Zoological Philosophy
by
J. B. Lamarck
[This translation, which has been prepared by Ian
Johnston of Malaspina University-College,
Nanaimo, BC, Canada, (now Vancouver Island University) is in the public domain,
and may be used by anyone, in whole or in part, without permission and without
charge, provided the source is acknowledged, released September 1999]
First Part
Considerations of the Natural
History of Animals, Their Characteristics, Their Interrelationships, Their
Organic Structure, Their Distribution, Their Classification and Their Species
Chapter Four
General Observations Concerning
Animals
Generally
considered, animals include living beings truly remarkable for faculties unique
to them and at the same time worthy of our admiration and study. These beings, infinitely diversified in their forms, organic
structures, and faculties, are capable of movement or of moving certain parts
without the impetus of any communicated movement but by a cause which
stimulates their irritability, a cause which, in some, is produced from within
and, in others, is entirely outside them. For the most part, animals enjoy the
ability to change their location, and they all possess eminently irritable
parts.
We
observe that in moving about some animals crawl,
march, run, or jump, while others fly, raising themselves in the air and
travelling through different spaces. Others, living in the depths of the
waters, swim and transport themselves to different areas in the expanse of the
surroundings waters.
The
animals are not, like the plants, in a situation where they find within range
right next to them the material on which they feed. Among animals, even those
which live by seizing prey must go seek it out, follow it, and finally seize
it. Thus, they must have a faculty of motion and even of moving around so as to
be able to obtain the nourishment which they require.
Moreover,
those animals which multiply by sexual reproduction do not offer sufficiently
perfect hermaphrodites to enable them to meet their needs, and thus it is again
necessary that they can move around to put themselves in a situation where they
can reproduce. For those animals which, like the oysters, cannot change their
positions, the environmental surroundings must provide means for such movement.
Thus,
these needs have the capacity to provide the faculty which the animals possess
of moving parts of their bodies and of carrying out movements advantageous to
their own conservation and that of their race.
In the
second part we will look into the source of this astonishing faculty, as well
as the cause of the most remarkable which we find among them. But in the
meantime, so far as the animals are concerned, we will state that it is easy to
recognize the following points:
(1)
Some do not move or move their parts only as a consequence of their stimulated
irritability. But they do not experience any feeling and cannot have any sort
of will power. These are the most imperfect animals.
(2)
Others, apart from movements which their parts can undergo through their
stimulated irritability, are susceptible to experiencing sensations and possess
an intimate and very obscure feeling of their existence. But they act only
through an interior impulse by a tendency which draws them to some object or
other, so that their will power is always dependent and led on.
(3)
Still other animals not only experience movements in some parts as a result of
their stimulated irritabilty, are susceptible to
receiving sensations, and enjoy an inner feeling of their existence, but, in
addition, have the ability to form ideas for themselves, although confused, and
to act by a determining will power, which is nevertheless subject to tendencies
which carry them, once again, exclusively towards certain particular objects.
(4)
Finally, some other animals, the most perfect, possess to a high degree all the
abilities of the preceding ones and enjoy, in addition, the power of forming
for themselves clear or precise ideas of objects which have affected their
sense and drawn their attention, of comparing and combining these ideas up to a
certain point, and deriving from them judgments and complex ideas. In a word,
they have the ability to think and to have a less captive will power, which
permits them to vary their actions to a greater or lesser extent.
In the
least perfect animals, life is without energetic movements, and irritability
alone is then sufficient for vital movements. But since vital energy increases
in proportion to the complexity of organic structures, there comes a limit
where in order to provide sufficiently for the activities essential to vital
movements, nature had to add to its means. And for that reason, she used
muscular action to establish a system of circulation, from which followed the
acceleration of the movements of fluids. This acceleration itself later grew in
proportion to the muscular power which it required. Finally, since no muscular
activity can take place without the action of nerves, the latter were
everywhere found necessary to the acceleration of the fluids in question.
In
this way nature was capable of adding to the irritability, once insufficient,
muscular action and neural influence. But this neural influence which gives
rise to muscular action never brings it about by the path of feeling, something
I hope to demonstrate in the second part. Later I will establish there that
feeling is not at all necessary for the carrying out of vital movements, even
in the most perfect animals.
Thus,
the different existing animals are clearly distinguished from each other, not
only by the particular features of their external shape, the consistency of
their bodies, their size, and so on, but, in addition, by the faculties with
which they are endowed. Some, like the most imperfect, find themselves reduced,
in this respect, to the most limited state, not having any faculties other than
those appropriate for life, not moving except through a power outside
themselves; whereas, the others have progressively more numerous and more
eminent faculties, to the point where the most perfect display a collection of
faculties exciting our admiration.
