RESPIRATION. 641 



periments. If we reckon the animal heat evolved to be 100, t he 

 quantity of it due to the consumption of oxygen varies in the dif- 

 ferent experiments from 93. 1 to 74.5. This variation will be best 

 understood if we arrange the experiments in the form of a table : 



Heat evolved. ^ 



Rabbit, . . 100 93. 1 



Six small rabbits, . . 100 83-58 



Three male guinea pigs, . 100 90 -72 



A dog, five years old, . 100 81-94 



A dog, eight months old, . 100 76-40 



Two dogs, six weeks old, . 100 74-57 



A male cat, . 100 81 -56 



Three adult male pigeons, . 100 79 -87 



An adult Virginian duck, 100 77 -11 



Mean, . . 100 82 



To be able to compare the breathing of different animals toge- 

 ther, as far as the consumption of oxygen is concerned, it would 

 be necessary to know the weight of the different animals sub- 

 jected to experiment. This, unfortunately, Despretz has ne- 

 glected to determine. 



Nearly about the time (1823) that Despretz was occupied with 

 the experiments just detailed, a similar set of experiments was 

 made by M. Dulong. His method of proceeding was nearly si- 

 milar to that of Despretz. It will, therefore, be sufficient to state 

 here the results which he obtained. 



His experiments were made upon six kinds of animals, name- 

 ly, the dog, the cat, the hawk, the cabiai, the rabbit, and the pi- 

 geon ; and each was several times repeated. 



The volume of oxygen consumed by the respiration of the dog, 

 the cat, and the hawk was a third more than that of the carbonic! 

 acid gas formed ; and only one-tenth more in the rabbit, the ca- 

 biai, and the pigeon. Dulong conceives that this difference is 

 connected with the different kind of food on which these animals live. 

 More azote is given out during the respiration of herbivorous 

 animals than of carnivorous. In the former the bulk of the air 

 expired generally exceeds that of the air inspired. 



In carnivorous animals the heat due to the formation of car- 

 bonic acid gas amounts to 0*49 to 0*55 of the whole heat evolved ; 

 in frugivorous animals to from 0*65 to 0*75. 



If we suppose with Lavoisier and Despretz that the portion of 



s s 



