IS IT FORMED FROM PROTEIB? 



291 



Since the publication of Pfluger's criticism E. Voit, Cremer, and 

 Gruber have advanced evidence in favour of the proteid origin of 

 fat. Taking the ratio of N to C in the flesh fed as 1 : 3-29, E. Voit 

 obtained an onput of 30' 6 5 grm. C in three days, which is 

 equivalent to 69 grm. glycogen, i.e. much more than the animal 

 could be expected to have stored up in the time. Cats yield 1'5 

 8-5 grm. glycogen per kg. (Bohm and Hoffmann). The inference 

 drawn by Voit, therefore, was that fat was stored. 



Cremer fed a cat for eight days in the respiration chamber, 

 giving it 450 grm. lean meat per diem : the average daily excretion 

 of N was 13 grm. Taking the ratio N to C as 1 : 3*2, this amount of 

 meat gives 41'6 grm. C as the amount taken in the food, while only 

 34-3 grm. were excreted per diem. Thus 7-3 grm. were retained. In 

 three other experiments 12-6 per cent, to 17*0 per cent. C were 

 retained. Gruber fed two dogs on 1500 grm. lean meat, the N in the 

 faeces and urine were determined and the C0 2 output for five days. 

 The N to C ratio was taken as 1 : 3-28. The total retention of 



carbon was 



Calculated as Glycogen 

 C. (40 grm. C = 90 grm. Glycogen). 



Exper. 1 . 113-9 256-3 glycogen. 



2 . 195-9 441-0 



So much glycogen could not have been put on by dogs weighing about 

 20 kg., and so the carbon was assumed to be put on as fat. There 

 are possible sources of fallacy in these experiments. Firstly, 



