936 METABOLISM. 



acids of the liver of the rabbit at a period after food when the glycogen 

 is diminishing, and he concludes that they may have been formed from 

 the glycogen. 1 Langley 2 has shown that in frogs there is a gradual 

 accumulation of fat in the liver, chiefly in the outer zones of the cells, 

 during the winter months, a time during which the glycogen is also 

 gradually increasing ; and, further, that both the liver fat and glycogen 

 tend to diminish on warming the animals in winter. The glycogen 

 becomes rapidly used up in the spring, and this is also the case with 

 the fat. Paton found (in pigeons) that the liver fat did not appreciably 

 diminish as the result of a four days' fast. Taken by itself, the presence 

 of fat in the hepatic cells merely indicates that these cells may act as a 

 temporary storehouse for fat. Whetlier such fat has been formed by 

 them from carbohydrate or proteid, or whether it is directly derived 

 from the fat of the food, and is in process of transformation in the 

 liver cells into a fat more intimately allied to the fat of the body, are 

 points which have not yet been determined, but the latter supposition 

 appears the more probable ; for excess of fat in the food is certainly 

 largely stored in the liver cells. 3 And it has been noticed by Lebedeff, 4 

 and this observation is confirmed by Paton, 5 that the fats of the liver 

 contain less oleic acid, and have a higher melting point, than those of 

 the body generally. Moreover, as Hofmann showed, 6 there is a higher 

 proportion of free fatty acids in the liver, pointing, according to Nasse, 

 to an active metabolism of fats in that organ. 7 Lebedeff 8 found in 

 geese which had been fed for six weeks upon peas, which are rich in 

 proteid but contain very little fat, that the liver, although containing 

 much lecithin, had no fat ; and that the fat of the omen turn was also 

 only present in small amount. A large amount of proteid in the diet 

 of rabbits and kittens was found by Paton not to lead to any accumula- 

 tion of fat in the liver. 9 



1 According to Paton, nearly one-half of the fatty acids of the liver are in combination 

 with lecithin. See also Heffter, Arch. f. expcr. Path. u. Pharmakol., Leipzig, 1891, Bd. 

 xxviii. S. 97 ; and Stolnikow, Arch. f. PhysioL, Leipzig, 1887, Suppl. Heft. S. 1. 



2 Loc. cit. 



3 Paton, loc. cit., p. 202. 



4 Ztschr.f. physiol. Chem., Strassburg, 1882, Bd. vi. S. 139. 



5 Loc. cit., p. 179. 



6 Beitr. 2. PhysioL C. Ludwig z. s. 70, Geburtst., Leipzig, S. 134. 



7 Biol. CentralbL, Erlangen, 1886-7, Bd. vi. S. 235. 



8 Loc. cit. 9 Loc. cit., p. 211. 



