536 TISSUES OF THE CONNECTIVE SUBSTANCES. 



has arrived at the conclusion that the assumption as to the formation 

 of fat from proteins finds no support in these experiments. 



In opposition to these objections, E. VOIT and M. CREMER have made 

 new feeding experiments to show the formation of fat from proteins, but 

 the proof of these recent investigations has been disputed by PFLUGER. 

 On feeding a dog on meat poor in fat (containing a known quantity of 

 ether extractives, glycogen, nitrogen, water, and ash), KUMAGAWA l 

 could not prove the formation of fat from protein. According to him 

 the animal body under normal conditions has not the power of forming 

 fat from protein. 



Several French investigators, especially CHAUVEAU, GAUTIER, and 

 KAUFMANN, 2 consider the formation of fat from proteins as positively 

 proven. KAUFMANN has recently substantiated this view by a method 

 which will be spoken of in detail in Chapter XVIII, in which he studied 

 the nitrogen elimination and the respiratory gas exchange in conjunction 

 with the simultaneous formation of heat. 



As we are agreed that carbohydrates and glycogen, as well as sugar, 

 can be formed from proteins, the fact cannot be denied that possibly 

 an indirect formation of fat from proteins, with a carbohydrate as an 

 intermediate step, can take place. The possibility of a direct fat for- 

 mation from proteins without the carbohydrate as intermediary must 

 also be generally admitted, although such a formation has not been 

 conclusively proven. 



According to CHAUVEAU and KAUFMANN, in the direct formation of 

 fat from proteins, the fat is formed besides urea, carbon dioxide, and 

 water, as an intermediary product in the oxidation of the proteins, while 

 GAUTIER considers the formation of fat from proteins as a cleavage 

 without the taking up of oxygen. If fat is formed from protein in the 

 animal body, then such formation is not a splitting off of fat from the 

 proteins, but rather a synthesis from primarily formed cleavage products 

 of proteins which are poor in carbon. 



The formation of fat from carbohydrates in the animal body was 

 first suggested by LIEBIG. This was combated for some time, and until 

 lately it was the general opinion that a direct formation of fat from 

 carbohydrates not only had not been proven, but also -that it was 

 improbable. The undoubtedly great influence of the carbohydrates on 

 the formation of fat as observed and proven by LIEBIG was explained 

 by the statement that the carbohydrates were consumed instead of 

 the absorbed fat or that derived from the proteins, hence they have a 

 sparing action on the fat. By means of a series of nutrition experiments 



1 See Rosenfeld, Fettbildung, Ergebnisse der Physiologic, 1, Abt. 1. 



2 Kaufmann, Arch, de physiol., (5) 8, where the works of Chauveau and Gautier 

 are cited. 



