164 Metabolism of Healthy Man. 



Using the mouthpiece with the Zuntz-Geppert respiration apparatus, Magnus- 

 Levy 1 studied the respiratory exchange of a man (56.2 kilos) without food 

 for a number of hours during the day. From 9 h 45 m p. m. to 10 h 30 m p. m., 

 when the notes record that the man was asleep, the average carbon-dioxide 

 production per minute was 147.1 c. c. From 1 a. m. to l h 40 m a. m., when the 

 subject was in part asleep, the carbon-dioxide production averaged 152.5 c. c. 

 per minute in 3 experiments. At 4 h 16 m a. m. and 4 h 39 m a. m., when the 

 subject was reported as being but partly asleep, the carbon-dioxide excretion 

 was very much larger, averaging 171.4 c. c. 



In this laboratory it has been found extremely difficult to secure tight 

 closure with the use of a mouthpiece, unless the subject gives particular atten- 

 tion to holding the mouthpiece in the proper position. Almost invariably when 

 the subject is asleep the muscles of the face and jaw relax and there may be 

 distinct opportunity for leakage of air around the mouthpiece ; hence one must 

 look askance at the results obtained during sleep with the mouthpiece or mask. 

 On the other hand, when the subject is inclosed in an air-tight chamber with 

 normal respiration, the error incidental to the measurement of the carbon- 

 dioxide production during sleep does not result from imperfect closure of the 

 mouth, and the co-operation of the subject himself is not needed for successful 

 experiments. 



In several experiments made with his respiration chamber, Scharling 2 had 

 periods when the subjects were asleep, and the analyses were so made that the 

 carbon-dioxide production during the sleeping periods could be observed with 

 reasonable accuracy. From the results of these experiments, Scharling has 

 concluded that with one subject weighing 65.5 kilos and 35 years of age, the 

 carbon-dioxide production during sleep was 22.79 grams. With another subject 

 16 years of age and weighing 57.7 kilos, the carbon-dioxide during sleep was 26 

 grams. With another subject, 28 years of age and weighing 82 kilos, in 2 pe- 

 riods the carbon-dioxide production yielded 27.9 and 31.4 grams respectively. 



Pettenkofer and Voit, 3 in an extensive series of experiments, separated the 

 day and night periods, but the night was not a true sleeping period. They 

 report that at night the subject lay in bed without eating any food and slept 

 for 6 hours, so that the muscular exercise incidental to sitting in a chair and 

 taking food was absent, While, therefore, the results they report are not, 

 strictly speaking, obtained during sleep, they may be used for comparison. In 

 10 rest experiments during which the carbon-dioxide production was studied 

 during the night period, the amounts per hour were as follows: 26, 26.3, 31.6, 

 33.7, 33.6, 35.2, 36.8, 27.6, 37.6, and 24.9 grams, respectively. All but the last 

 experiment were made with the same subject, whose body-weight was approxi- 

 mately 70 kilos. 



1 Magnus-Levy, Archiv f. d. ges. Physiol., 1894, 55, p. 35. 



2 Scharling, loc. cit. 



! Pettenkofer and Voit, Zeitschr. f. Biol., 1866, 2, p. 550. 



