The anthropometric studies that have been made in various diseases, such as tuberculosis,1 allergy and poliomyelitis,2 may be considered an indirect approach toward correlating body build with susceptibility and resistance to disease. However, not until there was some means of measuring an immune substance could immunity be subjected to anthropometric studies and the results of these studies, in turn, correlated with body build.
The diphtheria antitoxin in human serum is at present the only readily measurable immune substance. The antitoxin does not occur in measurable amounts in the blood of most children unless, or until, its production is stimulated by administration of diphtheria toxin or toxoid. A study of the antitoxin response to such stimulation has been previously reported in one cross section of the child population.3 The diphtheria antitoxin content of the blood serum was determined by the method of Jensen.4 The distribution of the