Chapter XVIII: Appendix: (p. 141)

_On Species in Living Bodies._

"I have for a long time thought that _species_ were constant in
nature, and that they were constituted by the individuals which
belong to each of them.

"I am now convinced that I was in error in this respect, and that in
reality only individuals exist in nature.

"The origin of this error, which I have shared with many naturalists
who still hold it, arises from _the long duration_, in relation to
us, _of the same state of things_ in each place which each organism
inhabits; but this duration of the same state of things for each
place has its limits, and with much time it makes changes in each
point of the surface of the globe, which produces changes in every
kind of circumstances for the organisms which inhabit it.

"Indeed, we may now be assured that nothing on the surface of the
terrestrial globe remains in the same state. Everything, after a
while, undergoes different changes, more or less prompt, according
to the nature of the objects and of circumstances. Elevated areas
are constantly being lowered, and the loose material carried down to
the lowlands. The beds of rivers, of streams, of even the sea, are
gradually removed and changed, as also the climate;[167] in a word,
the whole surface of the earth gradually undergoes a change in
situation, form, nature, and aspect. We see on every hand what
ascertained facts prove; it is only necessary to observe and to give
one's attention to be convinced of it.

"However, if, relatively to living beings, the diversity of
circumstances brings about for them a diversity of habits, a
different mode of existence, and, as the result, modifications in
their organs and in the shape of their parts, one should believe
that very gradually every living body whatever would vary in its
organization and its form.

"All the modifications that each living being will have undergone as
the result of change of circumstances which have influenced its
nature will doubtless be propagated by heredity (_génération_). But
as new modifications will necessarily continue to operate, however
slowly, not only will there continually be found new species, new
genera, and even new orders, but each species will vary in some part
of its structure and its form.

"I very well know that to our eyes there seems in this respect a
_stability_ which we believe to be constant, although it is not so
truly; for a very great number of centuries may form a period
insufficient for the changes of which I speak to be marked enough
for us to appreciate them. Thus we say that the flamingo
(_Phoenicopterus_) has always had as long legs and as long a neck
as have those with which we are familiar; finally, it is said that
all animals whose history has been transmitted for 2,000 or 3,000
years are always the same, and have lost or acquired nothing in the
process of perfection of their organs and in the form of their
different parts. We may be assured that this appearance of
_stability_ of things in nature will always be taken for reality by
the average of mankind, because in general it judges everything only
relatively to itself.

"But, I repeat, this consideration which has given rise to the
admitted error owes its source to the very great slowness of the
changes which have gone on. A little attention given to the facts
which I am about to cite will afford the strongest proof of my
assertion.

"What nature does after a great length of time we do every day by
suddenly changing, as regards a living being, the circumstances in
which it and all the individuals of its species are placed.

"All botanists know that the plants which they transplant from their
natal spot into gardens for cultivation there gradually undergo
changes which in the end render them unrecognizable. Many plants
naturally very hairy, there become glabrous or nearly so; a quantity
of those which were procumbent or trailing there have erect stems;
others lose their spines or their thorns; finally, the dimensions of
parts undergo changes which the circumstances of their new situation
infallibly produce. This is so well known that botanists prefer not
to describe them, at least unless they are newly cultivated. Is not
wheat (_Triticum sativum_) a plant brought by man to the state
wherein we actually see it, which otherwise I could not believe? Who
can now say in what place its like lives in nature?

"To these known facts I will add others still more remarkable, and
which confirm the view that change of circumstances operates to
change the parts of living organisms.

"When _Ranunculus aquatilis_ lives in deep water, all it can do
while growing is to make the end of its stalks reach the surface of
the water where they flourish. Then all the leaves of the plant are
finely cut or pinked.[168] If the same plant grows in shallower
water the growth of its stalks may give them sufficient extent for
the upper leaves to develop out of the water; then its lower leaves
only will be divided into hair-like joints, while the upper ones
will be simple, rounded, and a little lobed.[169] This is not all:
when the seeds of the same plant fall into some ditch where there is
only water or moisture sufficient to make them germinate, the plant
develops all its leaves in the air, and then none of them is divided
into capillary points, which gives rise to _Ranunculus hederaceus_,
which botanists regard as a species.

"Another very striking proof of the effect of a change of
circumstances on a plant submitted to it is the following:

"It is observed that when a tuft of _Juncus bufonius_ grows very
near the edge of the water in a ditch or marsh this rush then pushes
out filiform stems which lie in the water, are there deformed,
becoming disturbed (_traçantes_), proliferous, and very different
from that of _Juncus bufonius_ which grows out of water. This plant,
modified by the circumstances I have just indicated, has been
regarded as a distinct species; it is the _Juncus supinus_ of
Rotte.[170]

"I could also give citations to prove that the changes of
circumstances relative to organisms necessarily change the
influences which they undergo on the part of all that which environs
them or which acts on them, and so necessarily bring about changes
in their size, their shape, their different organs.

"Then among living beings nature seems to me to offer in an absolute
manner only individuals which succeed one another by generation.

"However, in order to facilitate the study and recognition of these
organisms, I give the name of _species_ to every collection of
individuals which during a long period resemble each other so much
in all their parts that these individuals only present small
accidental differences which, in plants, reproduction by seeds
causes to disappear.

