Referring to recent and earlier brilliant research on the etiology and treatment of rickets, Degkwitz describes his attempts to explain the development of rickets on the basis of early and recent observations of cell lipoids as chemical entities and as structural units of living protoplasm. After a discussion of lipoids and lipoid antagonisms, these compounds are discussed most interestingly from the point of view of all their properties in vivo and in vitro. The author concludes that he has failed to discover the mode of action of viosterol and the lipoidal building stones of cells, but feels comforted by the results of his investigations on the score of having thrown new light on lipoid actions. The book is of no immediate practical value to the pediatrician. To any one working in the field of lipoids it is a handbook of fact, containing an extensive bibliography.