||34 TWENTIETH ANNUAL REYNOLDS LECTURE more information on the part that heredity plays in human beings should be available. It may be best that with our limited knowledge we are forced to go slowly in such an undertaking. It is fortunate that man is subject to change by mutation and by the recombination of genes, thereby providing a means by which he can meet new conditions and new environments. A genetic makeup that is suitable in one environment may be at a disadvantage in another. It has been said that undesirable anomalies in the human race are the price man pays for this plasticity. As he assumes the responsibility for changing his environment he must assume the responsibility of directing his inheritance. Probably little can be done at first, but gradually as he gains knowledge of the principles and problems involved, headway can be made. The human geneticist discovers and explains the part heredity plays. The knowledge he gains should serve as a tool to be used by physicians dealing with the cause, diagnosis, and treatment of diseases, and by social scientists and others dealing with human problems of behavior. The building of a superior human race is not a short-time project, nor does it involve better education and environmental conditions alone. Somehow, little by little, man will find ways to understand and improve himself genetically. As he does so, he can better make use of his environment and educational opportunities. As his environment is improved, he can better understand and improve his heredity. We must recognize the fact that man is a changing organism possessing the necessary possibilities for failure and success. The responsibility for his course rests on his own shoulders. Whether or not he will assume this great responsibility and evolve toward perfection and a greater and fuller life, or shirk his responsibility, time alone can tell. Let us share the optimism of former Justice Holmes when he said, "I do not pin my dreams for the future to a country or even to my race. I think it probable that civilization somehow will last as long as I care to look ahead â€" perhaps with smaller numbers, but perhaps also bred to greatness and splendor by science. I think it not improbable that man, like the grub that prepares a chamber for the winged thing it never has seen but is to be â€" that man may have cosmic destinies that he does not understand. And so beyond the vision of battling races and an impoverished earth I catch a dreaming glimpse of peace."