PHYSIOLOGY OF PEPSIN FORMING GLANDS. 
675 
very heavy meal, or in certain abnormal circumstances, that the lumen becomes large 
and conspicuous. 
The disappearance of granules from the inner portion of the cells is little or not at 
all marked in the fresh specimen. No distinct zones, such as occur in the oesophageal 
glands, are formed. 
Examination of specimens treated with osmic acid.— In order to make out more in 
detail the changes which take place, the stomach is pinned out in osmic acid for 
twenty-four hours and then put into alcohol. The best preparations are obtained 
when the tissue is left in alcohol for several days before sections are made, so that the 
cells are stained of a black instead of a yellow-brown tint. 
In the resting state the glands show no lumina, the cells are crowded with fine 
granules, and through the granules the nuclei appear as clearer spots, the cell outlines 
being very faintly marked (Plate 77, fig. 9); the cell-substance is almost unstained. 
It will be convenient to consider first the changes which take place in a healthy 
summer Frog fed with a worm small enough for the stomach to have emptied itself 
completely in twenty-four hours. 
In one to two hours after feeding, the lumina begin to be obvious, and the granules 
to disappear from the inner borders of the cells. This causes the glands to assume a 
very characteristic appearance. When examined with obj. C or D (Zeiss) a clearer line 
is seen to run down the middle of each gland; it is usually of a zig-zag or corkscrew 
form; the form being naturally dependent upon the arrangement of the cells in the 
gland-tube (Plate 77, fig. 10). 
Up to about the fifth hour these changes become more and more pronounced, and at 
the same time the cells and the remaining granules they contain become distinctly 
smaller, and the cell-substance stains more deeply. 
It is noteworthy that the granules do not disappear simply from that part of the 
cell which immediately borders the lumen, but to some extent also at the sides of the 
cells where they are in contact with one another (see Plate 77, fig. 11). The dis¬ 
appearance of granules at the sides of the cells does not extend to the basement 
membrane. 
At the period of maximum change the nucleus is much larger compared with the 
cell-substance than it is during rest; it is still surrounded by finely granular proto¬ 
plasm and is sometimes placed near the outer border of the cell, in this differing from 
the nuclei of gland-cells hitherto observed. Very frequently the granules appear to 
be most numerous in the cell-substance immediately on the inner side of the nuclei. 
The return to the normal appearances begins about the fifth hour; so that during 
the greater part of the digestive period the formative processes go on whilst the 
excretory are still active. In twenty-four hours the glands have nearly or altogether 
returned to the hungry condition. 
The above I regard as the normal round of changes in the oxyntic glands of the 
Frog during digestion. 
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