This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1894 edition. Excerpt: ...somewhat, I trust, by the results I have been able to contribute to it during the last twelve years. General Nature of the Proteolytic Enzymes.--These peculiar bodies owe their origin to the constructive power of the gland-cells from which the respective secretions are derived. During fasting, the epithelial cells of the gastric glands and of the pancreas manufacture from the cell-protoplasm a specific zymogen or ferment antecedent, which is stored up in the cell in the form of granules. These granules of either pepsinogen or trypsinogen, as the case may be, are during secretion apparently drawn upon for the production of the ferment, and it is an easy matter to verify Langley's 6 observation that the amount of pepsin, for example, obtainable from a definite weight of the glandbearing mucous membrane is proportionate to the amount of granules contained in the gland-cells. During ordinary secretion, however, these granules of zymogen do not entirely disappear from the cell. When secretion commences and the granules are drawn upon for the production of ferment, fresh granules are formed, and inasmuch as these latter are produced through the katabolism of the cell protoplasm it follows that anabolic processes must be simultaneously going on in the cell, by which new cell protoplasm is constructed Hence, 1 Sur une Fonction peu connue du Pancreas: La digestion des aliments azotes. Paris 1857-58. 3 Verdauung der Eiweisskorper durch den pankreatischen Salt Zeitschr. f. rat Med., 3d ser, Band 7, p. 17. 1859. 3 Virchow's Archiv, Band 25, p. 267. 1862. Ibid. Band 39, p. 130. 1867. 5 Proceedings of the Royal Society, vol 32, p. 20; On the Histology and Physiology of the Pepsin-forming Glands. as Heidenhain, Langley, and others have pointed out, ..