"But, besides that at the end of a long period the totality of
individuals of such a species change as the circumstances which act
on them, those of these individuals which from special causes are
transported into very different situations from those where the
others occur, and then constantly submitted to other influences--the
former, I say, assume new forms as the result of a long habit of
this other mode of existence, and then they constitute a new
_species_, which comprehends all the individuals which occur in the
same condition of existence. We see, then, the faithful picture of
that which happened in this respect in nature, and of that which the
observation of its acts can alone discover to us."

III. _Lamarck's Views on Species, as published in 1803._

In the opening lecture[171] of his course at the Museum of Natural History, delivered in prairial (May 20-June 18), 1803, we have a further statement of the theoretical views of Lamarck on species and their origin. He addresses his audience as "Citoyens," France still being under the _régime_ of the Republic.

The brochure containing this address is exceedingly rare, the only copy existing, as far as we know, being in the library of the Museum of Natural History in Paris. The author's name is not even given, and there is no imprint. Lamarck's name, however, is written on the outside of the cover of the copy we have translated. At the end of the otherwise blank page succeeding the last page (p. 46) is printed the words: _Esquisse d'un Philosophie zoologique_, the preliminary sketch, however, never having been added.

He begins by telling his hearers that they should not desire to burden their memories with the infinite details and immense nomenclature of the prodigious quantity of animals among which we distinguish an illimitable number of species, "but what is more worthy of you, and of more educational value, you should seek to know the course of nature." "You may enter upon the study of classes, orders, genera, and even of the most interesting species, because this would be useful to you; but you should never forget that all these subdivisions, which could not, however, be well spared, are artificial, and that nature does not recognize any of them."

"In the opening lecture of my last year's course I tried to convince
you that it is only in the organization of animals that we find the
foundation of the natural relations between the different groups,
where they diverge and where they approach each other. Finally, I
tried to show you that the enormous series of animals which nature
has produced presents, from that of its extremities where are placed
the most perfect animals, down to that which comprises the most
imperfect, or the most simple, an evident modification, though
irregularly defined (_nuancé_), in the structure of the
organization.

"To-day, after having recalled some of the essential considerations
which form the base of this great truth; after having shown you the
principal means by which nature is enabled to create (_opérer_) her
innumerable productions and to vary them infinitely; finally, after
having made you see that in the use she has made of her power of
generating and multiplying living beings she has necessarily
proceeded from the more simple to the more complex, gradually
complicating the organization of these bodies, as also the
composition of their substance, while also in that which she has
done on non-living bodies she has occupied herself unremittingly in
the destruction of all preëxistent combinations, I shall undertake
to examine under your eyes the great question in natural
history--What is a _species_ among organized beings?

"When we consider the series of animals, beginning at the end
comprising the most perfect and complicated, and passing down
through all the degrees of this series to the other end, we see a
very evident modification in structure and faculties. On the
contrary, if we begin with the end which comprises animals the most
simple in organization, the poorest in faculties and in organs--in a
word, the most imperfect in all respects--we necessarily remark, as
we gradually ascend in the series, a truly progressive complication
in the organization of these different animals, and we see the
organs and faculties of these beings successively multiplying and
diversifying in a most remarkable manner.

"These facts once known present truths which are, to some extent,
eternal; for nothing here is the product of our imagination or of
our arbitrary principles; that which I have just explained rests
neither on systems nor on any hypothesis: it is only the very simple
result of the observation of nature; hence I do not fear to advance
the view that all that one can imagine, from any motives whatever,
to contradict these great verities will always be destroyed by the
evidence of the facts with which it deals.

"To these facts it is necessary to add these very important
considerations, which observation has led me to perceive, and the
basis of which will always be recognized by those who pay attention
to them; they are as follows:

"Firstly, the exercise of life, and consequently of organic
movement, constitutes its activity, tends, without ceasing, not only
to develop and to extend the organization, but it tends besides to
multiply the organs and to isolate them in special centres
(_foyers_). To make sure whether the exercise of life tends to
extend and develop the organization, it suffices to consider the
state of the organs of any animal which has just been born, and to
compare them in this condition with what they are when the animal
has attained the period when its organs cease to receive any new
development. Then we will see on what this organic law is based,
which I have published in my _Recherches sur les Corps vivans_
(p. 8), _i.e._, that--

"'The special property of movement of fluids in the supple parts of
the living body which contain them is to open (_frayer_) there
routes, places of deposit and tissues; to create there canals, and
consequently different organs; to cause these canals and these
organs to vary there by reason of the diversity both of the
movements as well as the nature of the fluids which occur there;
finally to enlarge, to elongate, to divide and to gradually
strengthen (_affermir_) these canals and their organs by the matters
which are formed in the fluids in motion, which incessantly separate
themselves, and a part of which is assimilated and united with
organs while the rest is rejected.'

"Secondly, the continual employment of an organ, especially if it is
strongly exercised, strengthens this organ, develops it, increases
its dimensions, enlarges and extends its faculties.

"This second law of effects of exercise of life has been understood
for a long time by those observers who have paid attention to the
phenomena of organization.

"Indeed, we know that all the time that an organ, or a system of
organs, is rigorously exercised throughout a long time, not only its
power, and the parts which form it, grow and strengthen themselves,
but there are proofs that this organ, or system of organs, at that
time attracts to itself the principal active forces of the life of
the individual, because it becomes the cause which, under these
conditions, makes the functions of other organs to be diminished in
power.

