THE HISTORY OF FAT IN THE BODY 891 



not justified by Voit's results, and were really based on the fact 

 that too high a figure had been assumed for the carbon of the meat. 

 Whereas Voit found that the animal had laid on 56 grm. of fat during 

 one day of the experiment, a recalculation of the same results by 

 Pfliiger shows that the animal could not have put on more than 

 3-9 grm. of fat, an amount which might quite well be accounted 

 for by the fat and glycogen present in the meat. Pfliiger has shown 

 moreover that an animal may be fed for weeks on the leanest meat 

 that it is possible to procure, in any quantities, without putting on 

 any fat at all, and, as we have seen, increasing the ration of protein 

 increases simply the nitrogenous and general metabolism of the body. 



Although therefore we must assume that the healthy body does 

 not normally form fat from protein, there are certain pathological 

 conditions which seem at first to tell in favour of such a conversion. 

 Thus during certain diseases, such as diphtheria, pernicious anaemia, 

 and as the result of poisoning by phosphorus, the majority of the 

 organs of the body undergo acute fatty degeneration. The liver 

 may be enlarged and all its cells are studded with fat granules which 

 are apparently formed by a change in the protoplasm of the cells. 

 This change was long interpreted as due to a direct conversion of 

 protein into fat. More exact analyses have shown that during fatty 

 degeneration the total fat in the body is not increased. Thus one 

 observer took 124 pairs of frogs and poisoned one of each pair with 

 phosphorus. The animals were then killed, and the whole of them 

 analysed. The difference in the content of fat between the poisoned 

 and unpoisoned animals fell within the limits of experimental error, so 

 that there had been no increase in the fat of the body as the result of 

 the poisoning. In some of these cases the liver is actually enlarged, 

 but this deposition of fat in the cells is due to the immigration of the 

 fat from other parts of the body and not to conversion of the protein 

 ot the cells. This is shown by the facts that the composition of the 

 fat in the degenerated liver varies according to the composition of the 

 fat in the rest of the body, and that, if abnormal fats are given with 

 the food, such as erucic acid or iodine fats, these are found in the fat 

 extracted from the liver. In fatty degeneration two processes are 

 at work : one is the immigration of fats from other parts of the 

 body ; the second, and probably the more important one, is a change 

 in the relation of the fat to the protoplasm of the cell. 



It was long stated that the fat of milk was not increased by feeding 

 with fats, but only by feeding with proteins. More recent researches 

 have given contrary results. The dependence of the composition 

 of milk fat on the composition of the fat present in the body or 

 administered in the food is shown by the fact that cows fed on oil- 

 cake may produce a butter which is useless for commercial purposes 



