We thus have a natural experiment of remarkable value to the sociologist and the student of heredity. That we are dealing with a problem of true heredity, no one can doubt, for, although of the descendants of Martin Kallikak Jr. many married into feeble-minded families and thus brought in more bad blood, yet Martin Jr. himself married a normal woman, thus demonstrating that the defect is transmitted through the father, at least in this generation. Moreover, the Kallikak family traits appear continually even down to the present generation, and there are many qualities that are alike in both the good and the bad families, thus showing the strength and persistence of the ancestral stock. The reader will recall the famous story of the Jukes family published by Richard L. Dugdale in 1877, a startling array of criminals, paupers, and diseased persons, more or less related to each other and extending over seven generations. Dr. Winship has undertaken to compare this family with the descendants of Jonathan Edwards, and from this comparison to draw certain conclusions. It is a striking comparison, but unfortunately not as conclusive as we need in these days. The two families were utterly independent, of different ancestral stock, reared in different communities, even in different States, and under utterly different environment. The one, starting from a strong, religious, and highly educated ancestor, has maintained those traits and traditions down to the present day and with remarkable results; the other, starting without any of these advantages, and under an entirely different environment, has resulted in the opposite kind of descendants. It is not possible to convince the euthenist (who holds that environment is the sole factor) that, had the children of Jonathan Edwards and the children of “Old Max” changed places, the results would not have been such as to show that it was a question of environment and not of heredity. And he cites to us the fact that many children of highly developed parents degenerate and become paupers and criminals, while on the other hand, some children born of lowly and even criminal parents take the opposite course and become respectable and useful citizens. In as far as the children of “Old Max” were of normal mentality, it is not possible to say what might not have become of them, had they had good training and environment.