Even in the mixed populations of modern states, the connection of mental with physical heredity is manifest. Commenting on the population of France, Dr. Collignon observes: “To the difference of races, a purely anatomical fact attested by the form of the skull, the colour of the eyes and hair, and similar bodily traits, there corresponds a cerebral difference, which shows itself in the prevailing direction of the thoughts, and in special aptitudes.” These contrasts are shown by the statistics of Jacoby, who examined the birth and lineage of the most eminent men of France in all departments of activity. He found that the Normans were decidedly ahead in the exact sciences and practical affairs, while in poetry, romance, and works of imagination in general the people of the Midi were far superior to them. Heredity is believed to present itself in another aspect, which has excited much attention. I refer to that form of it called “atavism” or “ancestral reversion,” or “retrogression,” in which a child “takes after,” not his immediate parents, but some remote ancestor; even, as has been often claimed, so remote as beyond the limits of our own species. Such traits have been called “pithecoid” (ape-like) reversions, as they are alleged to be derived from some four-footed precursor of man, an ape, or even a lemur. Evolutionists whose enthusiasm transcended their discretion have pointed out many such features in the human skeleton. A few years ago (1894) I gathered these together, and in a paper read before the American Association for the Advancement of Science, I undertook to prove that these features can be satisfactorily explained by mechanical and functional processes acting in the individual life or in that of his immediate ancestors, and that we have no occasion to appeal to hypotheses of descent, which have, at least, never been proved. Other American anatomists (Bowditch, Baker) endorsed and supported by further evidence this position, so that physical anthropologists, in our country at least, have said less about atavism than formerly; and the final blow to it has been dealt quite lately by a Dutch writer, Dr. Kohlbrügge. He has established the thesis that “all so-called atavistic anomalies are meaningless for the race-type. They are brought about by arrests of development or general variability. They depend on disturbances of nutrition, leading to excess or deficiency of productive energy, presenting a deceptive appearance of progressive or retrogressive evolution.” The consideration of these questions in physical heredity is necessary in psychology, whether individual or ethnic, not merely because the laws of physical run parallel to those of psychical life, but as well for the valuation of those expressions about “men recurring to their brute ancestors” in habits or feelings, so frequent in popular literature.