The author of this book is professor of pediatrics of the University of Chile. It is his conception that individual physiologic conditions existing in the germ plasm may affect the offspring. The first chapter deals with such known and acknowledged factors as achondroplasia, cretinism and congenital deformities. In the second chapter, the author, using the classification of Sigaud, shows how these types are inherited, with the different phases of their mixture. In the third chapter he deals with the development of dystrophies, debilities and prematurity, and in the final fourth chapter with functional alterations in the organism that are derived from constitutional anomalies, such as exudative diathesis, rickets, avitaminosis and similar deficiencies. This work is well written and profoundly interesting. The photographs are well reproduced, and the printing is excellent.