Chapter IV (2)

"As regards habits, it is curious to observe the results in the
special form and height of the giraffe (_camelopardalis_); we know
that this animal, the tallest of mammals, inhabits the interior of
Africa, and that it lives in localities where the earth, almost
always arid and destitute of herbage, obliges it to browse on the
foliage of trees, and to make continual efforts to reach it. It has
resulted from this habit, maintained for a long period in all the
individuals of its race, that its forelegs have become longer than
the hinder ones, and that its neck is so elongated that the
giraffe, without standing on its hind legs, raises its head and
reaches six meters in height (almost twenty feet).

"Among the birds, the ostriches, deprived of the power of flight,
and raised on very long legs, probably owe their singular
conformation to analogous circumstances.

"The result of habits is as remarkable in the carnivorous mammals as
it is in the herbivorous, but it presents effects of another kind.

"Indeed, those of these mammals which are habituated, as their race,
both to climb as well as to scratch or dig in the ground, or to tear
open and kill other animals for food, have been obliged to use the
digits of their feet; moreover, this habit has favored the
separation of their digits, and has formed the claws with which they
are armed.

"But among the carnivores there are some which are obliged to run in
order to overtake their prey; moreover, since these need and
consequently have the habit of daily tearing with their claws and
burying them deeply in the body of another animal, to seize and then
to tear the flesh, and have been enabled by their repeated efforts
to procure for these claws a size and curvature which would greatly
interfere in walking or running on stony soil, it has resulted in
this case that the animal has been obliged to make other efforts to
draw back these too salient and curved claws which would impede it,
and hence there has resulted the gradual formation of those special
sheaths in which the cats, tigers, lions, etc., withdraw their claws
when not in action.

"Thus the efforts in any direction whatever, maintained for a long
time or made habitually by certain parts of a living body to satisfy
necessities called out by nature or by circumstances, develop these
parts and make them acquire dimensions and a shape which they never
would have attained if these efforts had not become the habitual
action of the animals which have exercised them. The observations
made on all the animals known will everywhere furnish examples.

"Can any of them be more striking than that which the _kangaroo_
offers us? This animal, which carries its young in its abdominal
pouch, has adopted the habit of holding itself erect, standing only
on its hind feet and tail, and only changing its position by a
series of leaps, in which it preserves its erect attitude so as not
to injure its young.

"Let us see the result:

"1. Its fore legs, of which it makes little use, and on which it
rests only during the instant when it leaves its erect attitude,
have never reached a development proportionate to that of the other
parts, and have remained thin, very small, and weak;

"2. The hind legs, almost continually in action, both for supporting
the body and for leaping, have, on the contrary, obtained a
considerable development, and have become very large and strong;

"3. Finally, the tail, which we see is of much use in supporting the
animal and in the performance of its principal movements, has
acquired at its base a thickness and a strength extremely
remarkable.

"These well-known facts are assuredly well calculated to prove what
results from the habitual use in the animals of any organ or part;
and if, when there is observed in an animal an organ especially well
developed, strong, and powerful, it is supposed that its habitual
use has not produced it, that its continual disuse will make it lose
nothing, and, finally, that this organ has always been such since
the creation of the species to which this animal belongs, I will ask
why our domestic ducks cannot fly like wild ducks--in a word, I
might cite a multitude of examples which prove the differences in us
resulting from the exercise or lack of use of such of our organs,
although these differences might not be maintained in the
individuals which follow them genetically, for then their products
would be still more considerable.

"I shall prove, in the second part, that when the will urges an
animal to any action, the organs which should execute this action
are immediately provoked by the affluence of subtile fluids (the
nervous fluid), which then become the determining cause which calls
for the action in question. A multitude of observations prove this
fact, which is now indisputable.

"It results that the multiplied repetitions of these acts of
organization strengthen, extend, develop, and even create the organs
which are necessary. It is only necessary attentively to observe
that which is everywhere occurring to convince ourselves of the
well-grounded basis of this cause of organic developments and
changes.

"Moreover, every change acquired in an organ by a habit of use
sufficient to have produced it is then preserved by heredity
(_génération_) if it is common to the individuals which, in
fecundation, unite in the reproduction of their species. Finally,
this change is propagated, and thus is transmitted to all the
individuals which succeed and which are submitted to the same
circumstances, unless they have been obliged to acquire it by the
means which have in reality created it.

"Besides, in reproductive unions the crossings between the
individuals which have different qualities or forms are necessarily
opposed to the continuous propagation of these qualities and these
forms. We see that in man, who is exposed to so many diverse
circumstances which exert an influence on him, the qualities or the
accidental defects which he has been in the way of acquiring, are
thus prevented from being preserved and propagated by generation.
If, when some particular features of form or any defects are
acquired, two individuals under this condition should always pair,
they would reproduce the same features, and the successive
generations being confined to such unions, a special and distinct
race would then be formed. But perpetual unions between individuals
which do not have the same peculiarities of form would cause all the
characteristics acquired by special circumstances to disappear.

"From this we can feel sure that if distances of habitation did not
separate men the intermixture by generation would cause the general
characteristics which distinguish the different nations to
disappear.

