THE ABSOLUTE AMOUNT OF RESPIRATORY EXCHANGE 345 



and D'Arsonval on the basis of numerous experiments had answered the 

 question in the affirmative. Their statements were put to the test by several 

 other authors, but by most of them without results. Formanek, however, 

 proved by exact methods that the poisonous effects observed by the above- 

 named authors on confined animals came in fact only from ammonia set free 

 from the solid and fluid excretions of the animal employed. 



Since the carbon dioxide in the air may rise to four or five per cent and 

 higher without exercising any harmful effects, we may conclude that the indis- 

 position which results from long confinement in badly ventilated or overcrowded 

 rooms is due, not to the influence of any poisonous constituents of the expired 

 air, but to other circumstances e. g., higher temperature, higher humidity, 

 gaseous substances coming from the intestine or from an unclean skin, etc. It 

 is assumed of course that the ventilation is not so bad that carbon dioxide accu- 

 mulates in too large quantities. 



4. THE ABSOLUTE AMOUNT OF RESPIRATORY EXCHANGE 



In the section on the nutrition of man (page 137) will be found fuller 

 information bearing on this subject. Here we must limit the discussion to 



6 8 10 12 2 4 6 8 10 12 2 4 6 

 p.m. a.m. p.m. 



FIG. 136. The elimination of carbon dioxide, in two-hour periods, by an eleven-year-old boy. 

 He slept between 10:30 P.M. and 8 A.M. 



some facts concerning the variations in the normal output of carbon dioxide 

 (Figs. 134, 135, and 136) estimated for two-hour periods. 



In view of the many circumstances which affect the amount of metabolism 

 and therefore the output of C0 2 , it is impossible to specify in a few figures 



