In ultimate origin all evolution and all heredity are the outcome, summation, and expression of the effects of environmental influences, acting on the whole organism under certain laws of transmission. The laws of heredity, though as yet only partially determined, are already sufficiently ascertained to prove for practical purposes that, in order to promote integration and further progress in human evolution--not disintegration and degeneration--two things are essential and complementary. On the one hand, we must do everything possible in the direction of improving the nutrition, health, conditions of life, and habits of the community; and, on the other hand, we must promote and encourage parenthood on the part of the best and stablest stocks, and do everything in our power to discourage, or in the extreme cases even to prevent, proliferation of unfit and degenerate strains. For the purpose of the present inquiry we need merely state as a practical preliminary regarding heredity that it has been proved beyond question that if two feeble-minded persons marry they will most probably produce abundant offspring, of whom all may be subnormal, and a large proportion will become a burden on the State; and that if one such person is mated with a healthy individual an undue proportion of their children are likely to prove degenerate or defective, and the unsoundness will continue to make its appearance in succeeding generations. While local evidence confirmatory of this came before the Committee, first place will be given to certain classic and exhaustive investigations and life-histories of degenerate families, going back many generations, such as no young country could possibly supply. However, the forcible and far-sighted report of the late Dr. Duncan Macgregor (originally Professor of Mental Science at Otago University, and subsequently Inspector-General of Asylums, Hospitals, and Charitable Aid), quoted in the Appendix, shows clearly that some very degenerate stocks imported into this country under the active immigration policy of the "seventies" and "eighties" were already threatening, thirty-five years ago, to become a serious tax on the country, as well as tending to lower the high physical, mental, and moral standard established by the original pioneers and settlers. We shall now revert for the moment to the environmental factor. The first most pressing and immediate practical duty of the Government and the community is to spare no pains to improve the status and environment of the family so as to promote the highest attainable standard of physical, mental, and moral health for the new generation--already in our midst or bound to arrive in the course of the next few years.