CHAP, i.] TISSUES AND MECHANISMS OF DIGESTION. 347 



these cells may, though with difficulty, be examined in the living 

 state. They are then found to be studded with granules when 

 the stomach is at rest. During digestion these granules become 

 much less numerous and are chiefly gathered near the lumen, 

 leaving in each cell a clear outer zone. And in many mammals 

 the same abundance of granules in the loaded cell, the same 

 paucity of granules for the most part restricted to an inner zone 

 in the discharged cell, may be demonstrated by the use of osmic 

 acid, Fig. 82. 



When the stomach is hardened by alcohol these changes, like 

 the similar changes in an albuminous cell, are obscured by the 

 shrinking of the ' granules ' or by their swelling up and becoming 

 diffused through the rest of the cell-substance ; so that though, in 

 sections so prepared, very striking differences are seen between 

 loaded and discharged cells, these are unlike those seen in living 

 glands. In specimens taken from an animal which has not been 

 fed for some time, the central cells of the gastric glands are pale, 

 finely granular, and do not stain readily with carmine and other 

 dyes. During the early stages of gastric digestion, the same cells 

 are found somewhat swollen, but turbid and more coarsely granu- 

 lar ; they stain much more readily. At a later stage they become 

 smaller and shrunken, but are even more turbid and granular than 

 before, and stain still more deeply. This is true, not only of the 

 central cells in the cardiac glands, but also of the cells of which 

 the pyloric glands are built up. In the loaded cell very little 

 staining takes place, because the amount of living staining cell- 

 substance is small relatively to the amount of material with which 

 it is loaded and which does not stain readily. In the cell which 

 after great activity has discharged itself, the cell is smaller, but 

 what remains is largely living cell-substance, some of it new, and 

 all staining readily. It would appear also that during the activity 

 of the cell some substances, capable of being precipitated by alco- 

 hol, make their appearance, and the presencs of this material adds 

 to the turbid and granular aspect of the cell ; possibly also this 

 material contributes to the staining. A similar material seems to 

 make its appearance in the cells of albuminous glands. 



In the ovoid or border cells no very characteristic changes 

 make their appearance. During digestion they become larger, 

 more swollen as it were, and in consequence bulge out the 

 basement membrane, but no characteristic disappearance of gran- 

 ules can be observed. In the living state, the cell-substance of 

 these ovoid cells appears finely granular, but in hardened and 

 prepared sections has a coarsely granular, "reticulate" look which 

 is perhaps less marked in the swollen active cells than in the 

 resting cells. 



199. All these various secreting cells then, pancreatic cell, 

 mucous cell, albuminous cell, and central gastric cell, exhibit the 

 same series of events, modified to a certain extent in the several 