"Thus not only every organ or every part of the body, whether of man
or of animals, being for a long period and more vigorously exercised
than the others, has acquired a power and facility of action that
the same organ could not have had before, and that it has never had
in individuals which have exercised less, but also we consequently
remark that the excessive employment of this organ diminishes the
functions of the others and proportionately enfeebles them.

"The man who habitually and vigorously exercises the organ of his
intelligence develops and acquires a great facility of attention, of
aptitude for thought, etc., but he has a feeble stomach and strongly
limited muscular powers. He, on the contrary, who thinks little does
not easily, and then only momentarily fixes his attention, while
habitually giving much exercise to his muscular organs, has much
vigor, possesses an excellent digestion, and is not given to the
abstemiousness of the savant and man of letters.

"Moreover, when one exercises long and vigorously an organ or system
of organs, the active forces of life (in my opinion, the nervous
fluid) have taken such a habit of acting (_porter_) towards this
organ that they have formed in the individual an inclination to
continue to exercise which it is difficult for it to overcome.

"Hence it happens that the more we exercise an organ, the more we
use it with facility, the more does it result that we perceive the
need (_besoin_) of continuing to use it at the times when it is
placed in action. So we remark that the habit of study, of
application, of work, or of any other exercise of our organs or of
any one of our organs, becomes with time an indispensable need to
the individual, and often a passion which it does not know how to
overcome.

"Thirdly, finally, the effort made by necessity to obtain new
faculties is aided by the concurrence of favorable circumstances;
they create (_créent_) with time the new organs which are adapted
(_propres_) to their faculties, and which as the result develop
after long use (_qu'en suite un long emploi développe_).

"How important is this consideration, and what light it spreads on
the state of organization of the different animals now living!

"Assuredly it will not be those who have long been in the habit of
observing nature, and who have followed attentively that which
happens to living individuals (to animals and to plants), who will
deny that a great change in the circumstances of their situation and
of their means of existence forces them and their race to adopt new
habits; it will not be those, I say, who attempt to contest the
foundation of the consideration which I have just exposed.

"They can readily convince themselves of the solidity of that which
I have already published in this respect.[172]

"I have felt obliged to recall to you these great considerations, a
sketch of which I traced for you last year, and which I have stated
for the most part in my different works, because they serve, as you
have seen, as a solution of the problem which interests so many
naturalists, and which concerns the determination of _species_ among
living bodies.

"Indeed, if in ascending in the series of animals from the most
simply organized animalcule, as from the monad, which seems to be
only an animated point, up to the animals the most perfect, or whose
structure is the most complicated--in a word, up to animals with
mammæ--you observe in the different orders which comprise this great
series a gradation, shaded (_nuancé_), although irregular, in the
composition of the organization and in the increasing number of
faculties, is it not evident that in the case where nature would
exert some active power on the existence of these organized bodies
she has been able to make them exist only by beginning with the most
simple, and that she has been able to form directly among the
animals only that which I call the rough sketches or germs
(_ébauches_) of animality--that is to say, only these animalcules,
almost invisible and to some extent without consistence, that we see
develop spontaneously and in an astonishing abundance in certain
places and under certain circumstances, while only in contrary
circumstances are they totally destroyed?

"Do we not therefore perceive that by the action of the laws of
organization, which I have just now indicated, and by that of
different means of multiplication which are due to them (_qui en
dérivent_), nature has in favorable times, places, and climates
multiplied her first germs (_ébauches_) of animality, given place to
developments of their organizations, rendered gradually greater the
duration of those which have originally descended from them, and
increased and diversified their organs? Then always preserving the
progress acquired by the reproductions of individuals and the
succession of generations, and aided by much time and by a slow but
constant diversity of circumstances, she has gradually brought about
in this respect the state of things which we now observe.

"How grand is this consideration, and especially how remote is it
from all that is generally thought on this subject! Moreover, the
astonishment which its novelty and its singularity may excite in you
requires that at first you should suspend your judgment in regard to
it. But the observation which establishes it is now on record
(_consignée_), and the facts which support it exist and are
incessantly renewed; however, as they open a vast field to your
studies and to your own researches, it is to you yourselves that I
appeal to pronounce on this great subject when you have sufficiently
examined and followed all the facts which relate to it.

"If among living bodies there are any the consideration of whose
organization and of the phenomena which they produce can enlighten
us as to the power of nature and its course relatively to the
existence of these bodies, also as to the variations which they
undergo, we certainly have to seek for them in the lowest classes of
the two organic kingdoms (the animals and the plants). It is in the
classes which comprise the living bodies whose organization is the
least complex that we can observe and bring together facts the most
luminous, observations the most decisive on the origin of these
bodies, on their reproduction and their admirable diversification,
finally on the formation and the development of their different
organs, the whole process being aided by the concurrence of
generations, of time, and of circumstances.

"It is, indeed, among living bodies the most multiplied, the most
numerous in nature, the most prompt and easy to regenerate
themselves, that we should seek the most instructive facts bearing
on the course of nature and on the means she has employed to create
her innumerable productions. In this case we perceive that,
relatively to the animal kingdom, we should chiefly give our
attention to the invertebrate animals, because their enormous
multiplicity in nature, the singular diversity of their systems of
organization and of their means of multiplication, their increasing
simplification, and the extreme fugacity of those which compose the
lowest orders of these animals, show us much better than the others
the true course of nature, and the means which she has used and
which she is still incessantly employing to give existence to all
the living bodies of which we have knowledge.

