ORIGIN OF FAT OUT OF CARBOHYDRATE 299 



Nerve degeneration is the only authenticated example of a 

 proteid-contairiing substance yielding fat on decomposition. But 

 in this case the fat does not come from the proteid, but from the 

 lecithin moiety of protogon. 



The Weigert stain depends on the existence of protogon, the 

 Marchi stain on the setting free of oleic acid by the decomposition 

 of lecithin which follows the disruption of the protogon molecules. 

 The lecithin breaks down into phosphoric acid, fatty acids, and cholin. 

 Both the phosphorus and total fat content of the degenerating nerve 

 decrease, and the cholin passes into the blood, and may, it is said, 

 be detected therein ; but this is a disputed matter (Halliburton and 

 Mott). 



ORIGIN OF FAT OUT OF CARBOHYDRATE 



Laws and Gilbert, feeding swine on meal, found one pig (com- 

 pared with another of the same litter and weight) gained 55'5 Ibs. 

 of fat, while the food contained only 13-7 Ibs. Reckoning that the 

 whole of this food fat was put on, that the whole of the nitrogen 

 in the food was in the form of proteid, and that the whole of the 

 non-nitrogenous moiety of this proteid went to form fat, the total 

 comes out as insufficient to cover the fat put on. Therefore, fat 

 must have been formed from carbohydrate. Example : 



Lbs. 



Fat put on 71 '2 



Fat in food . 12 '4 



Fat produced . . . .58-8 



Proteid consumed . . . .64 



Proteid put on . . . . 6-5 



Available for fat . . . 57-5 



Carbon in fat put on . . 45' 3 



Carbon in available proteid (deducting ) 

 the carbon excreted as urea) . J 



Difference 17'9 



Swine are especially suitable for these researches, as they eat 

 a large amount of digestible food, pass a relatively small amount 

 of excreta, and put on fat rapidly. 



