J. A. Harris and F. G. Benedict 263 



If the metabolism of the individual changes from time to time 

 rrespective of changes in bodily dimensions it would seem reason- 

 ible to presume that these changes would be greater for more 

 videly separated periods. Thus the observations made on a single 

 lay can be reasonably regarded as based upon a subject in prac- 

 ically stationary physical and physiological conditions. Those 

 aade at widely separated dates more probably represent the indi- 

 ddual in somewhat different physiological states. Thus while 

 he active protoplasmic mass is probably essentially identical in 

 he two cases (if the periods are not too widely separated) the 

 inknown stimulus to metabolic activity may differ to a consid- 

 rable extent from one period to the other. 



As a measure of variation of the metabolism of the individual 

 ve have adopted the standard deviation 10 of the measurements of 

 ach subject. As a measure of time covered by the observation 

 re have taken the actual number of days, including the days 

 pon which the measurements were made, i.e. (Tz + 1) TI, 

 /here TI and T z are the times of the first and last measurements, 

 &quot;hus if the metabolism of an individual were measured on July 



and 2 the range would be 2 days. If three observations were 

 lade, one on July 1, one on July 10, and one on September 3 of 

 he same year, the range would be 65 days. Correlating between 

 le range in days and the standard deviation of total calories per 

 4 hours we have for 101 individuals 



r = +0.276 0.062, -- = 4.45 

 L T 



The coefficient measuring the relationship between range in 

 ays and the standard deviation of calories per square meter as 

 itimated by the Du Bois height-weight chart, which will be the, 

 nly approximation to the body surface used, is 



r = +0.2540.063, -- = 4.03 



E r 



The correction between the range of days over which the experi- 

 ients extended and the standard deviation of calories per kilo of 

 ody weight is 



r = +0.248 0.063, - = 3.94 

 E r 



10 The coefficient of variation might have been used with equal propriety. 



