PHYSIOLOGY OF PEPSIN-FORMING GLANDS. 
697 
When the secretion produced by a gland contains undissolved particles, these particles may be stored up 
by the gland, thus fat globules are apparently stored up by the cells of the Harderian and Mammary glands. 
I do not overlook the fact that a glycerine extract of the fresh Mammalian gastric mucous membrane 
contains a good deal of pepsin, but I believe this to be due simply to the zymogen being more easily split 
up in these glands than in others. It will be remembered that the granules of the “chief” cells which 
probably consist in part or wholly of zymogen are not preserved by osmic acid; i.e., these zymogen 
granules split up with osmic acid, whilst the other zymogen granules we know of do not. Further, as 
mentioned above, Ebstein and Grutzneb have shown that the gastric glands of Mammals do contain 
some zymogen. 
The general course of reasoning given above, led me to make some direct experi¬ 
ments on the subject. The result completely confirmed the justice of the deductions 
drawn from microscopical examination. Since I propose to discuss in a later paper 
the whole question of the formation of pre-products by gland-cells, I will here only 
briefly mention the main facts which show that zymogen and not ferment is stored up 
by the glands we are considering. 
If the oesophagus or stomach of a Frog be placed in glycerine as rapidly as possible 
after removal from the body, the glycerine extract has only a weak peptic power. 
If the oesophagus or stomach of a Frog be kept moist for twenty-four hours before 
it is placed in glycerine, the glycerine extract lias a very much greater peptic power. 
If the oesophagus and stomach which has been extracted with, say, 5 cub. centims. of 
glycerine for a week be washed free of glycerine and treated with 5 cub. centims. of 
dilute hydrochloric acid, then an enormously greater amount of pepsin is found in the 
acid than is found in the glycerine extract. 
The glycerine extracts increase somewhat, although only slightly, in peptic power 
when treated with dilute acid for twenty-four hours. 
Since in testing a glycerine extract for pepsin, hydrochloric acid is added, it is possible that even the 
small amount of pepsin found in it may arise from the splitting up by the acid of combined pepsin. 
These facts, I think, show that both the oesophageal and gastric glands form zymogen 
which under certain conditions, and particularly when acted on by dilute acids, give 
rise to pepsin. The zymogen is only slightly soluble in glycerine. 
Similar observations made on the gastric glands of Triton tceniatus give similar 
results. In the Snake, lack of animals has prevented me from comparing the pepsin- 
content of glycerine extract of the fresh with glycerine extract of the exposed stomach, 
but the experiment mentioned above (p. 694) shows that the gastric glands of the 
Snake also contain zymogen. 
Since the pepsin of the oesophageal and gastric glands which we have considered 
arise from granules which are visible in life, the fact that the pyloric glands show no 
granules in life and yet apparently form pepsin may seem to require explanation. 
We know that there are many cells which consist of protoplasm* and inter-proto- 
* I use the word protoplasm for all living substance. I take the network which Klein and others 
have shown exists in so many gland-cells to be protoplasm, and the interhbrillar substance to be chieflv 
at any rate stored up material. 
MDCCCLXXXI. 
4 x 
