Studies of Human Organ System Function 75 



response to a standard exercise (Master and Oppenheimer, 

 1929) was ostensibly designed to disclose coronary arterio- 

 sclerosis in individuals with equivocal or no clinical evidences 

 of cardiac disease and in whom the electrocardiogram at rest 

 was normal. Agewise differences in the normal electrocardio- 

 graphic response to exercise have been reported by our 

 laboratory (Silver and Landowne, 1953), as well as by others 



none 



slight—* 



moderate 



marked-* 

 extreme^ 



all ages 



Fig. 1. Gross morphological total and agewise incidence of coronary 

 sclerosis, graded as to severity and expressed as percentage of the 

 corresponding age group. Data from over 3,000 consecutive male 

 autopsies reported by Willius, Smith and Sprague (1933). The 

 number of cases in each age group is indicated at top of the column. 



(Master, Friedman and Dack, 1942; Simonson and Keys, 

 1956). Although there may have been important differences 

 in the manner and effectiveness of selection of these "normals", 

 it would have to be admitted that they do not represent 

 "pure" normals, but are carefully selected subjects in whom, 

 statistically, coronary sclerosis is present with increasing 

 agewise incidence and severity. To have obtained a lesser 

 contaminating incidence of disease, one would need to have 

 known at least the information which was supposed to result 



