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. Whether 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 omentum 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. exper. Path. u. Pharmakol., Leipzig, 1891, Bd. 
xxviii. S. 97 ; and Stohiikow, Arch. f. Physiol., Leipzig, 1887, Suppl. Heft. S. 1. 
2 Loc. cit. 
3 Paton, loc. cit. , p. 202. 
4 Ztschr.f. physiol. Chcm., Strassburg, 1882, Bd. vi. S. 139. 
5 Loc. cit., p. 179. 
6 Bcitr. z. Physiol. G. Ludwig z. s. 70, Gchurtst., Leipzig, S. 134. 
7 Biol. CcntralbL, Erlangen, 1886-7, Bd. vi. S. 235. 
8 Loc. cit. H Loc. cit., p. 211. 
