PHYSIOLOGY: F. G. BENEDICT 
105 
From the groups of men and women it was possible to make selections 
of a number of individuals who had approximately the same height 
and weight; on this basis alone can an intelligent comparison be made. 
Eleven groups, with body weights varying from 67 kg. to 45 kg., 
were compared and it was found that the average heat-production of all 
eleven groups, computed on the basis of per kilogram of body weight, 
was 26.5 calories with men and 25.0 calories with women. The heat 
output of the men was greater in all but three of the eleven groups. 
Using again the computation on the basis of the heat production per 
square meter of body surface we found that the average for the eleven 
groups showed 819 calories per 24 hours for the men as compared with 
770 calories for the women. Of the eleven groups only two had lower 
values for the men than for the women. 
On the basis of the foregoing paper, giving the results of a study of 
athletes, we rigorously excluded athletes from these comparisons, and 
hence we are dealing here with non-athletic men and women of the 
same height and the same weight. It is thus reasonable to suppose that 
the actual body surface of the different groups must have been very 
nearly the same, and it is not logical to assiune that the larger heat pro- 
duction noted with the men was due to a disproportion between the body 
measurements and the body surface. We beHeve that these data 
show a basal metaboHsm for men some 5 or 6% greater than for women 
of similar height and weight, and that this increase is due to the fact 
that in all probability the women, particularly in those groups with the 
greater body weight, had a much larger proportion of subcutaneous fat 
than did the men, thus indicating a consequent smaller proportion of 
active protoplasmic tissue. 
The detailed report of this investigation has been transmitted to the 
Journal of Biological Chemistry. 
THE FACTORS AFFECTING NORMAL BASAL METABOLISM 
By Francis G. Benedict 
NUTRITION LABORATORY. CARNEGIE INSTITUTION OF WASHINGTON 
Presented to the Academy, January 13, 1915 
Although it is well known that the basal normal metabolism of indi- 
viduals varies considerably, the exact cause for these variations is not 
known. For many years physiologists have beheved that the heat 
production of a Kving body is proportional to the surface area. This 
most helpful hypothesis served to bring order out of chaos in the earlier 