"If I should choose to pass in review all the classes, all the
orders, all the genera, and all the species of animals which exist,
I should show that the structure of individuals and their parts,
their organs, their faculties, etc., etc., are in all cases the sole
result of the circumstances in which each species is found to be
subjected by nature and by the habits which the individuals which
compose it have been obliged to contract, and which are only the
product of a power primitively existing, which has forced the
animals into their well-known habits.

"We know that the animal called the _ai_, or the sloth (_Bradypus
tridactylus_), is throughout life in a condition so very feeble that
it is very slow and limited in its movements, and that it walks on
the ground with much difficulty. Its movements are so slow that it
is thought that it cannot walk more than fifty steps in a day. It is
also known that the structure of this animal is in direct relation
with its feeble state or its inaptitude for walking; and that should
it desire to make any other movements than those which it is seen to
make, it could not do it.

"Therefore, supposing that this animal had received from nature its
well-known organization, it is said that this organization has
forced it to adopt the habits and the miserable condition it is in.

"I am far from thinking so; because I am convinced that the habits
which the individuals of the race of the _ai_ were originally
compelled to contract have necessarily brought their organization
into its actual state.

"Since continual exposure to dangers has at some time compelled the
individuals of this species to take refuge in trees and to live in
them permanently, and then feed on their leaves, it is evident that
then they would give up making a multitude of movements that animals
which live on the ground perform.

"All the needs of the _ai_ would then be reduced to seizing hold of
the branches, to creeping along them or to drawing them in so as to
reach the leaves, and then to remain on the tree in a kind of
inaction, so as to prevent falling. Besides, this kind of
sluggishness would be steadily provoked by the heat of the climate;
for in warm-blooded animals the heat urges them rather to repose
than to activity.

"Moreover, during a long period of time the individuals of the race
of the _ai_ having preserved the habit of clinging to trees and of
making only slow and slightly varied movements, just sufficient for
their needs, their organization has gradually become adapted to
their new habits, and from this it will result:

"1. That the arms of these animals making continual efforts readily
to embrace the branches of trees, would become elongated;

"2. That the nails of their digits would acquire much length and a
hooked shape, by the continued efforts of the animal to retain its
hold;

"3. That their digits never having been trained to make special
movements, would lose all mobility among themselves, would become
united, and would only preserve the power of bending or of
straightening out all together;

"4. That their thighs, continually embracing both the trunks and the
larger branches of trees, would contract a condition of habitual
separation which would tend to widen the pelvis and to cause the
cotyloid cavities to be directed backward;

"5. Finally, that a great number of their bones would become fused,
and hence several parts of their skeleton would assume an
arrangement and a figure conformed to the habits of these animals,
and contrary to what would be necessary for them to have for other
habits.

"Indeed, this can never be denied, because, in fact, nature on a
thousand other occasions shows us, in the power exercised by
circumstances on habits, and in that of the influence of habits on
forms, dispositions, and the proportion of the parts of animals,
truly analogous facts.

"A great number of citations being unnecessary, we now see to what
the case under discussion is reduced.

"The fact is that divers animals have each, according to their genus
and their species, special habits, and in all cases an organization
which is perfectly adapted to these habits.

"From the consideration of this fact, it appears that we should be
free to admit either one or the other of the following conclusions,
and that only one of them is susceptible of proof.

"_Conclusion admitted up to this day_: Nature (or its Author), in
creating the animals, has foreseen all the possible kinds of
circumstances in which they should live, and has given to each
species an unchanging organization, as also a form determinate and
invariable in its different parts, which compels each species to
live in the places and in the climate where we find it, and has
there preserved its known habits.

"_My own conclusion_: Nature, in producing in succession every
species of animal, and beginning with the least perfect or the
simplest to end her work with the most perfect, has gradually
complicated their structure; and these animals spreading generally
throughout all the inhabitable regions of the globe, each species
has received, through the influence of circumstances to which it has
been exposed, the habits which we have observed, and the
modifications in its organs which observation has shown us it
possesses.

"The first of these two conclusions is that believed up to the
present day--namely, that held by nearly every one; it implies, in
each animal, an unchanging organization and parts which have never
varied, and which will never vary; it implies also that the
circumstances of the places which each species of animal inhabits
will never vary in these localities; for should they vary, the same
animals could not live there, and the possibility of discovering
similar forms elsewhere, and of transporting them there, would be
forbidden.

"The second conclusion is my own: it implies that, owing to the
influence of circumstances on habits, and as the result of that of
habits on the condition of the parts and even on that of the
organization, each animal may receive in its parts and its
organization, modifications susceptible of becoming very
considerable, and of giving rise to the condition in which we find
all animals.

"To maintain that this second conclusion is unfounded, it is
necessary at first to prove that each point of the surface of the
globe never varies in its nature, its aspect, its situation whether
elevated or depressed, its climate, etc., etc.; and likewise to
prove that any part of animals does not undergo, even at the end of
a long period, any modification by changes of circumstances, and by
the necessity which directs them to another kind of life and action
than that which is habitual to them.

