On the digestive ferments and the preparation and use of artificially digested food : being the Lumleian Lectures for the year 1880. Delivered before the Royal College of Physicians / by Wm. Roberts.

  • William Roberts
Date:
1881
Catalogue details

Licence: Public Domain Mark

Credit: On the digestive ferments and the preparation and use of artificially digested food : being the Lumleian Lectures for the year 1880. Delivered before the Royal College of Physicians / by Wm. Roberts. 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.

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    They are coagulated and rendered permanently inert by the heat of boiling water; and when in solution they are coagulated and destroyed by a heat of about 160 Fahr. (71 C). [There is a curious point in regard to the proteolytic ferments which requires elucidation. Liquid preparations of these fer- ments invariably contain a considerable amount of unchanged that is to say of undigested—albumen, which is precipitated by the addition of nitric acid or by boiling. This is the case both with pancreatic extracts and with solutions of pepsin acidulated with hydrochloric acid. It is evident that this sub- stance cannot be any one of the ordinary forms of albumen—■ otherwise it would long since have undergone digestion—it would in fact have been transformed into peptone by the tryp- sin or pepsin associated with it in the solution—and in that condition would of course have been incapable of being precipi- tated by nitric acid or boiling. All this leads up to the infer- ence that the albuminoid matter which constitutes the organic substratum of pepsin and trypsin is an altogether special form of albumen—and that one of its peculiarities is that it is unsus- ceptible of the proteolytic transformation which we call digestion. Its relation to ordinary albumens would resemble that of an unfermentable sugar in regard to ordinary sugars. It fm'ther sugo-ests itself to one's mind that the undigested remnant which is invariably found as a residuum in the artificial digestions of proteids—and which goes by the name of dyspeptone—is not, as has been thought, a bye-product of the digestive pro- cess, but that it is simply an admixture of this variety of non- digestible albumen.] Each digestive ferment has its special correlative alimentary principle, or group of principles, on which alone it is capable of acting. Diastase acts exclusively on amylaceous substances. Pepsin and trypsin act only on the azotised principles—the emulsive ferment of the pancreas is only capable of acting on fatty bodies—the inversive ferment of the small intestine has no activity except on cane-sugar. The changes impressed on alimentary principles by the di- gestive ferments are not, chemically speaking, of a profound character—and they affect much more the physical state of these principles than their chemical composition. In the main
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