"Her course and her means are without doubt the same for the
production of the different plants which exist. And, indeed, though
it is not believed, as some naturalists have wrongly held, but
without proof, that plants are bodies more simple in organization
than the most simple animals, it is a veritable error which
observation plainly denies.

"Truly, vegetable substance is less surcharged with constituent
principles than any animal substance whatever, or at least most of
them, but the substance of a living body and the organization of
these bodies are two very different things. But there is in plants,
as in animals, a true gradation in organization from the plant
simplest in organization and parts up to plants the most complex in
structure and with the most diversified organs.

"If there is some approach, or at least some comparison to make
between vegetables and animals, this can only be by opposing plants
the most simply organized, like fungi and algæ, to the most
imperfect animals like the polyps, and especially the amorphous
polyps, which occur in the lowest order.

"At present we clearly see that in order to bring about the
existence of animals of all the classes, of all the orders, and of
all the genera, nature has had to begin by giving existence to those
which are the most simple in organization and lacking most in organs
and faculties, the frailest in constituency, the most ephemeral, the
quickest and easiest to multiply; and we shall find in the
_amorphous_ or _microscopic polyps_ the most striking examples of
this simplification of organization, and the indication that it is
solely among them that occur the astonishing germs of animality.

"At present we only know the principal law of the organization, the
power of the exercise of the functions of life, the influence of the
movement of fluids in the supple parts of organic bodies, and the
power which the regenerations have of conserving the progress
acquired in the composition of organs.

"At present, finally, relying on numerous observations, seeing that
with the aid of much time, of changes in local circumstances, in
climates, and consequently in the habits of animals, the progression
in the complication of their organization and in the diversity of
their parts has gradually operated (_a dû s'opérer_) in a way that
all the animals now known have been successively formed such as we
now see them, it becomes possible to find the solution of the
following question:

"What is a _species_ among living beings?

"All those who have much to do with the study of natural history
know that naturalists at the present day are extremely embarrassed
in defining what they mean by the word species.

"In truth, observation for a long time has shown us, and shows us
still in a great number of cases, collections of individuals which
resemble each other so much in their organization and by the
_ensemble_ of their parts that we do not hesitate to regard these
collections of similar individuals as constituting so many species.

"From this consideration we call _species_ every collection of
individuals which are alike or almost so, and we remark that the
regeneration of these individuals conserves the species and
propagates it in continuing successively to reproduce similar
individuals.

"Formerly it was supposed that each species was immutable, as old as
nature, and that she had caused its special creation by the Supreme
Author of all which exists.

"But we can impose on him laws in the execution of his will, and
determine the mode which he has been pleased to follow in this
respect, so it is only in this way that he permits us to recognize
it by the aid of observation. Has not his infinite power created an
order of things which successively gives existence to all that we
see as well as to all that which exists and which we do not know?

"Assuredly, whatever has been his will, the omnipotence of his power
is always the same; and in whatever way this supreme will has been
manifested, nothing can diminish its greatness. As regards, then,
the decrees of this infinite wisdom, I confine myself to the limits
of a simple observer of nature. Then, if I discover anything in the
course that nature follows in her creations, I shall say, without
fear of deceiving myself, that it has pleased its author that she
possesses this power.

"The idea that was held as to species among living bodies was quite
simple, easy to grasp, and seemed confirmed by the constancy in the
similar form of the individuals which reproduction or generation
perpetuated. There still occur among us a very great number of these
pretended species which we see every day.

"However, the farther we advance in the knowledge of the different
organized bodies with which almost every part of the surface of the
globe is covered, the more does our embarrassment increase in
determining what should be regarded as species, and the greater is
the reason for limiting and distinguishing the genera.

"As we gradually gather the productions of nature, as our
collections gradually grow richer, we see almost all the gaps filled
up, and our lines of demarcation effaced. We find ourselves
compelled to make an arbitrary determination, which sometimes leads
us to seize upon the slightest differences between varieties to form
of them the character of that which we call species, and sometimes
one person designates as a variety of such a species individuals a
little different, which others regard as constituting a particular
species.

"I repeat, the richer our collections become, the more numerous are
the proofs that all is more or less shaded (_nuancé_), that the
remarkable differences become obliterated, and that the more often
nature leaves it at our disposal to establish distinctions only
minute, and in some degree trivial peculiarities.

"But some genera among animals and plants are of such an extent,
from the number of species they contain, that the study and the
determination of these species are now almost impossible. The
species of these genera, arranged in series and placed together
according to their natural relations, present, with those allied to
them, differences so slight that they shade into each other; and
because these species are in some degree confounded with one another
they leave almost no means of determining, by expression in words,
the small differences which distinguish them.

"There are also those who have been for a long time, and strongly,
occupied with the determination of the species, and who have
consulted rich collections, who can understand up to what point
species, among living bodies, merge one into another (_fondent les
unes dans les autres_), and who have been able to convince
themselves, in the regions (_parties_) where we see isolated
species, that this is only because there are wanting other species
which are more nearly related, and which we have not yet collected.

"I do not mean to say by this that the existing animals form a very
simple series, one everywhere equally graduated; but I say that they
form a branching series, irregularly graduated, and which has no
discontinuity in its parts, or which at best has not always had, if
it is true that it is to be found anywhere (_s'il est vrai qu'il
s'en trouve quelque part_). It results from this that the species
which terminates each branch of the general series holds a place at
least on one side apart from the other allied species which
intergrade with them. Behold this state of things, so well known,
which I am now compelled to demonstrate.