"Moreover, if a single fact shows that an animal for a long time
under domestication differs from the wild form from which it has
descended, and if in such a species in domesticity we find a great
difference in conformation between the individuals submitted to
such habits and those restricted to different habits, then it will
be certain that the first conclusion does not conform to the laws of
nature, and that, on the contrary, the second is perfectly in accord
with them.

"Everything combines then to prove my assertion--namely, that it is
not the form, either of the body or of its parts, which gives rise
to habits, and to the mode of life among animals; but that it is on
the contrary the habits, the manner of living, and all the other
influencing circumstances which have, after a time, constituted the
form of the body and of the parts of animals. With the new forms,
new faculties have been acquired, and gradually nature has come to
form the animals as we actually see them.

"Can there be in natural history a consideration more important, and
to which we should give more attention, than that which I have just
stated?

"We will end this first part with the principles and the exposition
of the natural classification of animals."

In the fourth chapter of the third part (vol. ii. pp. 276-301) Lamarck treats of the internal feelings of certain animals, which provoke wants (_besoins_). This is the subject which has elicited so much adverse criticism and ridicule, and has in many cases led to the wholesale rejection of all of Lamarck's views. It is generally assumed or stated by Lamarck's critics, who evidently did not read his book carefully, that while he claimed that the plants were evolved by the direct action of the physical factors, that in the case of all the animals the process was indirect. But this is not correct. He evidently, as we shall see, places the lowest animals, those without (or what he supposed to be without) a nervous system, in the same category as the plants. He distinctly states at the outset that only certain animals and man are endowed with this singular faculty, "which consists in being able to experience _internal emotions_ which provoke the wants and different external or internal causes, and which give birth to the power which enables them to perform different actions."

"The nervous fluid," he says, "can, then, undergo movements in certain parts of its mass, as well as in every part at once; moreover, it is these latter movements which constitute the _general movements_ (_ébranlements_) of this fluid, and which we now proceed to consider.

"The general movements of the nervous fluid are of two kinds;
namely,

"1. Partial movements (_ébranlements_), which finally become general
and end in a reaction. It is the movements of this sort which
produce feeling. We have treated of them in the third chapter.

"2. The movements which are general from the time they begin, and
which form no reaction. It is these which constitute internal
emotions, and it is of them alone of which we shall treat.

"But previously, it is necessary to say a word regarding the
_feeling of existence_, because this feeling is the source from
which the inner emotions originate.

"_On the Feeling of Existence._

"The feeling of existence (_sentiment d'existence_), which I shall
call _inner feeling_,[183] so as to separate from it the idea of a
general condition (_généralité_) which it does not possess, since it
is not common to all living beings and not even to all animals, is
a very obscure feeling, with which are endowed those animals
provided with a nervous system sufficiently developed to give them
the faculty of feeling.

"This sentiment, very obscure as it is, is nevertheless very
powerful, for it is the source of inner emotions which test
(_éprouvent_) the individuals possessing it, and, as the result,
this singular force urges these individuals to themselves produce
the movements and the actions which their wants require. Moreover
this feeling, considered as a very active _motor_, only acts thus by
sending to the muscles which necessarily cause these movements and
actions the nervous fluid which excites them....

"Indeed, as the result of organic or vital movements which are
produced in every animal, that which possesses a nervous system
sufficiently developed has physical sensibility and continually
receives in every inner and sensitive part impressions which
continually affect it, and which it feels in general without being
able to distinguish any single one.

"The sentiment of existence [consciousness] is general, since almost
every sensitive part of the body shares in it. 'It constitutes this
_me_ (_moi_) with which all animals, which are only sensitive, are
penetrated, without perceiving it, but which those possessing a
brain are able to notice, having the power of thought and of giving
attention to it. Finally, it is in all the source of a power which
is aroused by wants, which acts effectively only by emotion, and
through which the movements and actions derive the force which
produces them'....

"Finally, the inner feeling only manifests its power, and causes
movements, when there exists a system for muscular movement, which
is always dependent on the nervous system, and cannot take place
without it."

The author then states that these emotions of the organic sense may operate in the animals and in man either without or with an act of their will.

"From what has been said, we cannot doubt but that the inner and
general feeling which urges the animals possessing a nervous system
fitted for feeling should be susceptible of being aroused by the
causes which affect it; moreover, these causes are always the need
both of satisfying hunger, of escaping dangers, of avoiding pain, of
seeking pleasure, or that which is agreeable to the individual, etc.

"The emotions of the inner feeling can only be recognized by man,
who alone pays attention to them, but he only perceives those which
are strong, which excite his whole being, such as a view from a
precipice, a tragic scene, etc."

Lamarck then divides the emotions into physical and moral, the latter arising from our ideas, thoughts--in short, our intellectual acts--in the account of which we need not follow him.

In the succeeding chapter (V.) the author dilates on the force which causes actions in animals. "We know," he says "that plants can satisfy their needs without moving, since they find their food in the environing _milieux_. But it is not the same with animals, which are obliged to move about to procure their sustenance. Moreover, most of them have other wants to satisfy, which require other kinds of movements and acts." This matter is discussed in the author's often leisurely and prolix way, with more or less repetition, which we will condense.

