Definition of Animals and Plants

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.

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.

Let us conclude these general opinions on animals with two quite curious considerations. The first concerns

1. The extreme multiplicity of animals on Earth

2. How nature preserves the general order

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.

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.

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.

Everywhere and always the will of the sublime Author of nature and of all that exists is invariably brought about.