EXCHANGE OF MATERIAL. 459 



grins, greater on the day of the transfusion than on the following 

 day. According to these experiments, the proteids of the blood - 

 corpuscles, which are considered as tissue-proteids, are less easily 

 metabolized than digested blood-proteids or the proteids of the 

 blood-serum, and therefore these experiments confirm VOIT'S 

 views. 



It has been stated above that other foods may decrease the 

 destruction of proteids. Gelatine is such a food. Gelatine and the 

 gelatine-formers do not seem to be converted into proteid in the 

 body, and this last cannot be entirely replaced by gelatine in the 

 food. For example, if a dog is fed on gelatine and fat, its body 

 sustains a loss of proteids even when the quantity of gelatine is so 

 large that the animal, with an amount of fat and meat containing 

 just the same quantity of nitrogen as the gelatine in question, may 

 remain in nitrogenous equilibrium. On the contrary, gelatine, as 

 VOIT, PAJ^UM and OEBUM have shown, has a great value as a means 

 of sparing the proteids, and, according to VOIT, it may decrease the 

 decomposition of proteids to a still greater extent than fats and 

 carbohydrates. This is apparent from the following summary of 

 VOIT'S experiments on a dog : 



TABLE VI. 



Food per Day. Flesh. 



Meat. Gelatine. Fat. Sugar. Decomposed. On the Body. 



400 200 450 - 50 



400 250 439 - 39 



400 200 256 -f 44 



This ability of gelatine to spare the proteids is explained by 

 VOIT by the statement that the gelatine is decomposed instead of a 

 part of the circulating proteids, whereby a part of this last may be 

 organized. 



Gelatine may also decrease somewhat the consumption of fat, 

 although it is of less value in this respect than the carbohydrates. 



The question of nutritive value of peptones stands in close rela- 

 tion to the nutritive value of the proteids and gelatine. The early 

 investigations made by MALY, PLOS'Z and GYERGYAY, and ADAM- 

 KIEWIC'Z have led to the conclusion that an animal with food which 



