298 EVIDENCE AS TO THE FORMATION OF FAT 



been kept in hot stalls, over-richly fed, and given deficient exercise. 

 This condition was at once remedied by giving proper exercise to 

 the mares. In this and every other pathological case Rosenfeld 

 argues that the fat is brought from the depots, that the tissues 

 undergo fat infiltration, not fatty degeneration. In the conditions 

 of intoxication and mal-nutrition the cells increase their energy 

 at first by oxidation of glycogen hence the total disappearance 

 of glycogen in phosphorus, chloroform, phloridzin, arsenic poison- 

 ing finally they fall back upon fat and take up increasing 

 quantities of this from the depots through the blood. The 

 probability of this view is established by the fact that feeding 

 glycogen-producing foods lowers the onput of fat in the liver. 

 Thus in phloridzin or alcohol poisoning the fat infiltration 

 can be prevented by feeding glycogen builders, and dogs which 

 on a pure fat diet put on 25 per cent, of dry liver substance as 

 fat have this percentage lowered to half or less by feeding glycogen 

 builders at the same time. The restoration of a fatty liver after 

 poisoning by phosphorus, &c., is signalised by the return of 

 glycogen. In the aseptic autolysis of organs the microscope 

 reveals apparent signs of fatty degeneration of the cells ; but here 

 again chemical analysis shows that the percentage of fat is not 

 increased. 



In the case of salmon it has been suggested that the fat of the 

 generative organs is formed at the expense of the muscle proteids. 

 The salmon, on entering fresh-water rivers for the purpose of breed- 

 ing, cease to feed, and may fast from five to fifteen months. They 

 enter the river with maximally developed muscles and minimally 

 developed generative organs. During the ascent of the river the 

 ovaries increase to J of the body weight. In the muscles of the 

 back, which atrophy as the organs of generation grow, Miescher 

 found enough proteid and fat available to build respectively the 

 proteid and fat of the ovary. There was no evidence of transforma- 

 tion of proteid into fat. The muscle fibres do not degenerate but 

 dwindle in size, and again become restored when the fish return to 

 the sea. 



There is no evidence that the developing chick can build fat out 

 of the proteids of the egg. In the new-laid egg there is about 10 

 per cent, fat, after seven days' incubation 9 per cent., and after 

 twenty-one days 6 per cent. Until the chick can feed itself on fat 

 and carbohydrate, the fat contents of its body decreases, consumed 

 as it is to supply the energy of growth. 



