A manual of physiology : for students of medicine / by Gerald F. Yeo.

  • Yeo, Gerald F., 1845-1909.
Date:
1884
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Licence: Public Domain Mark

Credit: A manual of physiology : for students of medicine / by Gerald F. Yeo. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

    171/766 (page 159)
    It will be seen immediately that one of the most important functions of the pancreatic juice is the formation of peptone from proteid, which operation is carried out by a special ferment called trypsin. It has been found that this ferment cau only be obtained from the active pancreas, and that the wider the inner granular zone of the cells is, the richer in ferment is the glycerin extract made from the gland. But it has been found that if a glycerin extract be rapidly made from an actively secreting absolutely fresh gland, i.e., removed from the dead animal while still warm, the extract is found to be quite inert towards proteids, while an extract made from a portion of the same pancreas which has been kept some hours after death is very active; and a portion of the fresh pancreas pounded in a mortar with a little weak acid so as to develop the trypsin in it, acts in an alkaline solution and forms peptone energetically. We must therefore conclude that the special proteolytic fer- ment of the pancreas does not exist prior to the period at which the secretion is poured out from the gland cells. Although a definite relation seems to exist between the amount of granules in the active cells and the degree of efficacy of the secretion, the ferment does not appear in full force for some time after that the height of the gland activity has been established, and it is likely that the presence of an acid helps in the birth of the ferment. It has therefore been assumed that the granules of the gland cells give rise, not to the proteolytic ferment, but to a ferment- producing substance which is called Zymogen. So that if we trace the history of the pancreatic proteolytic fer- ment, we shall find that, so far as this trypsin is concerned, there can be no question as to whether it pre-exists in the blood and is removed thence by the gland or not, because by studying the process we find that the final elaboration of the secretion takes place after it has got into the ducts or the intestinal cavity. Thus the blood gives to the protoplasm of the gland-cells nutriment. The proto- plasm of the cells, by its intrinsic chemical processes, manufac- tures peculiar granules. These granules give rise, among other