394 



Carhon-dioxide Excretion in Man 



[April 



exerted through the nervous and circulatory Systems tending to 

 increase the readiness of metabolism; if such were the case then a 

 Variation in barometric height should be accompanied by a Variation, 

 in the same sense, in the rate of excretion of carbon dioxide. 



Plan of the experiments. It seemed that a series of experi- 

 ments carried out for a month on three healthy subjects might throw 

 light on this question, and also give interesting results as regards the 

 effect of other conditions on the rate of carbon dioxide excretion. 

 A series of respiration experiments was planned, accordingly, for 

 three subjects, A and B, students in the University of Michigan, 

 and the writer, C. A and B were 24 and 22 years of age re- 

 spectively, and weighed, without clothing, 158 and 159/^ pounds. 

 C was 46 years of age and weighed, exclusive of clothing, 148 

 pounds. Each subject was to live his regulär daily life except that 

 no vigorous muscular exercise was to be engaged in immediately 

 preceding any experiment and that nothing whatever was to be 

 eaten between meals. The plan of work is indicated in the ap- 

 pended summary, where the data for the third part of each experi- 

 ment are placed below those for the first and second : 



The routine of work was as follows : The subjects rose at 6 

 o'clock, reaching the laboratory at about 6:35. A reclined upon a 

 couch at 6 :45 in preparation for the first experiment. B and C 

 prepared all the apparatus, making the initial calibration of the 

 balance, weighing the guard tubes, reading and recording the 

 barometric height, the outdoor and room temperature, etc. In order 

 to enable the experimenter to judge the better as to the physical 



