' tom. xi. p. 290.
[283] 'Phil. Zool.,' tom. i. p. 231.
[284] Page 231. See Dr. Darwin's note on _Trapa natans_, 'Botanic
Garden,' part ii. canto 4, l. 204.
[285] 'Phil. Zool.,' tom. i. p. 232.
[286] Page 233. See Buffon on Climate, tom. ix., 'The Animals of the Old
and New Worlds.'
[287] 'Origin of Species,' p. 233, ed. 1876.
[288] 'Phil. Zool.,' tom. i. p 234.
[289] Page 235.
[290] Page 236.
[291] 'Phil. Zool.,' tom. i. p. 237.
[292] Page 238.
[293] See _ante_, pp. 220-228.
[294] 'Phil. Zool.,' tom. i. p. 239.
[295] 'Phil. Zool.,' tom. i. p 240.
[296] Page 241.
[297] Page 245.
[298] 'Animals and Plants under Domestication,' vol. i. p. 467, &c.
[299] See frontispiece to Professor Mivart's 'Genesis of Species.'
[300] 'Phil. Zool.,' tom. i. p. 247.
[301] Page 248.
[302] 'Nat. Theol.,' vol. xii., end of Sec. viii.
[303] 'Phil. Zool.,' tom. i. p. 249.
[304] 'Phil. Zool.,' tom. i. p. 250.
[305] Page 250.
[306] 'Phil. Zool.,' tom. i. p. 251.
[307] Page 252.
[308] 'Phil. Zool.,' tom. i. p. 253.
[309] Page 254.
[310] 'Phil. Zool.,' tom. i. p. 256.
[311] Page 257.
[312] 'Phil. Zool.,' tom. i. p. 259.
[313] Page 260.
[314] Page 263.
[315] 'Phil. Zool.,' tom. i. p. 263.
[316] Page 265.
[317] 'Phil. Zool.,' tom. i. p. 343.
[318] 'Phil. Zool.,' tom. i. p. 343.
[319] Page 346.
[320] 'Phil. Zool.,' tom. i. p. 347.