22 On the Histology, fyc, of Pepsin-forming Glands. [Mar. 24, 



diminution of grannies in the gland-cells of Triton cristatus is enor- 

 mously less than the observable diminution of granules in the gland- 

 cells of Triton tceniatus. 



This can, I think, only result from the formation of granules pro- 

 ceeding more hand-in-hand with the using up in the former than in 

 the latter. 



This and other similar facts lead us to conclude that the differences 

 in the amount of histological change which takes place in the pepsin- 

 forming glands of different animals, is the consequence of the three 

 changes above-mentioned proceeding in each animal at different 

 relative rates. 



It is well known that in various glands, typically the pancreas, the 

 granules are found during secretion aggregated around the lumina, 

 the outer portions of the cells being non-granular and homogeneous. 

 The cause of this appearance is, no doubt, in part due to a more rapid 

 growth of protoplasm in the outer than the inner portions of the 

 cells ; in part, also, I think it is due to the granules being moved by 

 the protoplasm towards the lumen. It is necessary, I think, to 

 assume such a transference of granules, since neither the unequal 

 growth of protoplasm, nor, what might also be imagined, an unequal 

 using up of granules in the two regions of the cells, is sufficient to 

 account for the changes which take place. Since the granules before 

 they disappear become smaller, they will be smaller in that part of 

 the cell in which they are being used up most actively. But, as a 

 matter of fact, the granules are equally affected throughout the cell, 

 so that the outer clear zone cannot a,rise from a more rapid using up 

 of granules in that part of the cell. As to the more rapid growth of 

 protoplasm, it fails to explain how the granules, which in the first 

 stage of digestion become few and scattered in the outer half of the 

 cell, can in the latter stages of digestion be arranged in a dense mass 

 around the lumen ; it leads, moreover, to the very improbable hypo- 

 thesis that when the granules have entirely disappeared from the cells, 

 the cell protoplasm has completely regrown from the periphery. 



The pepsin-forming glands which we are considering in this paper, 

 offer some other interesting forms of cell activity. In some no dis- 

 tinction of zones occurs, the granules become smaller and less 

 frequent in all parts of the cells, without any alteration in their 

 relative distribution ; in others there is formed a small non-granular zone 

 in the inner part of the cells. This inner non-granular zone, though 

 obvious enough in certain states of the glands, does not reach the 

 proportions which the outer non-granular zone attains in the pancreas 

 and other similarly constructed glands. 



Further, we find, in these glands, all stages of transition between 

 the three types of cell-change in activity which have just been men- 

 ■tioned. Thus, the oesophageal glands of the frog form a large outer 



