Hormones and Heredity It is a history book. Probably the majority of those who have given any thought at all to the subject if asked how the evolution of animal life from the lowest living organism to man has been brought about would reply By natural selection, meaning that process by which variations beneficial to the individual result in its sur- vival, while members of the same species who lack these varia- tions tend to perish. To-day, however, although there is no dispute that Darwin by his theory of natural selection immonsely advanced our understanding of the problems of evolution, natural selection is regarded as only a partial explanation of the observed phenomena and much thought and experiment are being devoted to their further elucidation. Among students of the subject the author of this volume has, by his suggestive writings, taken a prominent place, and the views here pro- pounded will no doubt be carefully considered by his fellow investigators. Who will perhaps be reminded by many passages of Alice in Wonderland and the Duchess's simplification of the words 'Be what you would seem to be', a simplification extending to four printed lines. But many interesting scientific facts are brought out in the presentation of the writer's argument which in them- selves will repay the reader for his perseverance. We feel that Mr. Cunningham has made a very useful contribution to the current conceptions of heredity.