nally, and has always been, peopled by migrations from the Old World. At the risk of repeating myself, I will briefly sum up the grounds of my conviction.
Permit me first to recall the two rules which I have constantly followed in the solution of the questions, sometimes so ardently contested, which the history of man raises. The first is to put away absolutely every consideration borrowed from dogma or philosophy, and to invoke only science—that is, experiment and observation. The second is, never to isolate man from other organized beings; and to admit that he is subject, as to all that is not exclusively human, to all the general laws which control equally animals and plants. Hence, we can not regard as true any doctrine or opinion which makes man an exception among organized beings.
We make the application of these principles to the question which occupies us, but in a broader way; for it is only a special case of a more general problem which we may formulate in the terms—Man is everywhere now: did he appear everywhere in the beginning? If not absolutely cosmopolitan in its origin, did the race appear at an indefinite number of points? Or, rather, born at a single and limited spot, has it gradually taken possession of the whole earth by migration? At first thought we might suppose that the answer to these questions would be very different according as we admit the existence of one or many human species. That would be a mistake. We purpose to show that polygenists can shake hands with monogenists on this point, without involving themselves in any contradiction. We take, first, the monogenist view.
Physiology, which leads us to recognize the unity of the human race, teaches us nothing in reference to its primary geographical origin. It is otherwise with the science which concerns the distribution of animals and plants over the surface of the globe. The geography of organic beings has also its general facts, which we call laws. These facts—these laws—must be learned and interrogated in order to solve the problem of the manner in which the globe was peopled. The first result of this inquiry is a demonstration that real cosmopolitanism, as we attribute it to man, does not exist anywhere, either in the animal or the vegetable kingdom. I cite a few of the evidences in support of this affirmation.
Take, first, what De Candolle says, that "no phanerogamous plant extends over the whole surface of the earth. There hardly exist more than eighteen the areas of which reach over half the lands; and there is no tree or shrub among the plants of most considerable extension" The last remark touches an order of considerations on which I shall insist further on.