The lowest animals--those destitute of a nervous system--move in response to a stimulus from without. Nature has gradually created the different organs of animals, varying the structure and situation of these organs according to circumstances, and has progressively improved their powers. She has begun by borrowing from without, so to speak--from the environment--the _productive force_, both of organic movements and those of the external parts. "She has thus transported this force [the result of heat, electricity, and perhaps others (p. 307)] into the animal itself, and, finally, in the most perfect animals she has placed a great part of this force at their disposal, as I will soon show."

This force incessantly introduced into the lowest animals sets in motion the visible fluids of the body and excites the irritability of their contained parts, giving rise to different contractile movements which we observe; hence the appearance of an irresistible propensity (_penchant_) which constrains them to execute those movements which by their continuity or their repetition give rise to habits.

The most imperfect animals, such as the _Infusoria_, especially the monads, are nourished by absorption and by "an internal inhibition of absorbed matters." "They have," he says, "no power of seeking their food, they have not even the power of recognizing it, but they absorb it because it comes in contact with every side of them (_avec tous les points de leur individu_), and because the water in which they live furnishes it to them in sufficient abundance."

"These frail animals, in which the subtile fluids of the environing _milieux_ constitute the stimulating cause of the orgasm, of irritability and of organic movements, execute, as I have said, contractile movements which, provoked and varied without ceasing by this stimulating cause, facilitate and hasten the absorptions of which I have just spoken." ...

_On the Transportation of the force-producing Movements in the Interior of Animals._

"If nature were confined to the employment of its first
means--namely, of a force entirely external and foreign to the
animal--its work would have remained very important; the animals
would have remained machines totally passive, and she would never
have given origin in any of these living beings to the admirable
phenomena of sensibility, of inmost feelings of existence which
result therefrom, of the power of action, finally, of ideas, by
which she can create the most wonderful of all, that of thought--in
a word, intelligence.

"But, wishing to attain these grand results, she has by slow degrees
prepared the means, in gradually giving consistence to the internal
parts of animals; in differentiating the organs, and in multiplying
and farther forming the fluids contained, etc., after which she has
transported into the interior of these animals that force productive
of movements and of actions which in truth it would not dominate at
first, but which she has come to place, in great part, at their
disposition when their organization should become very much more
perfect.

"Indeed, from the time that the animal organization had sufficiently
advanced in its structure to possess a nervous system--even slightly
developed, as in insects--the animals provided with this
organization were endowed with an intimate sense of their existence,
and from that time the force productive of movements was conveyed
into the very interior of the animal.

"I have already made it evident that this internal force which
produces movements and actions should derive its origin in the
intimate feeling of existence which animals with a nervous system
possess, and that this feeling, solicited or aroused by needs,
should then start into motion the subtile fluid contained in the
nerves and carry it to the muscles which should act, this producing
the actions which the needs require.

"Moreover, every want felt produces an emotion in the inner feeling
of the individual which experiences it; and from this emotion of the
feeling in question arises the force which gives origin to the
movement of the parts which are placed in activity....

"Thus, in the animals which possess the power of acting--namely, the
force productive of movements and actions--the inner feeling, which
on each occasion originates this force, being excited by some need,
places in action the power or force in question; excites the
movement of displacement in the subtile fluid of the nerves--which
the ancients called _animal spirits_; directs this fluid towards
that of its organs which any want impels to action; finally makes
this same fluid flow back into its habitual reservoirs when the
needs no longer require the organ to act.

"The inner feeling takes the place of the _will_; for it is now
important to consider that every animal which does not possess the
special organ in which or by which it executes thoughts, judgments,
etc., has in reality no will, does not make a choice, and
consequently cannot control the movements which its inner feeling
excites. _Instinct_ directs these actions, and we shall see that
this direction always results from emotions of the inner feeling, in
which intelligence has no part, and from the organization even which
the habits have modified, in such a manner that the needs of animals
which are in this category, being necessarily limited and always
the same in the same species, the inner feeling and, consequently,
the power of acting, always produces the same actions.

"It is not the same in animals which besides a nervous system have a
brain [the author meaning the higher vertebrates], and which make
comparisons, judgments, thoughts, etc. These same animals control
more or less their power of action according to the degree of
perfection of their brain; and although they are still strongly
subjected to the results of their habits, which have modified their
structure, they enjoy more or less freedom of the will, can choose,
and can vary their acts, or at least some of them."

Lamarck then treats of the consumption and exhaustion of the nervous fluid in the production of animal movements, resulting in fatigue.

He next occupies himself with the origin of the inclination to the same actions, and of instinct in animals.

"The cause of the well-known phenomenon which constrains almost all
animals to always perform the same acts, and that which gives rise
in man to a propensity (_penchant_) to repeat every action, becoming
habitual, assuredly merits investigation.

