Heredity I.-Heredity II.-The inheritance of acquired characters.-The determination of sex.-Why do more boy babies die than girls?-The dominant sex.-Biology in Utopia.-The control of the life-cycle.-The meaning of death.-'Elixir vitae.-Birth control.-Thomas Henry Huxley and religion.-On the history of science.-Birds and the territorial system.-An hour's psychology.-Evolution and purpose.-The frog and biology.-The tadpole: a study in developmental physiology.