During the past twenty or thirty years attempts have been made to study every morbid condition from the point of view of the individual characteristics of the patient. Each study has required some criterion or standard of evaluation of the constitutional status, and while a search was being made for this criterion, attention was largely focused on the morphologic peculiarities of the body and the anatomic correlation of its parts. Thus experiments were undertaken to determine the normal constitutional types of the human body. As each investigation was based on a different principle, a great number of schemes were proposed, each of which divides mankind into three or four main constitutional types. The most popular schemes were those devised by Sigeaud, Viola and Kretschmer. None of them has been universally adopted, but there is much similarity between the types as outlined by these different investigators. It must be emphasized that