These
astonishing facts cease to surprise us when we first recognize that each
acquired faculty is the result of a special organ or system of organs which
gives rise to it and when later we see that from the most imperfect animal,
which has no particular organ whatsoever and consequently no other faculty that
those which belong to life itself, right up to the most perfect animal, the
most richly endowed with faculties, the organic structure gradually gets more
complex, in such a way that all the organs, even the most important, arise one
after the other through the extent of the animal ladder, then successively
perfect themselves by the modification which they undergo and which
accommodates them to the state of their organic structure of which they are a
part. Finally, through their combination in the most perfect animals they
present the most complex organic structures, which produce the most numerous
and most eminent faculties.
Considering
the internal organic structure of animals, the different systems which this
organic structure presents throughout the extent of the animal ladder, and
finally, the various specialized organs is thus the most important of all the
ideas which must direct our attention in the study of animals.
If
animals, looked upon as productions of nature, are living beings particularly
astonishing for their faculty of movement, a large number of them are
considerably more astonishing for their faculty of feeling.
But
just as this faculty of movement is very limited in the most imperfect animals,
where it is not at all voluntary and where it does not occur except through
external stimuli, so it improves later more and more. It succeeds in
originating within the animal itself and finishes by being subject to the
animal’s will power. Similarly the faculty of feeling is also very obscure and
limited in the animals where it begins to occur, so that it develops
progressively later and, having attained its main development,
it manages to bring into existence in the animal the faculties which constitute
intelligence.
In
fact, the most perfect animals have simple and even complex ideas, passions,
memory, a source of dreams, that is to say, they experience involuntary returns
of their ideas, even their thoughts, and are up to a certain point capable of
instruction. How admirable a result of nature’s power this is!
To
succeed in giving a living body the ability to move itself without the impetus
of a communicated force, to perceive objects beyond itself, to form ideas for
itself, by comparing the impressions which it has recieved
from them with those which it was able to receive from other objects, to
compare or combine these ideas, and to produce judgments which are for it ideas
of another order, in a word, to think, that is not only the greatest marvel
which the power of nature has been able to achieve but, in addition, it is the
proof that a considerable time has been taken up, for nature achieves nothing
except step by step.
Compared
to the lengths of time which we consider great in our ordinary calculations, it
has undoubtedly required an enormous length of time and considerable variation
in the sequence of circumstances for nature to have been able to lead the
organic structure of animals to the degree of complexity and development where
we see it in those who are the most improved. Thus, we justified in thinking
that, if the analysis of these varied and numerous strata making up the
exterior crust of the earth is an indisputable testament to its great age and
if a consideration of the very slow but continuous displacement of the sea
basin (1), as evidenced by the numerous
monuments to its passage which it has left everywhere, confirms once again the
prodigious antiquity of the terrestrial globe, then a consideration of the
degree of improvement which the organic structures of most animals must have
reached helps, in its turn, to provide the highest quality evidence of this
truth.
But in
order to establish firmly the basis of this new proof, it will be necessary
first to bring fully to light the proof relevant to the progress in organic
structures themselves. It will be necessary to ascertain, if possible, the
reality of this progress. And finally it will be necessary to collect the best
established facts in this matter and to indicate the means which nature
possesses to give to all its productions the existence which they enjoy.
Let us
note, meanwhile, that although it is generally acceptable, in referring to the
beings which make up each kingdom, to indicate them under the general term
productions of nature, it nevertheless appears that people have no clear idea
associated with this expression. It seems that the prejudice against a
particular origin prevents us from recognizing that nature possesses the
ability and all the means to bring to life so many different beings on her own,
continually to vary, although very slowly, the races of those which enjoy life,
and to maintain throughout the general order which we observe.
Let us
leave aside all opinions whatsoever concerning these important matters, and so
as to avoid all imaginative errors, let us consult throughout the very acts of
nature.
In
order to be able to include, in our thinking, all existing animals and to place
these animals in a perspective easy to grasp, it is appropriate to recall that
all the natural productions which we can observe have been divided up by
naturalists, for a long time now, into three kingdoms, under the denominations
animal kingdom, vegetable kingdom, and mineral kingdom. By this division, the
entities comprising each of these kingdoms have been set up comparatively, as
if on the same line, although some have an origin very different from others.
For a
long time now, I have found it more convenient to use another primary division,
because it is appropriate for making us more aware in general terms of all the
entities which are the purpose of the enquiry. This, I separate all the natural
productions comprising the three kingdoms which I have just pointed out into
two main branches, as follows:
(1) organically structured bodies which are alive;
(2) raw bodies without life.
Existing
beings, or living bodies, like the animals and plants, make up the first of
these two branches of the productions of nature. These beings have, as everyone
knows, the ability to feed themselves, develop, reproduce, and are necessarily
subject to death.