"I have no need (_besoin_) of any hypothesis or any supposition for
this: I call to witness all observing naturalists.

"Not only many genera, but entire orders, and some classes even,
already present us with portions almost complete of the state of
things which I have just indicated.

"However, when in this case we have arranged the species in series,
and they are all well placed according to their natural relations,
if you select one of them, and it results in making a leap (_saut
pardessus_) over to several others, you take another one of them a
little less remote; these two species, placed in comparison, will
then present the greatest differences from each other. It is thus
that we had begun to regard most of the productions of nature which
occur at our door. Then the generic and specific distinctions were
very easy to establish. But now that our collections are very much
richer, if you follow the series that I have cited above, from the
species that you first chose up to that which you took in the second
place, and which is very different from the first, you have passed
from shade to shade without having remarked any differences worth
noticing.

"I ask what experienced zoölogist or botanist is there who has not
thoroughly realized that which I have just explained to you?

"Or how can one study, or how can one be able to determine in a
thorough way the species, among the multitude of known polyps of all
orders of radiates, worms, and especially of insects, where the
simple genera of Papilio, Phalæna, Noctua, Tinea, Musca, Ichneumon,
Curculio, Capricorn, Scarabæus, Cetonia, etc., etc., already contain
so many closely allied species which shade into each other, are
almost confounded one with another? What a host of molluscan shells
exist in every country and in all seas which elude our means of
distinction, and exhaust our resources in this respect! Ascend to
the fishes, to the reptiles, to the birds, even to the mammals, and
you will see, except the lacunæ which are still to be filled,
everywhere shadings which take place between allied species, even
the genera, and where after the most industrious study we fail to
establish good distinctions. Does not botany, which considers the
other series, comprising the plants, offer us, in its different
parts, a state of things perfectly similar? In short, what
difficulties do not arise in the study and in the determination of
species in the genera Lichena, Fucus, Carex, Poa, Piper, Euphorbia,
Erica, Hieracium, Solanum, Geranium, Mimosa, etc., etc.?

"When these genera were established but a small number of species
were known, and then it was easy to distinguish them; but at present
almost all the gaps between them are filled, and our specific
differences are necessarily minute and very often insufficient.

"From this state of things well established we see what are the
causes which have given rise to them; we see whether nature
possesses the means for this, and if observation has been able to
give us our explanation of it.

"A great many facts teach us that gradually as the individuals of
one of our species change their situation, climate, mode of life, or
habits, they thus receive influences which gradually change the
consistence and the proportions of their parts, their form, their
faculties, even their organization; so that all of them participate
eventually in the changes which they have undergone.

"In the same climate, very different situations and exposures at
first cause simple variations in the individuals which are found
exposed there; but, as time goes on, the continual differences of
situation of individuals of which I have spoken, which live and
successively reproduce in the same circumstances, give rise among
them to differences which are, in some degree, essential to their
being, in such a way that at the end of many successive generations
these individuals, which originally belonged to another species, are
at the end transformed into a new species, distinct from the other.

"For example, if the seeds of a grass, or of every other plant
natural to a humid field, should be transplanted, by an accident, at
first to the slope of a neighboring hill, where the soil, although
more elevated, would yet be quite cool (_frais_) so as to allow the
plant to live, and then after having lived there, and passed through
many generations there, it should gradually reach the poor and
almost arid soil of a mountain side--if the plant should thrive and
live there and perpetuate itself during a series of generations, it
would then be so changed that the botanists who should find it there
would describe it as a separate species.

"The same thing happens to animals which circumstances have forced
to change their climate, manner of living, and habits; but for these
the influences of the causes which I have just cited need still more
time than in the case of plants to produce the notable changes in
the individuals, though in the long run, however, they always
succeed in bringing them about.

"The idea of defining under the word _species_ a collection of
similar individuals which perpetuate the same by generation, and
which have existed thus as anciently as nature, implies the
necessity that the individuals of one and the same species cannot
mix, in their acts of generation, with the individuals of a
different species. Unfortunately observation has proved, and still
proves every day, that this consideration has no basis; for the
hybrids, very common among plants, and the unions which are often
observed between the individuals of very different species among
animals, have made us perceive that the limits between these
species, supposed to be constant, are not so rigid as is supposed.

"In truth, nothing often results from these singular unions,
especially when they are very incongruous, as the individuals which
result from them are usually sterile; but also, when the disparities
are less great, it is known that the drawbacks (_défauts_) with
which it has to do no longer exist. However, this means alone
suffices to gradually create the varieties which have afterwards
arisen from races, and which, with time, constitute that which we
call _species_.

"To judge whether the idea which is formed of species has any real
foundation, let us return to the considerations which I have already
stated; they are, namely--

"1. That all the organic bodies of our globe are veritable
productions of nature, which she has created in succession at the
end of much time.

"2. That in her course nature has begun, and begins anew every day,
by forming the simplest organic bodies, and that she directly forms
only these--that is to say, only these first primitive germs
(_ébauches_) of organization, which have been badly characterized by
the expression of "spontaneous generations" (_qu'on a désignées
mal-à-propos par l'expression de Générations spontanées_).

"3. That the first germs (_ébauches_) of the animals and plants were
formed in favorable places and circumstances. The functions of life
beginning and an organic movement established, these have
necessarily gradually developed the organs, so that after a time and
under suitable circumstances they have been differentiated, as also
the different parts (_elles les ont diversifiés ainsi qui les
parties_).

