694 
ME, J. N. LANGLEY ON THE HISTOLOGY AND 
The analysis showed that the diminution in the amount of ferment in passing from 
the beginning to the end of the stomach was much more rapid than in the previous 
case. In parts three and four a comparatively feeble pepsin action was found—in 
three, rather more than in four ; the difference in rapidity of action between the 
second part and the fourth was considerably greater than between the fourth and the 
pyloric region. In the normal hungry Snake the amount of pepsin contained by a 
definite weight of dried mucous membrane also diminishes from the anterior to the 
posterior portion, but to a much less extent than in the digesting animal. The 
amount of pepsin contained by the pyloric region is very small, although, as hi the 
Frog, Newt, and Toad, quite appreciable. In the Snake I compared the amount ot 
pepsin contained by equal weights of oesophagus and pyloric gland region; from the 
former I obtained no pepsin reaction. 
It will be noticed that in all cases the amount of pepsin contained by a definite 
weight of mucous membrane varied directly with the granularity of the gland-cells. 
In the above experiments the dried mucous membrane was extracted with dilute 
hydrochloric acid; quite similar results are, however, obtained if the dried mucous 
membrane be extracted with glycerine, and the glycerine extract tested for pepsin. 
I have made some experiments to determine whether the gastric glands of the 
Snake contain pepsinogen. Since I propose considering in detail in a later paper the 
question of the formation of pepsinogen in gastric glands, I will here only mention 
that the stomach of the Snake contains a very considerable amount of a substance 
insoluble in glycerine, but which when treated with dilute hydrochloric acid gives 
rise to pepsin, and that this substance is in greatest quantity in the anterior region of 
the stomach, and diminishes in amount in passing towards the posterior region. 
General Conclusions on the Secretory Processes in Pepsin-forming Glands. 
From the preceding details some general conclusions can, I think, be drawn. 
Pepsin is formed from the granules seen in the gland-cells in the living state. 
An account has been given above of the pepsin-content of the stomach and of 
various parts of it in Rana temporaria , Bufo vulgaris, Triton tceniatus, Triton cristatus, 
and Coluber natrix. By the method used, viz.: extraction of the dried tissue with 
hydrochloric acid 0'2 per cent., the total amount of free and combined pepsin* present 
in the tissue was obtained. 
* Grutzner (Neue Hnters. ii. d. Bildung u.Ausscheidung d. Pepsins § 26, 1875) lias pointed out that 
this method only gives accurate results under certain conditions, viz.: (1) when a relatively large 
quantity of hydrochloric acid is used for extraction; (2) when the extraction proceeds for at least ten 
hours; (3) when the amount of tissue is not too great compared with the amount of pepsin. The first 
two conditions were complied with in all my experiments. With regard to the last, it may result that 
the amount of pepsin contained by the pyloric glands is greater than that which I have found. 
