PHYSIOLOGY OF PEPSIN-FORMING GLANDS. 
073 
During prolonged fasting a diminution of granules occurs. The amount of diminu¬ 
tion varies in different Frogs, and varies with the time of year: it is less in winter 
than in summer. In most cases the granules only become fewer at the outer borders 
of the cells ; in others a clear zone is formed. Thinning of granules, however, rather 
than the formation of a clear zone, seems to me to he the normal effect; for in all the 
■perfectly healthy December Frogs I have examined, the granules, though fewer at the 
outer part of the cells, still extended to the periphery. Some diminution in the size 
of the cells also takes place. 
I conclude, then, that in a healthy Frog during the winter months fasting does not 
necessarily produce a distinct noil-granular zone in the oesophageal glands. In other 
months when the tissue change is more rapid, fasting may produce a non-granular 
zone, but I think the most usual and effective cause of such a zone is some alteration 
in the general condition of the body, independent of fasting, by which the normal 
equilibrium in the gland-cells is disturbed. 
My experiments have only been made on Rana temporaria; in other species of Frogs, 
fasting may have a greater effect, just as the effect is greater in Triton tcenialus than 
in Triton cristatus. 
It remains to consider how far an increase of granules takes place immediately after 
feeding. Nussbaum considered that the granules always increase in the first hours of 
digestion, but it is to be remembered that his observations were made on Frogs in 
which the oesophageal glands had a non-granular zone before feeding. Giiutzner onlv 
found an increase of granules in the first hours of digestion when a clear zone had 
been previously developed in the oesophageal glands by long fasting. In both cases, 
then, the increase is only described as taking place in glands having a non-granular 
zone to start with. 
The method of experimenting contains an obvious source of error. We do not know 
with certainty what is the state of the glands before feeding, and therefore cannot say 
positively whether an increase or decrease of granules takes place. My own observa¬ 
tions lead me to conclude that in a normal hungry Frog no increase of granules takes 
place in the first hours of digestion, and that in abnormal Frogs, i.e., in those having 
already zones in the oesophageal glands, an increase may or may not take place. I 
have seen only one instance of apparent distinct increase, and I am by no means 
certain that it was not simply apparent. 
I am not prepared to deny that a slight increase may not take place in all cases, for 
I think our present methods do not allow us to detect slight differences in the amount 
of granules contained by gland-cells. Further, I am strongly of opinion that a forma¬ 
tion of granules goes on during the whole digestive period, and I can readily conceive 
that under certain circumstances the formative might overbalance the excretorv 
processes in the first hours, as they certainly do in the last hours of digestion. 
4 s 
MDCCCLXXXI. 
