PHYSIOLOGY OF PEPSIN-FORMING GLANDS. 
687 
distinct network. During digestion the cells of the pyloric glands frequently bulge 
in a very marked manner at their outer border; but from the inconstancy with which 
the bulging occurs I am not inclined to consider it a genuine result of secretion. 
Changes which occur in the Oxyntic Glands. 
The e ffect of fasting is more marked in Triton tceniat us than in any other animal 
which I have examined. In the anterior oxyntic glands a more or less distinct outer 
non-granular zone is formed : in the posterior oxyntic glands the clear zone is less 
distinct, but other changes are obvious ; the cells are smaller, the lumen usually 
distinct, and the cell-substance stains more deeply with osmic acid. The mucous cells 
in the necks of the glands increase in mucigen—at any rate up to the time when 
the outer zone begins to be distinct in the anterior oxyntic glands. 
Changes during digestion .—The diminution of granules which takes place in the 
living glands of a Newt after feeding it, has been described by Sewall and myself. '' 
This diminution can also be seen in osmic acid specimens of the gastric mucous mem¬ 
brane, in such specimens some other changes can be seen which are less obvious in the 
fresh tissue. The anterior differ somewhat from the posterior oxyntic glands in the 
changes they undergo ; in the former the outer clear zone is usually more distinct 
during digestion than in the latter, and in the latter the increase of the lumina and 
decrease in the size of the cells and granules is usually more distinct than in the 
former. These changes go on in all the glands, but to an unequal degree in the two 
glandular regions. 
When the living glands are examined in the first or second hour of digestion the 
granules frequently appear at first sight larger than normal;! this is, I think, only 
caused by many of the granules having disappeared, so that instead of a confused 
granular mass, the separate granules can be distinctly seen. Osmic acid specimens 
show that at any rate about the second hour the granules are smaller. It is note¬ 
worthy that as the granules become smaller during cell activity they vary much more in 
size than do the granules of the resting gland (see Plate 78, figs. 3 and 4, 2 and 6). 
The extent and time of the changes vary widely under varying circumstances. In a 
normal hungry Newt fed with a small worm the following is the ordinary course of 
events as followed in successive osmic acid preparations. 
A thinning of granules at the outer border of the cells is visible in half-an-hour to 
one hour; the nucleus and cell-substance begin to stain slightly. Usually at the end 
of an hour a decrease in the size of the cells and the cell-granules is to be seen. 
These changes then proceed rapidly, the time of maximum change being three to 
four and a-half hours from the beginning of digestion. The cells and cell-granules are 
then very distinctly smaller (see Plate 78, figs. 3 and 4), and a more or less distinct 
* Op. cit. 
f They were so described by Sewall and myself from the examination of fresh specimens. 
