Page:Popular Science Monthly Volume 3.djvu/160

150 better in life than another. It will have every chance, then, of leaving a more numerous posterity. If the advantageous modification is transmitted, which may occur through hereditary tendency, the descendants of this individual will have, in their turn, the chance of succeeding better than their contemporaries. The modification, then, in all probability, will go on becoming more general, by the same law of fatality that causes a strong people to absorb a weak one: so that, after a longer or shorter time, the whole race will end by presenting the modification which was only individual at the outset. And since there was no reason why the same phenomenon, so natural and so simple, should not be repeated indefinitely, with all imaginable variations, we understand how it may result, in the infinite lapse of time, in that multiplicity of forms and characters which distinguishes animal species to our eyes.

Darwin says, in those pages in which he treats of instinct, that, if it were possible to prove that a habit might become hereditary, all distinction between habit and instinct would absolutely vanish. Darwin's literary procedure is that of always urging his reader further than he seems to go himself. He suggests the best arguments in the world with a doubtful air, and one is every moment surprised to find one's self so strongly convinced when the author seems convinced so little. And, in fact, we cannot deny that young puppies often come to a point the very first time they are sent out hunting, and that even better than others after long training. The habit of saving life is hereditary in some breeds, just as the shepherd's dog has the habit of walking around the flock. All these acts are performed, without the aid of experience, by the young as well as the old, and certainly apart from any notion of the object—at the first time, at least. The objection is idle that only those habits imposed by men on brutes are transmitted in this way. More than one instance, taken from wild animals, proves the contrary. The best is perhaps that which we see done by a bird of our own country, the oriole. It has a very peculiar cradle-shaped nest, hung from the fork of a branch, sewed at the edges with flexible grass, and always with bits of string, shreds, or packthread. There is no oriole's nest without some fastening worked by man's hand. If this is a habit, it is hereditary; if it is an instinct, it will be admitted at least that it does not go back to the beginning of the world.

From birth, one individual, or several individuals of the same species, placed in similar conditions, have had some habit. One of two things: this habit is injurious, or it is useful; it is either good or bad, from the point of view of the preservation of the individual, and consequently of the species. If it is injurious, it necessarily tends to disappear, either with the individual which has taken it on, or with the descendants which will inherit from it. If the habit is favorable, it has the chance of transmitting itself under the form of an instinct. This instinct, at first confined to a few individuals of the same blood,