THE HISTORY OF FAT IN THE BODY 887 



they probably wander chiefly as neutral fats, to be rehydrolysed for 

 their passage into the cells of the body, which they may enter either 

 in the form of soaps or possibly as fatty acids dissolved in some of 

 the constituents of protoplasm. 



FORMATION OF FAT FROM CARBOHYDRATES. It has long 

 been the experience of farmers that animals might be fattened on 

 a diet in which carbohydrates predominate. The chemical difficulty 

 involved in the transformation of carbohydrates into fats has 

 often led to a doubting attitude on the part of chemists towards this 

 transformation. Voit put forward the view that when fats are formed 

 in the body as a result of an excessive carbohydrate diet, they are 

 formed, not directly by a transformation of carbohydrate, but from 

 the proteins of the food, the role of the carbohydrates of the food being 

 simply to protect the proteins from disintegration and oxidation, so 

 that the whole of their carbon can be utilised for the formation of fat. 



Definite evidence has, however, been brought forward, especially 

 by Lawes and Gilbert, for the transformation of carbohydrates into 

 fats. In these experiments two young pigs, ten 'weeks old, of the 

 same litter, with approximately equal weights, were taken. One was 

 killed and the fat and total nitrogen in the body estimated. From the 

 amount of nitrogen the maximum possible quantity of proteins present 

 was calculated. The second was fed on barley for four months. The 

 barley was measured and analysed, as well as the amount of undigested 

 fat and protein that passed through the animal. At the end of the 

 four months the second animal was killed and analysed. It was found 

 that the animal contained l - 56 kilos more protein and 8'6 kilos more 

 fat. It had taken up with the food 7 '49 kilos more protein and 

 O66 kilo fat. If we subtract the protein added to the body (T56) 

 from that taken up with the food (7'49) there is a remainder of 5'93 

 kilos which might possibly have given rise to fat. But 7'9 kilos of 

 fat had been added in the body a far larger amount than could 

 possibly have arisen from the maximum amount of protein left over 

 for the purpose. At least 5 kilos of fat in this experiment must have 

 been derived from the direct conversion of the carbohydrates of the 

 food. We must conclude that fat can be formed directly from carbo- 

 hydrates, although how and where this conversion takes place is at 

 present quite unknown. The fats formed on a carbohydrate diet are 

 deposited chiefly in the subcutaneous tissue. For the reasons already 

 given the liver is found free from fat under these conditions. In the fat 

 formed from carbohydrate the two saturated acids, palmitic and stearic 

 acid, predominate. On this account the fat has a firm consistency and 

 a high melting-point. The fats of low melting-point, such as olein, 

 are absorbed more readily from the intestine than those of high 

 melting-point. Where the fat of the body is chiefly derived from the 



