346 RESPIRATION 



the quantities excreted daily. In a man not at work it can be estimated on 

 the basis of direct observations for twenty-four-hour periods at 0.5 g. per hour 

 per kilogram of body weight, which for a person of the average weight of 

 70 kg. would amount to 35 g. per hour and 840 g., or 427 1. per twenty-four 

 hours. At heavy physical labor the hourly output of C0 2 may rise to 169 g. 

 and higher; in complete bodily rest it falls to about 20 g. per hour (Fig. 134). 

 The intake of oxygen, like the output of carbon dioxide depends upon the 

 food, work, temperature, age, etc. With a respiratory quotient of 0.80 the 

 oxygen consumption corresponding to a carbon dioxide output of 427 1. per 

 day would be 534 1., or 764 g. According to the indirect determinations of 

 Pettenkofer and Voit, in the grown man fasting and at rest it amounts to 

 740-780 g., fasting and at work 1,070 g., on a moderate diet and at rest 

 700-900 g., on a moderate diet and at work 1,000 g., etc. By direct deter- 

 minations with the respiration apparatus of Hoppe-Seyler the oxygen absorp- 

 tion in a grown man on a mixed diet and not at work amounted to 559-586 g. 

 per twenty-four hours (Laves). In experiments of shorter duration Magnus- 

 Levy found the oxygen absorption in a fasting individual at complete rest 

 to be 17.5-19 g. per hour, which corresponds to a daily absorption of 428 

 to 456 g. 



