PHYSIOLOGY OF PEPSIN-FORMING GLANDS. 
705 
I think that it is due to the granules being used up in the one part of the cell faster 
than in the other, I am unable to offer any satisfactory proof that it is so. 
On the cause of the outer non-granular zone which is formed in the oesophageal 
glands of the Frog, I would, however, offer a few remarks. I take the oesophageal 
glands only as a convenient example, my remarks will equally apply to the gastric 
glands of the Newt and other glands in which an outer non-granular zone is formed 
during secretion. 
In the oesophageal glands we have seen that the cell-granules diminish in size 
during activity ; if, then, in any part of the cells the granules are being used up more 
quickly than in another the granules will be smaller in that part than elsewhere. 
The diminution in the size of the granules tabes place, however, equally in all parts 
of the cell, consequently we may conclude that the non-granular zone is not caused by 
any variation in the rate of using up granules in the inner and outer portions of 
the cells. 
We have then to fall back on local variations in the rate of growth of the cell- 
protoplasm to explain the appearances. Will the assumption of a rapid growth of 
protoplasm at the outer part of the cell suffice to explain the formation of the outer 
non-granular zone ? I think not, for several reasons. It seems to me necessary to 
assume that there is another factor in the result, viz.: a translation of the granules 
towards the lumen by the cell. 
In the oesophageal and other similar glands the first sign of the subsequent zones is 
a diminution in the number of granules in the outer portion of the cell. If this is 
due to a growth of protoplasm the protoplasm must grow in the outer one-third to 
one-half of the cell. How, then, can the further increase of protoplasm give rise to a 
non-granular outer zone and a densely granular inner one at all sharply marked off the 
one from the other ? In passing from the granular to the non-granular zone there 
should be a very obvious region where the granules become fewer and fewer. 
In certain circumstances the oesophageal glands of the Frog contain compara¬ 
tively few granules, these being scattered throughout the cells (see Plate 77, fig. 7). 
During activity such glands show distinct zones. How could zones in such a case be 
produced by a growth of protoplasm unaccompanied by a direct movement of the 
granules in the cells ? 
Again, in glands when the granules have completely disappeared, can we suppose 
that the protoplasm has completely regrown from the periphery ? 
An observation of Heidenhain’s* upon the pancreas of the Rabbit is, I think, in 
favour of the view that the granules are moved towards the lumen. He found that 
when a piece of fresh pancreas was warmed to about 50° C. the granules moved out¬ 
wards into the clear zone, and returned to their original position when the tempera¬ 
ture fell. He, too, pointed outt that cells which were granular throughout, on being 
removed from the body gradually developed an outer non-granular zone as they died. 
* Pflugek’s Archiy., Bel. x., s. 563, 1875. 
f Op. nit., s. 559. 
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MDCCCLXXXT. 
