We found that the types which come to our shores do not remain stable, but show such important modifications, that many of the differences of the human types of Europe seem rather ephemeral than permanent, determined more by environment than by heredity. The characteristics which belong to the influences of environment belong to the most fundamental traits of the body. Stature, form of head, and size of face, seem to be equally subject to these influences; and the modifications are the more marked, the less developed the organ in question at the time of birth, the longer it is therefore subject to the influences of environment. This fact allows us to assert with a high degree of confidence that mental traits as well as physical traits will be modified by the effect of environment. When, furthermore, we recall that we could not discover any proofs of the superiority of one type over another, we may feel safe when we state that the dangers to the vigor of the American nation, due to an influx of alien European types, is imaginative, not real. A number of data have also been obtained for a better understanding of the significance of race-mixture. Let us recall that one of the most powerful agents modifying human types is the breaking-up of the continuance of certain strains in small communities by a process of rapid migration, which occurs both in Europe and in America, but with much greater rapidity in our country, because the heterogeneity of descent of the people is much greater than in the countries of Europe. What effect these processes may have upon the ultimate type and variability of the American people cannot be determined at the present time; but no evidence is available that would allow us to expect a lower status of the developing new types of America. Much remains to be done in the study of this subject; and, considering our lack of knowledge of the most elementary facts that determine the outcome of this process, I feel that it behooves us to be most cautious in our reasoning, and particularly to refrain from all sensational formulations of the problem that are liable to add to the prevalent lack of calmness in its consideration; the more so, since the answer to these questions concerns the welfare of millions of people.