From all of this the one caution follows. At best, sterilization is not likely to be a final solution of this problem. We may, and indeed I believe must, use it as a help, as something that will contribute toward the solution, until we can get segregation thoroughly established. But in using it, we must realize that the first necessity is the careful study of the whole subject, to the end that we may know more both about the laws of inheritance and the ultimate effect of the operation. CONCLUSION AND RÉSUMÉ The Kallikak family presents a natural experiment in heredity. A young man of good family becomes through two different women the ancestor of two lines of descendants,--the one characterized by thoroughly good, respectable, normal citizenship, with almost no exceptions; the other being equally characterized by mental defect in every generation. This defect was transmitted through the father in the first generation. In later generations, more defect was brought in from other families through marriage. In the last generation it was transmitted through the mother, so that we have here all combinations of transmission, which again proves the truly hereditary character of the defect. We find on the good side of the family prominent people in all walks of life and nearly all of the 496 descendants owners of land or proprietors. On the bad side we find paupers, criminals, prostitutes, drunkards, and examples of all forms of social pest with which modern society is burdened. From this we conclude that feeble-mindedness is largely responsible for these social sores. Feeble-mindedness is hereditary and transmitted as surely as any other character. We cannot successfully cope with these conditions until we recognize feeble-mindedness and its hereditary nature, recognize it early, and take care of it. In considering the question of care, segregation through colonization seems in the present state of our knowledge to be the ideal and perfectly satisfactory method. Sterilization may be accepted as a makeshift, as a help to solve this problem because the conditions have become so intolerable. But this must at present be regarded only as a makeshift and temporary, for before it can be extensively practiced, a great deal must be learned about the effects of the operation and about the laws of human inheritance. INDEX Abigail, 28. Albert, 24. Alcoholism, 18, 26. of the good side, 29, 30. in the bad family, 67. children, 25. Guss Saunders, a victim, 93. in the two branches compared, 67. Almshouse, 28. Almshouses reduced if feeble-minded were cared for, 105. Asexualization, 107. B----, the town mentioned, 79. Barrah, Eunice, 26. Beede, 29. Bible of Casper Kallikak, 100. Binet tests in the public schools, 71. used with the Kallikak family, 88, 89. Charts, heredity, 33-49. Children of Althea Haight, 23. Colonies for feeble-minded, 105.