Three chapters from the author's larger Principles of Biochemistry are here reprinted in the form of a convenient volume. It is unfortunate that some information is presented without bibliographic references. There are also occasional statements of dubious importance; for example, it is said (page 19) that "corn silk extract has long enjoyed a reputation of value in treating obstinate cases of cystitis. Whether its use for this purpose depends upon its vitamin B1 content is, however, undetermined." The chapter on mineral metabolism is inadequate, even for an elementary presentation. The chapter on hormones is brief and might be useful as an introduction to the chemistry and physiology of the subject.