GLANDULAR CELLS OF THE FROG'S PANCREAS 395 



cells destitute of the network, there can be seen minute granules 

 or fine filaments scattered through the cytoplasm. In other 

 cells small clumps or rods are present above the nucleus (fig. 85). 

 Examination of still other cells shows that there are all grades 

 of transition between these clumps or rods and the typical net- 

 work (figs. 86, 87), which is formed by an anastomosis or a 

 fusion of the former. Whether these gradations are to be 

 regarded as developmental stages of the network or as a retro- 

 gression is a question which is difficult to answer. At any rate, 

 it is worthy of remark that the network is fixed in a definite 

 position above the nucleus which exactly corresponds to the 

 secretogenous area. We have also noticed that the prozymogen 

 granules occupy the meshes of the network; in other words, the 

 secretogenous area is traversed by the intracellular network. 

 It can further be seen in the preparations that the extent of the 

 secretogenous area, which varies according as the prozymogen 

 granules are increased or decreased, is in keeping with that of 

 the network. Under these circumstances, it seems probable 

 that the genesis of the zymogen granules and that of the net- 

 work must be in some way correlated with each other. How 

 this is accomplished, must for the present remain an open ques- 

 tion. It is conceivable, however, that the formation and growth 

 of prozymogen granules accompany an import and export of 

 substances, and that the substance given off deposits in the 

 secretogenous area and flows together, so as to form a network. 

 However this may be, it is quite certain that the secretion 

 process of the pancreatic cell is carried on in two ways: one 

 which is marked by the formation of granules and the other 

 in which the secreting material is deposited as unformed masses 

 from the beginning. In the former process the granules, from 

 the first formed prozymogen up to the mature zymogen granules, 

 preserve their individuality; they take up substances and per- 

 haps give them off, too. During growth, they gradually change 

 their properties and finally lose their individuality, fusing together 

 in order to form the secreting mass. The other process of secre- 

 tion, on the contrary, is characterized by the formation of secre- 

 tion material which is to be eliminated without undergoing 



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



