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 vitæ."--Birth control.--Thomas Henry Huxley and religion.--On the history of science.--Birds and the territorial system.--An hours's psychology.--Evolution and purpose.--The frog and biology.--The tadpole: a study in developmental physiology.