"The animals which are only 'sensible'[184]--namely, which possess
no brain, cannot think, reason, or perform intelligent acts, and
their perceptions being often very confused--do not reason and can
scarcely vary their actions. They are, then, invariably bound by
habits. Thus the insects, which of all animals endowed with feeling
have the least perfect nervous system,[185] have perceptions of
objects which affect them, and seem to have memory of them when they
are repeated. Yet they can vary their actions and change their
habits, though they do not possess the organ whose acts could give
them the means.

"_On the Instincts of Animals._

"We define instinct as the sum (_ensemble_) of the decisions
(_déterminations_) of animals in their actions; and, indeed, some
have thought that these determinations were the product of a
rational choice, and consequently the fruit of experience. Others,
says Cabanis, may think with the observers of all ages that several
of these decisions should not be ascribed to any kind of reasoning,
and that, without ceasing as for that to have their source in
physical sensibility, they are most often formed without the will of
the individuals able to have any other part than in better directing
the execution. It should be added, without the will having any part
in it; for when it does not act, it does not, of course, direct the
execution.

"If it had been considered that all the animals which enjoy the
power of sensation have their inner feeling susceptible of being
aroused by their needs, and that the movements of their nervous
fluids, which result from these emotions, are constantly directed by
this inner sentiment and by habits, then it has been felt that in
all the animals deprived of intelligence all the decisions of action
can never be the result of a rational choice, of judgment, of
profitable experience--in a word, of will--but that they are
subjected to needs which certain sensations excite, and which awaken
the inclinations which urge them on.

"In the animals even which enjoy the power of performing certain
intelligent acts, it is still more often the inner feeling and the
inclinations originating from habits which decide, without choice,
the acts which animals perform.

"Moreover, although the executing power of movements and of actions,
as also the cause which directs them, should be entirely internal,
it is not well, as has been done,[186] to limit to internal
impressions the primary cause or provocation of these acts, with the
intention to restrict to external impressions that which provokes
intelligent acts; for, from what few facts are known bearing on
these considerations, we are convinced that, either way, the causes
which arouse and provoke acts are sometimes internal and sometimes
external, that these same causes give rise in reality to impressions
all of which act internally.

"According to the idea generally attached to the word _instinct_ the
faculty which this word expresses is considered as a light which
illuminates and guides animals in their actions, and which is with
them what reason is to us. No one has shown that instinct can be a
force which calls into action; that this force acts effectively
without any participation of the will, and that it is constantly
directed by acquired inclinations."

There are, the author states, two kinds of causes which can arouse the inner feeling (organic sense)--namely, those which depend on intellectual acts, and those which, without arising from it, immediately excite it and force it to direct its power of acting in the direction of acquired inclinations.

"These are the only causes of this last kind, which constitute all
the acts of _instinct_; and as these acts are not the result of
deliberation, of choice, of judgment, the actions which arise from
them always satisfy, surely and without error, the wants felt and
the propensities arising from habits.

"Hence, _instinct_ in animals is an inclination which necessitates
that from sensations provoked while giving rise to wants the animal
is impelled to act without the participation of any thought or any
act of the will.

"This propensity owes to the organization what the habits have
modified in its favor, and it is excited by impressions and wants
which arouse the organic sense of the individual and put it in the
way of sending the nervous fluid in the direction which the
propensity in activity needs to the muscles to be placed in action.

"I have already said that the habit of exercising such an organ, or
such a part of the body, to satisfy the needs which often spring up,
should give to the subtile fluid which changes its place where is to
be operated the power which causes action so great a facility in
moving towards this organ, where it has been so often employed, that
this habit should in a way become inherent in the nature of the
individual, which is unable to change it.

"Moreover, the wants of animals possessing a nervous system being,
in each case, dependent on the Structure of these organisms, are:

"1. Of obtaining any kind of food;

"2. Of yielding to sexual fecundation which excites in them certain
sensations;

"3. Of avoiding pain;

"4. Of seeking pleasure or happiness.

"To satisfy these wants they contract different kinds of habits,
which are transformed into so many propensities, which they can
neither resist nor change. From this originate their habitual
actions, and their special propensities to which we give the name
of instinct.[187]

"This propensity of animals to preserve their habits and to renew
the actions resulting from them being once acquired, is then
propagated by means of reproduction or generation, which preserves
the organization and the disposition of parts in the state thus
attained, so that this same propensity already exists in the new
individuals even before they have exercised it.

"It is thus that the same habits and the same _instinct_ are
perpetuated from generation to generation in the different species
or races of animals, without offering any notable variation,[188] so
long as it does not suffer change in the circumstances essential to
the mode of life."

"_On the Industry of Certain Animals._

"In those animals which have no brain that which we call _industry_
as applied to certain of their actions does not deserve such a name,
for it is a mistake to attribute to them a faculty which they do not
possess.

"Propensities transmitted and received by heredity (_génération_);
habits of performing complicated actions, and which result from
these acquired propensities; finally, different difficulties
gradually and habitually overcome by as many emotions of the organic
sense (_sentiment intérieur_), constitute the sum of actions which
are always the same in the individuals of the same race, to which we
inconsiderately give the name of _industry_.

