150 THE POPULAR SCIENCE MONTHLY. 



ceed 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 de- 

 scendants of this individual will have, in their turn, the chance of suc- 

 ceeding 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 varia- 

 tions, 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 distinc- 

 tion between habit and instinct would absolutely vanish. Darwin's lit- 

 erary 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 clone 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 spe- 

 cies, 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 con- 

 sequently of the species. If it is injurious, it necessarily tends to dis- 

 appear, 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, 



