f 



ON THE BALANCE OF THE VITAL ECONOMY. 427 



10:7. The absorption of the oxygen is also found to diminish unequally, 

 beiii"- much less at the commencement of the period of inanition and towards 

 the close of life. The quantity of oxygen expired as carbonic acid also falls 

 (from 80 to To per cent.). On the whole a fasting animal loses daily 1 per 

 cent, of its body substance, calculated as free from water, of which 0.6 is al- 

 buminous and 0.4 fat. Bischoff and Voit have made similar series of re- 

 searches on a dog, after having previously in one experiment fed him well; 

 in a second, after having gradually diminished the amount of food; and in 

 others, after having given him an excessive supply of meat and fat. The 

 general conclusions at which they arrived were, that during inanition the 

 amount of consumption of the animal's own tissue was dependent upon its 

 size; since if it had been previously well fed, it lost more in a given time, 

 and if it had been badly fed it lost less; living in the latter case, as it were, 

 more economically. And further, the consumption was found to fluctuate 

 between the two chief factors of the body, the muscular tissue and the fat, 

 in such a manner that a very muscular animal consumed more flesh, and a 

 very fat animal more fat; which result is attributable in part to the presence 

 of a greater bulk or mass of the tissue, which is consequently more exposed 

 to the action of the oxygen absorbed, and undergoes a greater amount of 

 disintegration. In the experiment in which the animal had been previously 

 well fed, and with a mean weight of 70 Ibs., the proportion of nitrogen to 

 that of carbon eliminated was as 1 : 19; the proportion of nitrogen eliminated 



lerdiera for each 1 lb. of body weight being 2.1 grains, and of carbon 40 grains. 



n a second experiment, where the dog had previously been fed on progres- 

 sively diminishing quantities of meat, and weighed 70.7 Ibs., the proportion 

 of N to C was as 1 : 24, and there were eliminated for each 1 lb. of body 

 weight 1.68 grains of N and 40 grains of C. In a third experiment, where 

 the dog had been so abundantly fed that its mean weight throughout the 

 experiment was 85 Ibs., the proportion of N to C was as 1 : 16.3, the 

 quantity of N eliminated per diem to each 1 lb. of body weight being 1.54 

 grains, and 25.2 grains of C. Similar observations have been made by 

 Ranke 1 on himself; and the influence of diet in Man, in effecting a varia- 

 tion in the composition of the excretions, is well shown in the following table, 

 based on his experiments: 



Proportion of 



Nitrogen to Carbon Quantity of Nitro- Quantity of Carbon 



in the collective gen excreted per excrettd per diem 



excretions ot the diem for each 1 Hi. for each 1 lb. of 



Skin, Lungs, and of body weight, in body weight, in 



Kidneys. grains. grains. 



With mixed food, 1:12 1.817 457 



In inanition 1 : 17 1.000 17.82 



"With non-nitrogenous food, . . . 1 : 25 .788 19 5 



With excessive and exclusive meat | i-fi 867 528 



diet (4 Ibs.), .[ 



Ranke found in his experiments that Man required more carbon, i.e., more 

 fat or starch, in his food to supply the wants of his economy, than appeared 

 to be requisite in the Dog experimented on by Bischoff and Voit; and he 

 further remarks that the quantity of nitrogen appearing in the excreta bears 

 an inverse proportion to the carbon contained in the food: consequently, 

 when the fat or starchy constituents of the food are insufficient, the albu- 

 minous constituents of the body are drawn upon or are consumed to main- 

 tain the temperature. He found also 1. That the minimum quantity of 

 urea (containing nearly all the nitrogen) is discharged during hunger. 2. 



1 Mullet's Archiv, 1832, p. 335 et seq. 



