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MR. J. N. LANGLEY ON THE HISTOLOGY AND 
He points out'" two differences between the changes which occur in the pancreatic 
and gastric glands. First, that the regeneration of the used-up material takes place 
in the pancreas whilst the gland is still secreting, but does not in the gastric glands. 
Secondly, that in the pancreas the granules are formed out of the homogeneous outer 
zone, and in the gastric glands out of the finely granular cell protoplasm. As to the 
first point of difference, we have seen that in the Frog, Newt, and Toad the used-up 
material is regenerated more or less completely whilst secretion is still going on. The 
second point of difference chiefly rests on the assumption that the protoplasm of the 
fresh cell is finely granular, since in alcohol specimens an increase of protoplasm in the 
cell is marked by an increased cloudiness. 
The differences which exist with regard to the formation of granules in those cells 
which acquire an outer non-granular zone in activity and those which do not we shall 
discuss later. We have first to consider what facts we have to support the view given 
r above as to the changes which take place in the pepsin-forming glands during 
secretion. 
We have to show that (a) the using up of granules, (6) the formation of granules, 
and (c) the growth of protoplasm all go on from the beginning to the end of secretion. 
(a.) Since it has been shown that the granules give rise to pepsin, and since we 
know of no other origin for pepsin, we may conclude that as long as pepsin is formed, 
i. e ., as long as the secretion goes on, granules are used up. 
(6.) We have seen that in all cases in the latter half to two-thirds of the digestive 
period the granules increase. There can be no doubt that during this time a secretion 
is going on ; this is indeed shown by feeding a Frog or Newt with sponge. It is then 
seen that the simple mechanical stimulation caused by the presence of a foreign body 
in the stomach is sufficient to cause a secretion lasting for two or more days. 
Heidenhain, too, has shown that in the Mammal secretion of gastric juice goes on as 
long as food remains in the stomach. But since a secretion means a using up of 
granules, there is during a large part of the digestive period a using up and formation 
of granules going on at the same time. 
We have also seen that in certain circumstances an increase of granules occurs in 
the first hours of digestion. During this time there is also a using up of granules, 
that is, the two processes go on together, sometimes at any rate in the first hours of 
digestion. 
Now, when we consider that the using up of granules is continually going on, and 
that the formation of granules certainly takes place in the latter digestive period and 
sometimes in the first digestive period, and further consider that the formation of 
granules can only become obvious in the glands when it takes place at a faster rate 
than the using up, the conclusion seems irresistible that there is a formation of granules 
during the whole digestive period, but that during the first five to ten hours it is not 
sufficiently rapid to cover the loss from the using up of granules. In certain circum- 
* Hermann’s ‘ Handbucli d. Physiol.,’ Bd. v., s. 202, 1880. 
