BASAL METABOLISM. 



117 



whose metabolism was determined practically every morning for several 

 months. (See tables 47 and 48.) The uniformity of the average 

 metabolism for the day throughout this extended period is striking, 

 to say the least, the variations in the metabolism being small. In 

 fact, these particular experiments have been cited as conclusive evi- 

 dence that when the base-line has once been fairly established it may, 

 with propriety, suffice as a common base-line for subsequent use. But 

 in physiological experimenting of this kind a subject is rarely so com- 

 pletely under control that he can be used daily for several weeks and 

 even months in experiments with a respiration apparatus. Such condi- 

 tions have never, we believe, been duplicated in experiments in which 

 the influence of the ingestion of food had been primarily considered. 



In studying a superimposed factor with a great increase in metab- 

 olism, such as that commonly occurring in severe muscular work experi- 

 ments, the use of a common base-line is open to the least objection, but 

 most factors have a less pronounced effect upon the metabolism than 

 severe muscular work. Even with so constant a metabolism as that 

 of M. A. M., it would be impossible to use an average basal value in 

 many experiments with him on the influence of the ingestion of food, for 

 the variations in the metabolism in the supposedly satisfactory collec- 

 tion of basal values were at times plus or minus 5 or 10 per cent, and the 

 total effect of many processes of digestion fall well within this limit. 



The constancy in the average metabolism shown in tables 37 to 45 

 confirm in practically every detail the general conclusions drawn by 

 Gigon 2 from the basal data obtained by him with the Sondn-Tigerstedt 



TABLE 47. Carbon dioxide produced at different times of day in, respiration experiments; 



subject M. A. M., in post-absorptive condition and lying on couch. (Values per minute.) 



Average age, 29 years. Average body-weight (naked), 66.0 kilograms. Height, 177 cm. 



J The experimental periods were usually 15 minutes in length and there was but one period in 



each half hour. 

 2 Gigon, Munch, med. Wochenschr., 1911, 58, p. 1343. 



