CONCERNING THE SECRETION OF FERMENTS BY THE LIVER CELLS 433 



Mann' s methyl blue eosine (long method), Mann's toluidin blue eosinc, 

 Mac Allum's method for unmasking albuminoid iron and M. Heidenhain's 

 iron alum haematoxylin method for photographie purposes. The sections 

 were cleared in inspissated turpentine and mounted in turpentine balsam. 

 The examination was carried out with Leitz 1/12 oil immersion objective 

 and No. 1 2 compensating eyepiece. 



First séries of experiments in with the animais were îed on a mixed diet 

 containing proteids, fats and carbohydrates, i. e. bread and milk. 



Thirteen adult maie white rats of approximately the same weight and 

 âge were kept each in a separate cage in the same room and fed on a mixed 

 diet for three weeks, to create a digestive habit. At the end of that time 

 they were made to fast for 24 hours; twelve were now fed with a full meal, 

 as previously calculated, of the same mixed diet, and the thirteenth killed 

 fasting as a control. Of the fed rats one was killed at the end of every hour 

 until the whole had been sacrificed. 



Appearances presented by the liver cells of the fasting rat, fig. 1. 



In the rat, Glisson's capsule is reduced to a minimum. Nevertheless, 

 with a little care, it is possible to détermine accurately the boundaries of 

 the lobules. For this purpose methyl blue is very helpful, as it stains ail 

 connective tissues intensely blue. During fasting the envelope of the liver 

 cell is distinctly visible, and the cytoplasm fills it completely in an uniform 

 manner, i. e. there is no vacuolation présent in the cells except in a few 

 cases where a somewhat clear space immediately surrounding the nucleus 

 may be observed. Contained in the cytoplasm is an apparently structureless 

 material arranged in clumps, more abundant in some cells than in others, 

 though présent to some extent in ail. It is best seen in spécimens stained 

 with toluidin blue eosine, in which it assumes a deep red colour, whilst the 

 cytoplasm, amongst which it lies, is reddish grey, and with Heidenhain's 

 haematoxylin it stains deep black. What the nature of this material may be 

 I can at présent only surmise. It is not glycogen because (a) it is abundant 

 after a long fast, and (b) because it gives none of the reactions charac- 

 teristic of that substance; neither is it due to the action of any particular 

 fixative, for it is présent in spécimens prepared from the liver oi ail the 



