FORMATION OF FATS. 561 



poisoning, that we cannot consider the formation of fat as conclusively 

 proved. The investigations of LEBEDEFF, ATHANASIU, TAYLOR, SCHWALBE 

 and others, have shown that probably no new formation of fat from 

 protein took place, but rather a fat migration and that this is .actually 

 the case has been especially shown by ROSENFELD and recently by SHI- 

 BATA 1 in a conclusive manner. 



Another more direct proof of the formation of fat from proteins 

 has been given by HOFMANN. He experimented with fly-maggots. 

 A number of these were killed and the quantity of fat determined. The 

 remainder were allowed to develop in blood whose proportion of fat 

 had been previously determined, and after a certain time they were killed 

 and analyzed. He found in them from seven to eleven times as much 

 fat as was contained in the maggots first analyzed and the blood taken 

 together. PFLUGER 2 has made the objection that a considerable number 

 of lower fungi develop in the blood under these conditions, in whose 

 cell-body fats and carbohydrates are formed from the different con- 

 stituents of the blood and their decomposition products, and that these 

 serve as food for the maggots. 



WEiNLAND 3 has observed the formation of higher non- volatile fatty 

 acids in the Calliphora larvae when they were rubbed to a homogeneous 

 paste after the addition of Witte's peptone. This experiment shows a 

 formation of fat from protein, but cannot be considered as quite con- 

 clusive. 



As a more convincing proof of fat formation from proteins, the 

 investigations of PETTENKOFER and VOIT are often quoted. These 

 investigators fed dogs with large quantities of meat containing the least 

 possible proportion of fat, and found all of the nitrogen in the excreta, 

 but only a part of the carbon. As an explanation of these conditions 

 it has been assumed that the protein of the organisms splits into a 

 nitrogenized and a non-nitrogenized part, the former changing into the 

 nitrogenized final product, urea, and like products, and the other part, 

 on the contrary, being retained in the organism as fat (PETTENKOFER 

 and VOIT). 



PFLUGER has arrived at the following conclusion by an exhaustive 

 criticism of PETTENKOFER and VOIT'S experiments and a careful recal- 

 culation of their balance-sheet; that these very meritorious investiga- 



1 Bauer, Zeitschr. f. Biologie, 7; Leo, Zeitschr. f. physiol. Chem., 9; Polimanti, 

 Pfliiger's Arch., 70; Pfliiger, ibid., 51 (literature on the formation of fat from protein) 

 and 71; Athanasiu, ibid., 74; Taylor, Journ. Exp. Medicine, 4; see also footnote 2, 

 p. 384; Shibata,Bioch. Zeitschr., 37, which contains the literature; Rosenfeld, Ergebn. 

 d. Physiol., 1. 



2 See Rosenfeld, Fettbildung, Ergebnisse der Physiologie, 1, Abt. 1. 



3 Zeitschr. f. Biol., 51 and 52. 



