A HISTORY OF METABOLISM 35 



The modern calculation would be: 



O 2 CO 2 R. Q. Calories Calories 



indirect direct 



liters liters 

 3.30 2.59 0.78 15.86 14.68 



Or 8 per cent too much calculated heat instead of 11 per cent too 

 little. 



The conclusions of Despretz were : 



1. That the respiration is the principal cause of the development of 

 animal heat ; that assimilation, movement of the blood, friction in different 

 parts, can easily produce the small residual amount. 



2. Although oxygen is employed in forming carbonic acid, a certain 

 quantity, sometimes considerable in amount, disappears; it is generally 

 thought that it is used in the combustion of hydrogen. 



3. There is an exhalation of nitrogen in the respiration of both 

 carnivorous and herbivorous animals. 



The following animals were used : Ducks, chickens, cocks, young and 

 old pigeons, gulls, buzzards, owls, magpies, dogs, cats, rabbits and guinea- 

 pigs. 



Dulong (1785-1838) presented the second paper in competition for 

 the prize of the Academy, of which a resume follows : 



The author, who is both physicist and chemist, proposes to determine 

 if the quantity of oxygen intake is sufficient (in health) to repair the 

 heat loss by animals under natural conditions of life; in other words, 

 whether animal heat is entirely due to combustion which takes place 

 within the animal through respiration. 



He calls attention to the fact that Lavoisier used two different guinea- 

 pigs, one in the calorimeter and another for the determination of the 

 gaseous exchange. He uses the water calorimeter of Rumford. The 

 temperature of the water is the same as that of surrounding air at the 

 start ; at the end, higher. The animals can move at will. Cat, dog, kestrel, 

 capibara (water-hog), rabbit, and pigeon are used. He finds that in 

 the cat, dog and kestrel the volume of oxygen inspired is one-third more 

 than that of the carbonic acid expired, whereas in rabbits, capibara and 

 pigeons the oxygen is only one-tenth more than the carbonic acid. There- 

 fore he thinks this difference is due to food or to a difference of animal 

 organization through food. He finds that nitrogen is exhaled. The heat 

 from carbonic acid in carnivora is 49 to 55 per cent of the total heat 

 measured; in herbivora, 65 to 75 per cent. Calculated inclusive of the 

 heat produced from the oxidation of hydrogen, it equaled 69 to 80 per 

 cent. The experiments were repeated many times. 



One source of error in the calculations of Despretz and of Dulong 



