Page:Popular Science Monthly Volume 2.djvu/502

 around us, and to shield us against the inclemency of the seasons. The animal, in this happier than man, has no need of dress—Nature supplying it with plumage or with fur—but yet is required to build for itself the dwelling-place where it is to find shelter. May we suppose that here, too, Nature provides for every thing, and that blind instinct guides the bee in the construction of her cell, and the bird in the building of its nest? Such, indeed, is the opinion of most naturalists, and their chief argument is drawn from the fact that birds always follow the same plan in building their nests, while man is ever modifying and improving bit by bit his methods of construction. But, now, is this argument based on unquestionable facts, or is the conclusion legitimate? An English naturalist, Mr. Alfred Russel Wallace, undertakes to prove the contrary, in his work on Natural Selection. According to him, the bird does not build its nest by instinct; and the mental faculties it exhibits in this operation are of an identical order with those exhibited by man when he builds a house. In short, it is claimed that these faculties are simply imitativeness, and a sort of rudimentary ratiocination, which can take account of external surroundings, whatsoever they may be. Hence it is that birds do change and improve their processes of construction, under the influence of such causes as determine progress in man; and, in turn, man is at a stand-still when he receives no impetus from without.

What is instinct? It is "the faculty of performing complex acts, absolutely without instruction or previously-acquired knowledge." Instinct, then, would enable animals to perform spontaneously acts which, in the case of man, presuppose ratiocination, a logical train of thought. But, when we test the observed facts which are usually put forward to prove the power of instinct, it is found that they are seldom conclusive. It was on such grounds that the song of birds was taken to be innate, albeit a very ready experiment would have shown that it comes from the education they receive. During the last century Barrington brought up some linnets, taken from the nest, in company with larks of sundry varieties, and found that every one of his linnets adopted completely the song of the master set over him, so that now these linnets—larks by naturalization—formed a company apart when placed among birds of their own species. Even the nightingale, whose native song is so sweet, exhibits, under domestication, a considerable readiness to imitate other singing-birds. The song of the bird is, therefore, determined by its education, and the same thing must be true as to nest-building. A bird brought up in a cage does not construct the nest peculiar to its species. In vain will you supply all the necessary materials: the bird will employ them without skill, and will oftentimes even renounce all purpose of building any thing like a nest. Does not this well-known fact prove that, instead of being guided by instinct, the bird learns how to construct its nest, just as man learns how to build a house? This observation might be made complete, if we were