what it ought to be, and yet there are some respecting which information is particularly important to us. Inasmuch as a transformation of the organism constitutes the principal element of a durable acclimatization, it is not the individual alone who is affected by a prolonged sojourn away from his native country, but his entire posterity as well. We can not, therefore, deny that this side of the question is the most important of all. There is one point of view from which the study of the transformations acquires a general interest of really vast extent. It is that of their relations with the history of the human race. Two questions occur at once to all who seek to arrive at a clear idea of the manner in which man has reached his present condition. Is it true that the different human races and varieties are issues from a common stock? And what are the causes of their diversity? It is of no use for our friends the zoölogists to preach transformism to us. That may do very well of itself when we have only an affair of building up a system. But, unfortunately, no man has ever yet observed the transformation from one race to another. No one has, for example, seen a people of the white race become black under the tropics, or negroes transplanted to the polar regions or to Canada metamorphosed into whites. The question whether color is related to climate still remains to be solved, experimentally at least; data bearing on the subject are still absolutely wanting. I confess that, if any one should ask me for the slightest light respecting the origin of races, I should not be in a condition to give a plausible argument or an experimental fact that would be competent to justify any point of view whatever. It is nevertheless true that, at the bottom of every impartial study of the phenomena of acclimatization, we arrive inevitably at the old point of view of Hippocrates, and that the existence of a relation between the somatic properties of man and certain geographical circumscriptions is not doubtful. That is what my friend Bastian understands by the term ethnological provinces. The reality of such provinces is incontestable; and they have the same significance with reference to man as zoölogical and botanical provinces in the geographical distribution of plants and animals. We can not deny that we have also the right to premise the existence of general laws of acclimatization which apply to plants and animals as well as to man—at least so far as regards the modifications of classes.
The prime question for us relates to the aptitude which the white man has manifested for acclimatization through all his historical evolution. To what point have we a right to conclude, from the data furnished by history, that the white man can find, outside of the limits of his country, conditions favorable to his existence? To bring up the vital point of the problem at once, the white man is not everywhere the same. Scientific experiment is every day tending to bring into more prominent relief the sharp differences in this matter which exist among the different subdivisions of the white race which we narily