But
what people do not so readily know, because prevailing hypotheses do not allow
them to believe it, is that living bodies, as a result of their organic action
and faculties, as well as the mutations which bring about in them organic
movements, form themselves their own substance and secretory
material (Hydrogéologie, p. 112). What people
understand even less is that through their remains these living bodies give
rise to the existence of all the composite materials, raw or inorganic, which
we observe in nature. The various types of this material multiply in nature
over time according to the circumstances of their location, through changes
which they undergo imperceptibly and which simplify them more and more and
lead, after a great deal of time, to the complete separation of the main
elements composing them.
These
are the various raw non-living materials, solid or liquid, which comprise the
second branch of the productions of nature and which, for the most part, are
known under the name minerals.
One
can say that between raw materials and living bodies there is an immense hiatus
which does not allow us to rank on the same line these two sorts of bodies, nor
to undertake to link them by any modification, something which has been
attempted but in vain.
All
the known living bodies divide themselves neatly into two particular kingdoms,
based on essential differences which distinguish animals from plants. In spite
of what people have said about this, I am convinced that there is no longer a
real point of subtle melding between these two kingdoms and that,
consequently, that there are no animal-plants (something expressed in the word
zoophyte) nor plant-animals.
The
irritability in all or in certain parts is the most general characteristic of
animals. That is more common than the faculty of voluntary movements and of
feeling, more even that that of guiding oneself. Now,
all the plants, without omitting even the plants
called sensitive, nor those which move certain of their parts at the first
touch or at the first contact with air, completely lack irritability. I have
observed this point elsewhere.
We know
that irritability is a faculty essential to the parts or some of them in
animals. The actions of irritability are never suspended or destroyed so long
as the animal is alive and the irritable part has not suffered any lesion in
its organic structure. The effect of irritability consists of a contraction
which the entire irritable part undergoes instantaneously on contact with a
foreign body. The contraction stops with the cause and comes again, after the
relaxation of the part, when new contacts happen to irritate it. Now, nothing
like this has ever been observed in any part of plants.
When I
touch the extended branches of a sensitive (mimosa pudica),
instead of a contraction, I observe immediately in the attachments of the
branches and disturbed petioles, a relaxation which allows these branches and
petioles of the leaves to collapse, something which makes even the leaflets in
this case droop down on one another. Once this drooping occurs, it is a waste
of time to touch the branches and the leaves of the plant again; the effect
does not recur. A relatively long time is needed, unless it is very hot, for
the cause which can swell the articulations of the small branches and the
leaves of the sensitive to raise again and extend all
its parts and to deal with the sagging in such a way that it can happen again
through contact or a light tremor.
I do
not recognize in this phenomenon any connection with irritability in animals.
But I do know that with plants during periods of growth, above all when it is
hot, a great deal of elastic fluid is created, some of which is exhaled
constantly. Thus I have concluded that in leguminous plants, these elastic
fluids can gather particularly in the articulations of the leaves before
dissipating and that they can there strain these joints and extend out the
leaves or leaflets.
In
such a case, the slow dissipation of the elastic fluids we are talking about,
stimulated in the legumes by the arrival of night or the sudden dissipation of
the same fluids stimulated in the mimosa pudica by
a small tremor gives rise, in the legumes generally, to the phenomenon known by
the term plant sleep and in the sensitive to what people attribute incorrectly
to irritability (2). Since, as a
consequence of observations which I reveal further on and the conclusions I
have drawn from them, it is not generally true that animals are feeling beings,
all endowed, without exception, with the power of making voluntary acts and,
consequently, having the option of moving at their own will, the definition
which has been given of animals up to the present to distinguish them from
plants is totally inappropriate. Thus I have already proposed to
substitute for it the following, on the ground that it conforms more closely to
the truth and is more appropriate for characterizing the beings which
constitute both kingdoms of living bodies.
Definition
of Animals
Animals
are living organic bodies, endowed with permanently irritable parts; almost all
of them digest the food with which they are nourished,
and being subject to motion, some as a result of will power, whether free or
dependent, and others as a result of their stimulated irritability.
Definition
of Plants
Plants
are living organic bodies, never having irritable parts, not digesting
anything, and not subject to motion, either by will power or by real
irritability.
In
accordance with these definitions, which are much more precise and better
grounded than those which have been used up to now, we are aware that animals
are preeminently distinguished from plants by the
irritability which manifests itself in all their parts or some of them and by
the movements which they can produce in these parts or which are stimulated
there, thanks to their irritability, by external causes.
Undoubtedly
it would be wrong to accept these new ideas on the basis of a simple
introduction. But I think that all unprejudiced readers who take into
consideration the facts which I will lay out in the course of this work and my
observations concerning them will be unable to deny that they are better that
the ancient views which I am replacing with them, because these ancient ideas
are obviously contradicted by everything we observe.