"The instinct of animals being formed by the habit of satisfying the
four kinds of wants mentioned above, and resulting from the
propensities acquired for a long time which urge them on in a way
determined for each species, there comes to pass, in the case of
some, only a complication in the actions which can satisfy these
four kinds of wants, or certain of them, and, indeed, only the
different difficulties necessary to be overcome have gradually
compelled the animal to extend and make contrivances, and have led
it, without choice or any intellectual act, but only by the emotions
of the organic sense, to perform such and such acts.

"Hence the origin, in certain animals, of different complicated
actions, which has been called _industry_, and which are so
enthusiastically admired, because it has always been supposed, at
least tacitly, that these actions were contrived and deliberately
planned, which is plainly erroneous. They are evidently the fruit of
a necessity which has expanded and directed the habits of the
animals performing them, and which renders them such as we observe.

"What I have just said is especially applicable to the invertebrate
animals, in which there enters no act of intelligence. None of
these can indeed freely vary its actions; none of them has the power
of abandoning what we call its _industry_ to adopt any other kind.

"There is, then, nothing wonderful in the supposed industry of the
ant-lion (_Myrmeleon formica-leo_), which, having thrown up a
hillock of movable sand, waits until its booty is thrown down to the
bottom of its funnel by the showers of sand to become its victim;
also there is none in the manoeuvre of the oyster, which, to
satisfy all its wants, does nothing but open and close its shell. So
long as their organization is not changed they will always, both of
them, do what we see them do, and they will do it neither
voluntarily nor rationally.

"This is not the case with the vertebrate animals, and it is among
them, especially in the birds and mammals, that we observe in their
actions traces of a true _industry_; because in difficult cases
their intelligence, in spite of their propensity to habits, can aid
them in varying their actions. These acts, however, are not common,
and are only slightly manifested in certain races which have
exercised them more, as we have had frequent occasion to remark."

Lamarck then (chapter vi.) examines into the nature of the _will_, which he says is really the principle underlying all the actions of animals. The will, he says, is one of the results of thought, the result of a reflux of a portion of the nervous fluid towards the parts which are to act.

He compares the brain to a register on which are imprinted ideas of all kinds acquired by the individual, so that this individual provokes at will an effusion of the nervous fluid on this register, and directs it to any particular page. The remainder of the second volume (chapter vii.) is devoted to the understanding, its origin and that of ideas. The following additions relative to chapters vii. and viii. of the first part of this work are from vol. ii., pp. 451-466.

In the last of June, 1809, the menagerie of the Museum of Natural History having received a Phoca (_Phoca vitulina_), Lamarck, as he says, had the opportunity of observing its movements and habits. After describing its habits in swimming and moving on land and observing its relation to the clawed mammals, he says his main object is to remark that the seals do not have the hind legs arranged in the same direction as the axis of their body, because these animals are constrained to habitually use them to form a caudal fin, closing and widening, by spreading their digits, the paddle (_palette_) which results from their union.

"The morses, on the contrary, which are accustomed to feed on grass
near the shore, never use their hind feet as a caudal fin; but their
feet are united together with the tail, and cannot separate. Thus in
animals of similar origin we see a new proof of the effect of habits
on the form and structure of organs."

He then turns to the flying mammals, such as the flying squirrel (_Sciurus volans_, _ærobates_, _petaurista_, _sagitta_, and _volucella_), and then explains the origin of their adaptation for flying leaps.

"These animals, more modern than the seals, having the habit of
extending their limbs while leaping to form a sort of _parachute_,
can _only_ make a very prolonged leap when they glide down from a
tree or spring only a short distance from one tree to another. Now,
by frequent repetitions of such leaps, in the individuals of these
races the skin of their sides is expanded on each side into a loose
membrane, which connects the hind and fore legs, and which,
enclosing a volume of air, prevents their sudden falling. These
animals are, moreover, without membranes between the fingers and
toes.

"The Galeopithecus (_Lemur volans_), undoubtedly a more ancient form
but with the same habits as the flying squirrel (_Pteromys Geoff._),
has the skin of the _flancs_ more ample, still more developed,
connecting not only the hinder with the fore legs, but in addition
the fingers and the tail with the hind feet. Moreover, they leap
much farther than the flying squirrels, and even make a sort of
flight.[189]

"Finally, the different bats are probably mammals still older than
the Galeopithecus, in the habit of extending their membrane and even
their fingers to encompass a greater volume of air, so as to sustain
their bodies when they fly out into the air.

"By these habits, for so long a period contracted and preserved, the
bats have obtained not only lateral membranes, but also an
extraordinary elongation of the fingers of their fore feet (with the
exception of the thumb), between which are these very ample
membranes uniting them; so that these membranes of the hands become
continuous with those of the flanks, and with those which connect
the tail with the two hind feet, forming in these animals great
membranous wings with which they fly perfectly, as everybody knows.

"Such is then the power of habits, which have a singular influence
on the conformation of parts, and which give to the animals which
have for a long time contracted certain of them, faculties not found
in other animals.

"As regards the amphibious animals of which I have often spoken, it
gives me pleasure to communicate to my readers the following
reflections which have arisen from an examination of all the objects
which I have taken into consideration in my studies, and seen more
and more to be confirmed.

