GLANDULAR CELLS OF THE FROG'S PANCREAS 379 



direction. If such assumption is tenable, then the question 

 arises as to what part they play in the blood-vessel. Are they 

 to be regarded as mere decomposition products, or are they to 

 be taken up by other kinds of cells, exerting an influence in some 

 way upon the activity of the latter? I will take them in the 

 sense of Mathews as representing an internal secretion of the 

 pancreas cell. This is in agreement with a recent tendency to 

 ascribe the process of internal secretion not only to the islet cells, 

 but also to the parenchyma cells of the pancreas. 



D. Zymogen granules 



1. Technique. Zymogen granules can be well preserved in a 

 variety of sublimate mixtures and in many of the fixatives for 

 mitochondria, and can be stained with iron-haematoxylin, acid 

 fuchsin, etc. In preparations fixed in bichromate acetic acid, 

 alcohol, Carnoy's and Flemming's fluid, they are either imper- 

 fectly stained by iron-haematoxylin or remain unstained. From 

 this it appears that, in the fixatives containing a large amount of 

 alcohol or acetic acid, even if they contain osmic or chromic 

 acid, the affinity of zymogen granules for iron-haematoxylin is 

 much diminished, and that the sublimate mixtures, even if they 

 contain acetic acid, will preserve zymogen granules. That 

 acetic acid does not totally dissolve out or destroy zymogen gran- 

 ules, but perhaps acts upon them in such a way that a certain 

 constituent of the granules which has strong affinity for iron-hae- 

 matoxylin is removed, is evidenced from the fact that, although 

 the granules fixed in bichromate acetic acid remain unstained in 

 iron-haematoxylin, they can yet be demonstrated by staining 

 with eosin. In the preparations fixed in alcohol or Carnoy's, 

 on the contrary, they can no longer be stained even by eosin. 



2. Shape, size and position. As is well known, the secretion 

 granules of the pancreas are of spherical form and are accumu- 

 lated in the upper half of the cell. Their increase or decrease 

 has, in most cases, a marked influence upon the shape and size 

 of the glandular cell. Generally speaking, the cells containing 

 a few zymogen granules are smaller than those which are full of 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 26, NO. 3 



