to the environment for the final solution of many of the great problems of Nature. In this case we have to do with one of the most sudden and radical changes of environment known to man. Every condition of city life, mental as well as physical, is at the polar extreme from those which prevail in the country. To deny that great modifications in human structure and functions may be effected by a change from one to the other is to gainsay all the facts of natural history.
Our long series of articles now draws to a close. It has been shown with what infinite pains, slowly through hundreds of generations, human beings in Europe have been shaping themselves to the conditions imposed by Nature. We have followed men in their migrations over the face of the continent; we have analyzed the forces making for change, which have played upon them; we have seen how tenaciously they have clung to the type of their ancestors throughout all the vicissitudes of ages. Whether twentieth-century urban life, with all the social changes which it implies, will finally eradicate all traces of ethnic descent remains to be seen. Certainly the pages of ethnic history, written in man's physical constitution, are rapidly blurring before our eyes. To be deciphered at all, they require the instant attention of European scientists. As for us in America, our field of investigation is mapped out with equal clearness. We know with some certainty, thanks to the unselfish and stupendous exertions of such men as Beddoe, Collingnon, Ranke, Livi, and a host of their fellows in Europe whose work we have been outlining, what is the raw material of which our heterogeneous American population is to be composed. They have analyzed the sources of the great human stream which is flowing continually westward to our shores. They have acquainted us with the physical character of the communities whence come those who, as immigrants, cast in their lot with America for good or ill. It behooves us at once to know whether we are drawing off the scum, the lees, or the pure waters in this inflowing tide. Then, again, we have to determine the effects of this novel life—its climate, its social conditions, its material prosperity, and, above all, its ceaseless intermingling of all strains and classes—upon the physical constitution of the original ethnic stocks. Such are the problems which confront us. May we take up the scientific burden where our European confrères must of necessity lay it down; and, in the same devotion to knowledge for its own pure sake, bear it a step further along the way!
