14 PHYSIOLOGY CHAP. 



1867 grms.,. we have the approximate amount of carbon dioxide 

 discharged =917 grms., whereas the oxygen absorbed was =720 

 grms. 



If the volumes of carbon dioxide discharged and oxygen 

 absorbed are calculated from these weights, the respiratory 

 quotient is as follows : 



This quotient of 0'92 is very nearly 1, which implies that 

 carbohydrates were chiefly consumed, these substances giving by 

 combustion a volume of carbon dioxide equal to the volume of 

 oxygen absorbed, that is, a quotient of 1. This quotient is much 

 higher than that given by the complete combustion of fats, which 

 is 0'71, from which it follows that little of the fat introduced as 

 food was burnt, and consequently all the carbon retained in the 

 organism was in the form of fat. 



If all the 41 grms. of carbon retained are represented by fat, 

 the subject of the experiment had stored up 55 grms. of fat. 

 Since his weight increased by 138 grms., there is an excess of 

 85 grms., which can only represent water retained. The balance 

 of water, on the other hand, shows that 2100 grms. of water were 

 taken and 2315 eliminated, i.e. 215 grms. more. We must, however, 

 take into account the fact that water is generated in the body 

 during combustion. The oxidation of the carbohydrates, protein, 

 and fat produced respectively 224, 54, and 30 grms. of water, a total 

 of 308 grms. If we take 215 grms. from this total, we find that 

 93 grms. of water are retained. The figure (93) resulting from 

 this calculation differs but little from that (85) arrived at above. 

 The difference falls within the limits of experimental error and 

 of the rounding of the figures customary when making the 

 calculation. 



Another typical example of investigation of exchange of 

 material, carried out with the utmost exactitude and for a period 

 of four days, is shown in the following table drawn up by Atwater 

 and Benedict. The subject was a man 34 years of age, and about 

 64 kgrms. in weight, and he kept as quiet as possible in a state 

 of repose for the four days. The table shows the daily average 

 of the intake and output with the exception of the oxygen 

 consumed : 



[TABLE 



