1885.] 



Fat in the Liver- Cells of the Frog. 



237 



Further we have seen that in winter-frogs kept in the warm, and in 

 fed winter-frogs, there is commonly an increase in the number of 

 fat-globules in the inner zone although the total amount of fat is 

 much diminished. Hence probably there is in certain circumstances 

 a transference of fat-globules from the outer to the inner part of the 

 cells. The amount of fat present in the liver of course depends upon 

 the relative rates of formation and metabolism of fat, and as this varies 

 in different circumstances, so probably the rate of transference of fat 

 from the outer to the inner cell- region varies in different circum- 

 stances. To this the differences spoken of above are probably due. 

 In summer frogs for example, whilst in the later stages of digestion 

 fat is formed more rapidly in the outer cell-region, an accumulation 

 of fat in this region may not take place; partly on account of the more 

 rapid metabolism of the' fat formed, and partly on account of its more 

 rapid transference to the inner cell-region. 



Some of the fat-globules in the inner zone are no doubt passed out of 

 the cell with the bile secreted, for some small fat-globules are always 

 present in the bile. 



One other conclusion we may draw with regard to the fat-globules : 

 since they diminish in size under the influence of warmth, and in the 

 first stage of digestion, it is probable that each separate fat-globule is 

 slowly metabolised in the same way that mesostate granules in 

 secretory glands are metabolised. The granules of the salivary 

 glands, of the gastric glands, of the pancreas, are not dissolved as a 

 whole during secretion, they are dissolved steadily and gradually. 



The Effect of Peptone and of Dextrin. — From June to August, 

 peptone or dextrin, when injected into the dorsal lymph-sac of a frog, 

 produces changes like those produced by feeding ; i.e., there is at first 

 a decrease in the amount of fat in the liver, then an increase chiefly 

 in the outer part of the cells, and this is succeeded by a decrease to 

 the normal state, during which the fat-globules become shifted from 

 the outer to the inner cell-region. The increase of fat is usually 

 greater with dextrin than with peptone. As a rule the increase in the 

 amount of fat takes place three to four hours after peptone has been 

 injected ; in twenty to thirty hours after the injection, the fat-globules 

 are present, as at starting, in the inner cell-region only. The times 

 at which the various changes take place vary, however, in different 

 frogs. If frogs are kept in the warm and peptone is injected, the 

 effect on the fat in the liver is much less than when the frogs are at 

 the ordinary temperatures. In September the effect of peptone 

 appears to be less than from June to August. In the winter months 

 I have not made a sufficient number of experiments to be certain what 

 changes peptone and dextrin then produce. 



Sewall has pointed out that peptone injected into the dorsal sac of 

 a frog, causes, in one to two hours, the stomach to be distended with 