"4. That the power of increase in each portion of organic bodies
being inherited at the first production (_effets_) of life, it has
given rise to different modes of multiplication and of regeneration
of individuals; and in that way the progress acquired in the
composition of the organization and in the forms and the diversity
of the parts has been preserved.

"5. That with the aid of sufficient time, of circumstances which
have been necessarily favorable, of changes that all parts of the
surface of the globe have successively undergone in their
condition--in a word, with the power that new situations and new
habits have in modifying the organs of bodies endowed with life--all
those which now exist have been imperceptibly formed such as we see
them.

"6. Finally, that according to a similar order of things, living
beings, having undergone each of the more or less great changes in
the condition of their organization and of their parts, that which
is designated as a species among them has been insensibly and
successively so formed, can have only a relative constancy in its
condition, and cannot be as ancient as nature.

"But, it will be said, when it is necessary to suppose that, with
the aid of much time and of an infinite variation in circumstances,
nature has gradually formed the different animals that we know,
would we not be stopped in this supposition by the sole
consideration of the admirable diversity which we observe in the
instinct of different animals, and by that of the marvels of all
sorts which their different kinds of industry present?

"Will one dare to carry the spirit of system (_porter l'esprit de
système_) to the point of saying that it is nature, and she alone,
which creates this astonishing diversity of means, of ruses, of
skill, of precautions, of patience, of which the industry of animals
offers us so many examples! What we observe in this respect in the
class of insects alone, is it not a thousand times more than is
necessary to compel us to perceive that the limits of the power of
nature by no means permit her herself to produce so many marvels,
and to force the most obstinate philosophy to recognize that here
the will of the supreme author of all things has been necessary, and
has alone sufficed to cause the existence of so many admirable
things?

"Without doubt one would be rash, or rather wholly unreasonable, to
pretend to assign limits to the power of the first author of all
things; and by that alone no one can dare to say that this infinite
power has not been able to will that which nature herself shows us
she has willed.

"This being so, if I discover that nature herself brings about or
causes all the wonders just cited; that she creates the
organization, the life, even feeling; that she multiplies and
diversifies, within limits which are not known to us, the organs and
faculties of organic bodies the existence of which she sustains or
propagates; that she has created in animals by the single way of
_need_, which establishes and directs the habits, the source of all
actions, from the most simple up to those which constitute
_instinct_, industry, finally reason, should I not recognize in this
power of nature--that is to say, of existing things--the execution
of the will of its sublime author, who has been able to will that it
should have this power? Shall I any the less wonder at the
omnipotence of the power of the first cause of all things, if it has
pleased itself that things should be thus, than if by so many
(separate) acts of his omnipotent will he should be occupied and
occupy himself still continually with details of all the special
creations, all the variations, and all the developments and
perfections, all the destructions and all the renewals--in a word,
with all the changes which are in general produced in things which
exist?

"But I intend to prove in my 'Biologie' that nature possesses in her
_faculties_ all that is necessary to have to be able herself to
produce that which we admire in her works; and regarding this
subject I shall then enter into sufficient details which I am here
obliged to omit.[173]

"However, it is still objected that all we see stated regarding the
state of living bodies are unalterable conditions in the
preservation of their form, and it is thought that all the animals
whom history has transmitted to us for two or three thousand years
have always remained the same, and have lost nothing nor acquired
anything in the perfecting of their organs and in the form of their
parts.

"While this apparent stability has for a long time been accepted as
true, it has just been attempted to establish special proofs in a
report on the collections of natural history brought from Egypt by
the citizen Geoffroy."

Quotes three paragraphs in which the reporters (Cuvier and Geoffroy St. Hilaire) say that the mummied animals of Thebes and Memphis are perfectly similar to those of to-day. Then he goes on to say:

"I have seen them, these animals, and I believe in the conformity of
their resemblance with the individuals of the same species which
live to-day. Thus the animals which the Egyptians worshipped and
embalmed two or three thousand years ago are still in every respect
similar to those which actually live in that country.

"But it would be assuredly very singular that this should be
otherwise; for the position of Egypt and its climate are still or
very nearly the same as at former times. Therefore the animals which
live there have not been compelled to change their habits.

"There is, then, nothing in the observation which has just been
reported which should be contrary to the considerations which I
have expressed on this subject; and which especially proves that the
animals of which it treats have existed during the whole period of
nature. It only proves that they have existed for two or three
thousand years; and every one who is accustomed to reflect, and at
the same time to observe that which nature shows us of the monuments
of its antiquity, readily appreciates the value of a duration of two
or three thousand years in comparison with it.

"Hence, as I have elsewhere said, it is sure that this appearance of
the stability of things in nature will always be mistaken by the
average of mankind for the reality; because in general people only
judge of everything relatively to themselves.

