Previous numbers in this system of human biology have been reviewed from time to time in The Journal. The present volume is concerned with constitution, with particular references to the sexual system, the teeth, the special senses, the kidneys and the vegetative nervous system. The authors are men who have given detailed study to the subjects they discuss. More and more it becomes apparent from works of this kind that the treatment of human disorders without a thorough understanding of growth, development and constitution is not possible. The knowledge of the effects of the endocrine glands, while incomplete, is nevertheless already sufficient to be an important determining factor in the control of many unusual conditions. The medical curriculum is already overcrowded, but in the reorganization of the curriculum sooner or later some provision must be made for proper emphasis on constitutional background.