By means of a series of ingenious diagrams and sketches the author attempts to present a résumé of the present knowledge of endocrinology. The general style of this publication is sufficiently like that of a Mother Goose book to evoke a smile at first, but one soon realizes that this is no laughing matter at all and that the author has presented a sound, scholarly and immensely useful book of reference. However, it is unfortunate that many of the diagrams must be a little hypothetic, in view of the rapidly changing status of certain phases of the subject.