CONCERN1NG THE SECRETION OF FERMENTS BY THE LIVER CELLS 445 



especially in the small cells surrounding the portai tracts. The structureless 

 material is more abundant and arranged in masses. 



This séries of spécimens is chiefly remarkable for the very large size 

 attained by the spherules and their peculiar staining properties which 

 differ from those in other séries. They produce the same impression when 

 magnified 1200 diameters as vegetable tissue filled with starch grains does 

 under a magnification of 300. 



Why the spherules should be so large throughout this séries is difficult 

 to décide; whether or not it has anything to do with the food I am at 

 présent unable to détermine, but as their characters differ somewhat in 

 each séries and are fairly constant for any one séries it would seem that 

 the nature of the food has an influence upon them, the more so as in ail 

 the experiments the animais were kept to the same diet for some days 

 before the préparations were made, with a view of setting up digestive 

 processes suited to the particular diet administered, as we know that a 

 habit is readily set up in the digestive glands. 



This séries again shows two distinct periods of sécrétion, the one 

 slight, of short duration, corresponding to the lack of appetite and interest 

 manifested by the animais for a purely carbohydrate diet, and a second 

 more intense and prolonged, beginning about the fourth hour and prac- 

 tically recovered from by the end of the eighth hour. Starchy food evidently 

 does not call for a sécrétion of ferments from the liver cells so powerful or 

 so prolonged as either a mixed or a purely proteid diet. 



Fourth séries of experiments with a diet of pure fat. 



For this séries, the rats were given a full meal of beef suet after a fast 

 of 24 hours ; they had been fed for several days previously on beef suet to 

 accustom them to this kind of food. They appear tolerably fond of fat and 

 eat it willingly enough, though with nothing like the avidity with which 

 they seize upon raw méat. 



Appearances présentée! by the liver cells 1 hour after feeding, fig. 10. 



The cell outlines are just visible and pale in colour, many cells con- 

 tain large vacuoles, others show, in addition, many small ones, the cyto- 



59 



