this we know, the fact exists, and we find its general explanation in the conditions of existence, in the conditions of the environment.
Now, man, who has progressed upon the earth a much longer time than the turkey or the rabbit, who has been upon the globe for thousands of years, living under the most diverse, the most opposite conditions, multiplying further the causes of modification by his manners, his habits, his kind of life, by the more or less care he takes of himself—man, I say, is certainly found in conditions of variation much more marked than those which have been encountered by the animals we have cited. It is not, then, surprising that men, from one group to another, present differences of which we here see the specimens. If there is any thing in them to astonish us, it is that these differences are not more considerable.
In your turn you ask of the polygenesists—for this is the name given to the philosophers who believe in the multiplicity of the human species—how is it that when the white man comes to any country whatever, at the antipodes, in America, in Polynesia—how is it, I say, that everywhere he crosses with human groups that differ most completely from him; that these unions are always fertile, and that everywhere he has left traces of his passage in producing a mixed population?
If you press your interlocutor a little, he will quite often deny the reality of species; he will thus put himself in contradiction with all naturalists without exception, botanists or zoologists—with all the eminent minds who, following Buffon, Tournefort, Jussieu, Cuvier, Geoffroy Saint-Hilaire, have studied vegetables and animals, outside of all discussion, and without thought of man.
In thus dealing with the question, the polygenesist falls into disagreement with the best established science.
Sometimes, also, you will hear him declare that man is an exception, that he has his particular laws, that the arguments taken from plants and animals are not applicable to him. Answer him, then, in the name of physiology, in the name of all the natural sciences, that he is certainly mistaken.
It is quite as impossible that an organized and living body should escape the laws of organization and life as that material substances should escape the laws that govern inorganic matter. Therefore, man, an organized and living being, obeys, as such, all general laws, and those of crossing like the rest. The conclusion we have drawn is then legitimate, and the nature of the arguments employed to combat it is a further proof in its favor.
Gentlemen, the subject of this lecture, which has occupied about an hour, at the Museum took up an entire course. The exposition has necessarily been brief. But I hope you have seen reasons strong enough to make you accept my view.
If doubts remain, try to come to my lectures. Some of you will be able, perhaps. I sometimes see working-men on the seats of my lec-