"I do not doubt but that the mammals have in reality originated from
them, and that they are the veritable cradle (_berceau_) of the
entire animal kingdom.

"Indeed, we see that the least perfect animals (and they are the
most numerous) live only in the water; hence it is probable, as I
have said (vol. ii., p. 85), that it is only in the water or in very
humid places that nature causes and still forms, under favorable
conditions, direct or spontaneous generations which have produced
the simplest animalcules and those from which have successively been
derived all the other animals.

"We know that the Infusoria, the polyps, and the Radiata only live
in the water; that the worms even only live some in the water and
others in very damp places.

"Moreover, regarding the worms, which seem to form an initial branch
of the animal scale, since it is evident that the Infusoria form
another branch, we may suppose that among those of them which are
wholly aquatic--namely, which do not live in the bodies of other
animals, such as the Gordius and many others still unknown--there
are doubtless a great many different aquatic forms; and that among
these aquatic worms, those which afterwards habitually expose
themselves to the air have probably produced amphibious insects,
such as the mosquitoes, the ephemeras, etc., etc., which have
successively given origin to all the insects which live solely in
the air. But several races of these having changed their habits by
the force of circumstances, and having formed habits of a life
solitary, retired, or hidden, have given rise to the arachnides,
almost all of which also live in the air.

"Finally, those of the arachnides which have frequented the water,
which have consequently become progressively habituated to live in
it, and which finally cease to expose themselves to the air--this
indicates the relations which, connecting the Scolopendræ to Julus,
this to the Oniscus, and the last to Asellus, shrimps, etc., have
caused the existence of all the Crustacea.

"The other aquatic worms which are never exposed to the air,
multiplying and diversifying their races with time, and gradually
making progress in the complication of their structure, have caused
the formation of the Annelida, Cirripedia, and molluscs, which
together form an uninterrupted portion of the animal scale.

"In spite of the considerable hiatus which we observe between the
known molluscs and the fishes, the molluscs, whose origin I have
just indicated, have, by the intermediation of those yet remaining
unknown, given origin to the fishes, as it is evident that the
latter have given rise to the reptiles.

"In continuing to consult the probabilities on the origin of
different animals, we cannot doubt but that the reptiles, by two
distinct branches which circumstances have brought about, have given
rise on one side to the formation of birds, and on the other to
that of amphibious mammals, which have given in their turn origin to
all the other mammals.[190]

"Indeed, the fishes having caused the formation of Batrachia, and
these of the Ophidian reptiles, both having only one auricle in the
heart, nature has easily come to give a heart with a double auricle
to other reptiles which constitute two special branches; finally,
she has easily arrived at the end of forming, in the animals which
had originated from each of these branches, a heart with two
ventricles.

"Thus, among the reptiles whose heart has a double auricle, on the
one side, the Chelonians seem to have given origin to the birds; if,
independently of several relations which we cannot disregard, I
should place the head of a tortoise on the neck of certain birds, I
should perceive almost no disparity in the general physiognomy of
the factitious animal; and on the other side, the saurians,
especially the 'planicaudes,' such as the crocodiles, seem to have
given origin to the amphibious mammals.

"If the branch of the Chelonians has given rise to birds, we can yet
presume that the palmipede aquatic birds, especially the
_brevipennes_, such as the penguins and the _manchots_, have given
origin to the monotremes.

"Finally, if the branch of saurians has given rise to the amphibious
mammals, it will be most probable that this branch is the source
whence all the mammals have taken their origin.

"I therefore believe myself authorized to think that the terrestrial
mammals originally descended from those aquatic mammals that we call
Amphibia. Because the latter being divided into three branches by
the diversity of the habits which, with the lapse of time, they have
adopted, some have caused the formation of the Cetacea, others that
of the ungulated mammals, and still others that of the unguiculate
mammals.

"For example, those of the Amphibia which have preserved the habit
of frequenting the shores differ in the manner of taking their food.
Some among them accustoming themselves to browse on herbage, such as
the morses and lamatines, gradually gave origin to the ungulate
mammals, such as the pachyderms, ruminants, etc.; the others, such
as the Phocidæ, contracting the habit of feeding on fishes and
marine animals, caused the existence of the unguiculate mammals, by
means of races which, while becoming differentiated, became entirely
terrestrial.

"But those aquatic mammals which would form the habit of never
leaving the water, and only rising to breathe at the surface, would
probably give origin to the different known cetaceans. Moreover, the
ancient and complete habitation of the Cetacea in the ocean has so
modified their structure that it is now very difficult to recognize
the source whence they have derived their origin.

"Indeed, since the enormous length of time during which these
animals have lived in the depths of the sea, never using their hind
feet in seizing objects, their disused feet have wholly disappeared,
as also their skeleton, and even the pelvis serving as their
attachment.

"The alteration which the cetaceans have undergone in their limbs,
owing to the influence of the medium in which they live and the
habits which they have there contracted, manifests itself also in
their fore limbs, which, entirely enveloped by the skin, no longer
show externally the fingers in which they end; so that they only
offer on each side a fin which contains concealed within it the
skeleton of a hand.