"For the man who observes, and who in this respect only judges from
the changes which he himself perceives, the intervals of these
changes are _stationary conditions_ (_états_) which should appear to
be limitless, because of the brevity of life of the individuals of
his species. Thus, as the records of his observations and the notes
of facts which he has consigned to his registers only extend and
mount up to several thousands of years (three to five thousand
years), which is an infinitely small period of time relatively to
those which have sufficed to bring about the great changes which the
surface of the globe has undergone, everything seems _stable_ to him
in the planet which he inhabits, and he is inclined to reject the
monuments heaped up around him or buried in the earth which he
treads under his feet, and which surrounds him on all sides.[174]

* * * * *

"It seems to me [as mistaken as] to expect some small creatures
which only live a year, which inhabit some corner of a building,
and which we may suppose are occupied with consulting among
themselves as to the tradition, to pronounce on the duration of the
edifice where they occur: and that going back in their paltry
history to the twenty-fifth generation, they should unanimously
decide that the building which serves to shelter them is eternal, or
at least that it has always existed; because it has always appeared
the same to them; and since they have never heard it said that it
had a beginning. Great things (_grandeurs_) in extent and in
duration are relative.[175]

"When man wishes to clearly represent this truth he will be reserved
in his decisions in regard to stability, which he attributes in
nature to the state of things which he observes there.[176]

"To admit the insensible change of species, and the modifications
which individuals undergo as they are gradually forced to vary their
habits or to contract new ones, we are not reduced to the unique
consideration of too small spaces of time which our observations can
embrace to permit us to perceive these changes; for, besides this
induction, a quantity of facts collected for many years throws
sufficient light on the question that I examine, so that does not
remain undecided; and I can say now that our sciences of observation
are too advanced not to have the solution sought for made evident.

"Indeed, besides what we know of the influences and the results of
heteroclite fecundations, we know positively to-day that a forced
and long-sustained change, both in the habits and mode of life of
animals, and in the situation, soil, and climate of plants, brings
about, after a sufficient time has elapsed, a very remarkable change
in the individuals which are exposed to them.

"The animal which lives a free, wandering life on plains, where it
habitually exercises itself in running swiftly; the birds whose
needs (_besoins_) require them unceasingly to traverse great spaces
in the air, finding themselves enclosed, some in the compartments of
our menageries or in our stables, and others in our cages or in our
poultry yards, are submitted there in time to striking influences,
especially after a series of regenerations under the conditions
which have made them contract new habits. The first loses in large
part its nimbleness, its agility; its body becomes stouter, its
limbs diminish in power and suppleness, and its faculties are no
longer the same. The second become clumsy; they are unable to fly,
and grow more fleshy in all parts of their bodies.

"Behold in our stout and clumsy horses, habituated to draw heavy
loads, and which constitute a special race by always being kept
together--behold, I say, the difference in their form compared with
those of English horses, which are all slender, with long necks,
because for a long period they have been trained to run swiftly:
behold in them the influence of a difference of habit, and judge for
yourselves. You find them, then, such as they are in some degree in
nature. You find there our cock and our hen in the condition we have
[made] them, as also the mixed races that we have formed by mixed
breeding between the varieties produced in different countries, or
where they were so in the state of domesticity. You find there
likewise our different races of domestic pigeons, our different
dogs, etc. What are our cultivated fruits, our wheat, our cabbage,
our lettuce, etc., etc., if they are not the result of changes which
we ourselves have effected in these plants, in changing by our
culture the conditions of their situation? Are they now found in
this condition in nature? To these incontestable facts add the
considerations which I have discussed in my _Recherches sur les
Corps vivans_ (p. 56 _et suiv._), and decide for yourselves.

"Thus, among living bodies, nature, as I have already said, offers
only in an absolute way individuals which succeed each other
genetically, and which descend one from the other. So the _species_
among them are only relative, and only temporary.

"Nevertheless, to facilitate the study and the knowledge of so many
different bodies it is useful to give the name of _species_ to the
entire collection of individuals which are alike, which reproduction
perpetuates in the same condition as long as the conditions of their
situation do not change enough to make their habits, their
character, and their form vary.

"Such is, citizens, the exact sketch of that which goes on in nature
since she has existed, and of that which the observation of her acts
has alone enabled us to discover. I have fulfilled my object if, in
presenting to you the results of my researches and of my experience,
I have been able to disclose to you that which in your studies of
this kind deserves your special attention.

"You now doubtless conceive how important are the considerations
which I have just exposed to you, and how wrong you would be if, in
devoting yourself to the study of animals or of plants, you should
seek to see among them only the multiplied distinctions that we have
been obliged to establish; in a word, if you should confine
yourselves to fixing in your memory the variable and indefinite
nomenclature which is applied to so many different bodies, instead
of studying Nature herself--her course, her means, and the constant
results that she knows how to attain."

On the next fly page are the following words: _Esquisse d'une Philosophie zoologique_.

IV. _Lamarck's Views as published in 1806._[177]

"Those who have observed much and have consulted the great
collections, have been able to convince themselves that as gradually
as the circumstances of their habitat, of exposure to their
surroundings, of climate, food, mode of living, etc., have changed,
the characters of size, form, of proportion between the parts, of
color, of consistence, of duration, of agility, and of industry have
proportionately changed.

"They have been able to see, as regards the animals, that the more
frequent and longer sustained use of any organ gradually strengthens
this organ, develops it, enlarges it, and gives it a power
proportional to the length of time it has been used; while the
constant lack of use of such an organ insensibly weakens it, causes
it to deteriorate, progressively diminishes its faculties, and tends
to make it waste away.[178]

"Finally, it has been remarked that all that nature has made
individuals to acquire or lose by the sustained influence of
circumstances where their race has existed for a long time, she has
preserved by heredity in the new individuals which have originated
from them (_elle le conserve par la génération aux nouveaux
individus qui en proviennent_). These verities are firmly grounded,
and can only be misunderstood by those who have never observed and
followed nature in her operations.

