172 Metabolism of Healthy Man. 



The results of the carbon-dioxide excretion during sleep are, as has been 

 pointed out, comparable with those made with the Zuntz-Geppert respiration 

 apparatus during complete muscular relaxation when lying on a couch. The 

 results obtained in the experiments in which the subjects were awake sitting 

 up in a chair are obviously considerably higher, but, on the other hand, they 

 more truly represent the carbon-dioxide production of a subject sitting awake 

 and resting quietly. The results are presented in table 69. The largest 

 amount measured was with the subject J. W. H., 39.6 grams per hour, or 

 336 c. c. per minute. The smallest amount was that with the subject H. R. D., 

 25.9 grams per hour or 220 c. c. per minute. This table indicates that the 

 average carbon-dioxide excretion per hour for a normal man when sitting and 

 resting is 33.3 grams of carbon dioxide per hour or 282 c. c. per minute. As 

 has been pointed out, these values have no relation whatever to the body-weight 

 of the individual, and for purposes of comparison it is more advantageous and 

 physiologically more correct to compute the values on the basis of per kilogram 

 of body-weight per hour and per square meter of body-surface. 



Per kilogram of body-iueight. Dividing the total hourly excretion by the 

 body-weight, we have the carbon dioxide produced per kilogram of body-weight 

 per hour. On this basis the largest amount is with the subject 0. F. T., or 

 0.672 gram per hour; the smallest is with the subject H. C. K., or 0.409 gram 

 per hour. The average of all the subjects is 0.521 gram per hour. Using the 

 other method of expressing the amount per kilogram of body-weight, namely, 

 in cubic centimeters per minute, we have variations from 5.70 c. c. with O. F. T. 

 to 3.47 c. c. per minute with H. C. K. The average for all the subjects was 

 4.42 c. c. per kilogram per minute. 



Per square meter of body-surface. The largest amount expressed in these 

 terms is likewise found with the subject O. F. T., or 21 grams per square meter 

 of body-surface per hour. The smallest amount was found with A. H. M., 

 i. e., 13.6 grams per hour. The average of all subjects was 16.9 grams per hour. 

 Expressing the results in terms of cubic centimeters per minute per square 

 meter of body-surface, we have 178 c. c. with 0. F. T. and 116 c. c. with 

 A. H. M., the average of all subjects being 143 c. c. per square meter per minute. 



RATIO OF CARBON-DIOXIDE ELIMINATION DURING SLEEP TO THAT 



DURINOx WAKING HOURS. 



While all of the experiments here reported are distinctly rest experiments, 

 with a minimum amount of muscular work, nevertheless, there is a noticeable 

 difference between the muscular activity when the subjects are lying quietly 

 in bed covered and sound asleep, and when they are sitting in a chair turning 

 over the pages of a book or moving about the chamber attending to food, dishes, 

 etc. There is a marked difference in the muscular activity between the day 

 and the night, and consequently the carbon-dioxide production during these 

 periods varies considerably. For the subjects with which we have experiments 