Let us
conclude these general opinions on animals with two quite curious
considerations. The first concerns the extreme multiplicity of animals on the
surface of the earth and those found in the depths of the waters. The second
deals with the means which nature employs so that their number never harms the
preservation of what she has produced or the general order which must prevail.
Among
the two kingdoms of living bodies, the one which consists of animals appears
much richer and more diverse than the other; at the same time it is the kingdom
which presents, in its organically structured products, the most admirable
phenomena.
The
surface of the earth, the depths of the waters, and, in some sense, even the
air, are inhabited by an infinite number of various animals, whose races are so
diversified and numerous that it is probable a large part of them will always
elude our research. There is even more reason to think this given that the
enormous extent of the waters, their depth in a great many places, and the
prodigious fecundity of nature in the smallest spaces will undoubtedly always
be an almost invincible obstacle to the advancement of our understanding of the
subject.
For
instance, one class of invertebrate animals by itself, the insects, in the
number and the diversity of the objects which it includes, is equivalent to the
entire plant kingdom. The class of polyps is probably much more numerous still.
But we will never be able to congratulate ourselves that we know the total
number of animals making up that class.
As a
result of the extreme multiplication of small species, above all of the most
imperfect, the quantity of individuals could injure the preservation of races
and of the progress acquired by the improvement in organic structure, in a
word, of the general order, if nature had not taken precautions to restrict
this multiplication within limits which it can never cross.
Animals
eat one another, except those which live on plants. But the latter run the risk
of being eaten by carnivorous animals.
We
know that the strongest and the best armed are the ones which eat the more
feeble and that the large species devour the smaller ones. However, individuals
of the same race rarely eat each other. They make war on other races.
The
multiplication of the small animal species is so great and the renewal of their
generations so quick that these small species would make the earth
uninhabitable for others if nature had not placed a limit on their prodigious
reproduction. But since they serve as prey for a multitude of other animals,
since the length of their lives is very limited, and since cooler temperatures
kill them off, their quantity is always maintained at just the right
proportions for the preservation of their races and of the others.
As for
the larger and stronger animals, they would be in a position to become dominant
and to threaten the preservation of many other races if they were able to
reproduce in very large numbers. But their races prey on each other and they
reproduce only slowly and in small numbers at any one time. This fact once
again preserves the equilibrium of the species at the right level.
Finally,
man alone, considered apart from everything unique to him, seems
able to reproduce indefinitely. For his intelligence and his methods protect
him from seeing his numbers halted by the voracity of
any of the animals. He exercises such a supremacy over them that instead of
having to fear the largest and strongest animal races, he is able to destroy
them, and every day he reduces their individual numbers.
But
nature has given him numerous passions which, unfortunately, develop along with
his intelligence, thus placing a large obstacle to the extreme multiplication
of the individuals of his species.
In
fact, it seems that man himself is charged with constantly reducing the number
of those like himself. For I am not
afraid to state that the earth will never be covered with the population which
she can feed. Several of its habitable parts will always be alternately
very lightly populated, although the time periods for these fluctuating
alterations for us will be infinite.
Thus,
by wise precautions, everything perpetuates itself in the established order.
Changes and constant renewals seen in this order are held within limits which
they cannot cross. The races of living bodies all remain despite their
variations. The progress acquired in the improvement of organic structure has
lost nothing. Everything which seems disorder, reversal, anomaly constantly
returns to the general order and even contributes to it. And everywhere and
always the will of the sublime Author of nature and of all that exists is
invariably brought about.
Now,
before busying ourselves with a demonstration of the degradation and the
simplification which exist in the organic structures of animals, as we proceed
from the most complex to the simplest, following common practice, let us
examine the present state of their distribution and classification, as well as
the principles which have been used to establish these. Then it will be easier
to recognize the proofs for the degradation in question.
Notes to Chapter Four
(1)
Hydrogéologie, p. 41 ff. [Back to Text]
(2)
In another work (Hist. nat. Des Végétaux, éditon de Déterville, vol.I, p. 202) I have dealt with some other similar
phenomena observed in plants, for example, in hedysarum
girans, dionoea
muscipula, the stamens of the flowers in berberis, and so on, and I have revealed that the
odd movements which we see in the parts of certain plants, principally in hot
weather, are never the result of real irritability, or really of any of their
fibres; they are rather sometimes hygrometic or pyrometric effects, sometimes the results of elastic
relaxation which takes place under certain circumstances, and sometimes caused
by swelling and weakening of parts, by the more or less rapid local
accumulation and dissipation of invisible elastic fluids which the plants must
excrete. [Back
to Text]
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