A HISTOEY OF METABOLISM 



41 



reported by Dulong is impossible and that Liebig had pointed out [p. 40] 

 that when one considered the loss of nitrogen in the urine and feces, an 

 animal expiring in addition the amount of nitrogen found by Dulong 

 would thus in a few days liberate all the nitrogen contained in the organic 

 material of its own body. They also state that the respiration cannot 

 contain more than extremely small quantities of ammonia.) 



4. ... The alternating elimination and absorption of nitrogen found 

 in the'same animal under various conditions is favorable to the opinions 



Fig. 6. The closed circuit apparatus of Regnault and Reiset. From "Annales de 

 Chimie et 'de Physique," Series 3, Vol. XXVI, PI. III. Water rising in the glass recep- 

 tacle drives oxygen into the glass bell jar. A pump alternately raises and lowers two 

 cylinders. The lower cylinder fills with alkali at the expense of the upper one, and 

 this movement 'of the liquid forces air from one cylinder into the bell jar and draws 

 a corresponding amount from the bell jar into the other cylinder.* 



of Edwards, who believes that an elimination and an absorption of nitro- 

 gen constantly takes place during respiration, and what one finds is the 

 resultant of these two contrary processes. 



5. The relation between the quantity of oxygen exhaled as carbon 

 dioxid and the quantity of total oxygen consumed appears to depend more 

 on the nature of the food than on the species of the animal. This ratio is 

 higher in the animals which live upon grain and in them it may exceed 

 unity. When they are given meat, the ratio is less and varies between 

 0.62 and 0.80. Upon a diet of legumes the ratio is between that found 

 after giving meat and that after giving bread. 



6. This ratio is nearly constant in animals of the same race, such as 

 dogs when they are given the same diet. 