"Assuredly, the cetaceans being mammals, it entered into the plan of
their structure to have four limbs like the others, and
consequently a pelvis to sustain their hind legs. But here, as
elsewhere, that which is lacking in them is the result of atrophy
brought about, at the end of a long time, by the want of use of the
parts which were useless.

"If we consider that in the Phocæ, where the pelvis still exists,
this pelvis is impoverished, narrowed, and with no projections on
the hips, we see that the lessened (_médiocre_) use of the hind feet
of these animals must be the cause, and that if this use should
entirely cease, the hind limbs and even the pelvis would in the end
disappear.

"The considerations which I have just presented may doubtless appear
as simple conjectures, because it is possible to establish them only
on direct and positive proofs. But if we pay any attention to the
observations which I have stated in this work, and if then we
examine carefully the animals which I have mentioned, as also the
result of their habits and their surroundings, we shall find that
these conjectures will acquire, after this examination, an eminent
probability.

"The following _tableau_[191] will facilitate the comprehension of
what I have just stated. It will be seen that, in my opinion, the
animal scale begins at least by two special branches, and that in
the course of its extent some branchlets (_rameaux_) would seem to
terminate in certain places.

"This series of animals beginning with two branches where are
situated the most imperfect, the first of these branches received
their existence only by direct or spontaneous generation.

"A strong reason prevents our knowing the changes successively
brought about which have produced the condition in which we observe
them; it is because we are never witnesses of these changes. Thus we
see the work when done, but never watching them during the process,
we are naturally led to believe that things have always been as we
see them, and not as they have progressively been brought about.

"Among the changes which nature everywhere incessantly produces in
her _ensemble_, and her laws remain always the same, such of these
changes as, to bring about, do not need much more time than the
duration of human life, are easily understood by the man who
observes them; but he cannot perceive those which are accomplished
at the end of a considerable time.

"If the duration of human life only extended to the length of a
_second_, and if there existed one of our actual clocks mounted and
in movement, each individual of our species who should look at the
hour-hand of this clock would never see it change its place in the
course of his life, although this hand would really not be
stationary. The observations of thirty generations would never learn
anything very evident as to the displacement of this hand, because
its movement, only being that made during half a minute, would be
too slight to make an impression; and if observations much more
ancient should show that this same hand had really moved, those who
should see the statement would not believe it, and would suppose
there was some error, each one having always seen the hand on the
same point of the dial-plate.

"I leave to my readers all the applications to be made regarding
this supposition.

"_Nature_, that immense totality of different beings and bodies, in
every part of which exists an eternal circle of movements and
changes regulated by law; totality alone unchangeable, so long as it
pleases its SUBLIME AUTHOR to make it exist, should be regarded as a
whole constituted by its parts, for a purpose which its Author alone
knows, and not exclusively for any one of them.

"Each part necessarily is obliged to change, and to cease to be one
in order to constitute another, with interests opposed to those of
all; and if it has the power of reasoning it finds this whole
imperfect. In reality, however, this whole is perfect, and
completely fulfils the end for which it was designed."

The last work in which Lamarck discussed the theory of descent was in his introduction to the _Animaux sans Vertèbres_. But here the only changes of importance are his four laws, which we translate, and a somewhat different phylogeny of the animal kingdom.

The four laws differ from the two given in the _Philosophie zoologique_ in his theory (the second law) accounting for the origin of a new organ, the result of a new need.

"_First law_: Life, by its proper forces, continually tends to
increase the volume of every body which possesses it, and to
increase the size of its parts, up to a limit which it brings about.

"_Second law_: The production of a new organ in an animal body
results from the supervention of a new want (_besoin_) which
continues to make itself felt, and of a new movement which this want
gives rise to and maintains.

"_Third law_: The development of organs and their power of action
are constantly in ratio to the employment of these organs.

"_Fourth law_: Everything which has been acquired, impressed upon,
or changed in the organization of individuals, during the course of
their life is preserved by generation and transmitted to the new
individuals which have descended from those which have undergone
those changes."

In explaining the second law he says:

"The foundation of this law derives its proof from the third, in
which the facts known allow of no doubt; for, if the forces of
action of an organ, by their increase, further develop this
organ--namely, increase its size and power, as is constantly proved
by facts--we may be assured that the forces by which it acts, just
originated by a new want felt, would necessarily give birth to the
organ adapted to satisfy this new want, if this organ had not before
existed.

"In truth, in animals so low as not to be able to _feel_, it cannot
be that we should attribute to a felt want the formation of a new
organ, this formation being in such a case the product of a
mechanical cause, as that of a new movement produced in a part of
the fluids of the animal.

"It is not the same in animals with a more complicated structure,
and which are able to _feel_. They feel wants, and each want felt,
exciting their inner feeling, forthwith sets the fluids in motion
and forces them towards the point of the body where an action may
satisfy the want experienced. Now, if there exists at this point an
organ suitable for this action, it is immediately cited to act; and
if the organ does not exist, and only the felt want be for instance
pressing and continuous, gradually the organ originates, and is
developed on account of the continuity and energy of its employment.