"Thus we are assured that that which is taken for _species_ among
living bodies, and that all the specific differences which
distinguish these natural productions, have no absolute _stability_,
but that they enjoy only a relative _stability_; which it is very
important to consider in order to fix the limits which we must
establish in the determination of that which we must call _species_.

"It is known that different places change in nature and character by
reason of their position, their 'composition' [we should say
geological structure or features], and their climate; that which is
easily perceived in passing over different places distinguished by
special characteristics; behold already a cause of variation for the
natural productions which inhabit these different places. But that
which is not sufficiently known, and even that which people refuse to
believe, is that each place itself changes after a time, in exposure,
in climate, in nature, and in character, although with a slowness so
great in relation to our period of time that we attribute to it a
perfect _stability_.

"Now, in either case, these changed places proportionately change
the circumstances relative to the living bodies which inhabit them,
and these produce again other influences on those same bodies.

"We see from this that if there are extremes in these changes there
are also gradations (_nuances_), that is to say, steps which are
intermediate, and which fill up the interval; consequently there are
also gradations in the differences which distinguish that which we
call _species_.

"Indeed, as we constantly meet with such shades (or intermediate
steps) between these so-called _species_, we find ourselves forced
to descend to the minutest details to find any distinctions; the
slightest peculiarities of form, of color, of size, and often even
of differences only perceived in the aspect of the individual
compared with other individuals which are related to it the more by
their relations, are seized upon by naturalists to establish
specific differences; so that, the slightest varieties being
reckoned as species, our catalogues of species grow infinitely
great, and the name of the productions of nature of the most
interest to us are, so to speak, buried in these enormous lists,
become very difficult to find, because now the objects are mostly
only determined by characters which our senses can scarcely enable
us to perceive.

"Meanwhile we should remember that nothing of all this exists in
nature; that she knows neither classes, orders, genera, nor species,
in spite of all the foundation which the portion of the natural
series which our collection contains has seemed to afford them; and
that of organic or living bodies there are, in reality, only
individuals, and among different races which gradually pass
(_nuancent_) into all degrees of organization" (p. 14).

On p. 70 he speaks of the animal chain from monad to man, ascending from the most simple to the most complex. The monad is the most simple, the most like a germ of living bodies, and from its nature passes to the volvoces, proteus, vibrios; from them nature arrives at the production of "polypes rotifères"--and then at "Radiaires," worms, Arachnida, Crustacea, and Cirrhipedes.

FOOTNOTES:

[162] _Discours d'ouverture du Cours de Zoologie donné dans le Muséum national d'Histoire naturelle, le 21 floréal, an 8 de la République_ (1800). Floréal is the name adopted by the National Convention for the eighth month of the year. In the years of the Republic 1 to 7 it extended from April 20 to May 19 inclusive, and in the years 8 to 13 from April 21 to May 20 (_Century Cyclopedia of Names_). The lecture, then, in which Lamarck first presented his views was delivered on some day between April 21 and May 20, 1800.

[163] Lamarck by the word _génération_ implies heredity. He nowhere uses the word _hérédité_.

[164] "L'oiseau que le besoin attire sur l'eau pour y trouver la proie qui le fait vivre, écarte les doigts de ses pieds lorsqu'il veut frapper l'eau et se mouvoir à sa surface" (p. 13). If the word _veut_ has suggested the doctrine of appetency in meaning has been pushed too far by the critics of Lamarck.

[165] This he already touched upon in his _Mémoires de Physique et d'Histoire naturelle_ (p. 342).

[166] _Système des Animaux sans Vertèbres_, pp. 16 and 17.

[167] I have cited the incontestable proofs in my _Hydrogéologie_, and I have the conviction that one day all will be compelled to accept these great truths.

[168] _Ranunculus aquaticus capillaceus_ (Tournef., p. 291).

[169] _Ranunculus aquaticus_ (folio rotundo et capillaceo, Tournef., p. 291).

[170] _Gramen junceum_, etc. (Moris, hist. 3, sec. 8, t. 9, f. 4).

[171] _Discours d'ouverture d'un Cours de Zoologie, prononcé en prairial, an XI, au Muséum d'Histoire naturelle, sur la question, Qu'est-ce que l'espèce parmi les corps vivans?_ (1803).

[172] _Recherches sur l'Organisation des Corps vivans_, p. 9.

[173] "See at the end of this discourse the sketch of a _Philosophie zoologique_ relative to this subject." [This sketch was not added--only the title at the end of the book.]

[174] See the _Annales du Muséum d'Hist. nat._, IV^e cahier. 1., 1802, pp. 302, 303: _Mémoires sur les Fossiles des Environs de Paris_, etc. He repeats in his _Discours_ what he wrote in 1802 in the _Annales_.

[175] _Ibid._ This is repeated from the article in the _Annales_.

[176] _Ibid._ "See my _Recherches sur les Corps vivans_" (Appendix, p. 141).

[177] _Discours d'Ouverture du Cours des Animaux sans Vertèbres, prononcé dans le Muséum d'Histoire naturelle en mai 1806._ (No imprint. 8^o, pp. 108.) Only the most important passages are here translated.

[178] "We know that all the forms of organs compared to the uses of these same organs are always perfectly adapted. But there is a common error in this connection, since it is thought that the forms of organs have caused their functions (_en ont amené l'emploi_), whereas it is easy to demonstrate by observation that it is the uses (_usages_) which have given origin to the forms of organs."