Les données et les inconnues du problème alimentaire. VIII.

The authors, having made extensive experimental contributions in this field in recent years, are well qualified to discuss the problems of nutrition. The subject of alimentation is outlined in great detail in the first volume; in fact, this introduction occupies 156 pages. A food is defined as a "substance, as a rule natural and complex, which, associated with other substances in proper proportions, is capable of assuring the regular cycle of life of an individual and the continuance of the species to which the individual belongs." This is quite evidently a vigorous attempt at framing a statement sufficiently broad to include such recently discovered substances as vitamin E, the fat-soluble factor necessary for successful reproduction. Nothing is presented about other definitions that have been offered. This is not a serious omission but rather one suggested by the detailed and elaborate organization of the material presented in the book. Approximately a