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.

Date:
1880
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 Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    minoid matter of the ferment may be said to become charged, at the moment of elaboration by the gland- cells, with potential energy of a special kind—in the same way that a piece of steel becomes charged with magnetism by contact with a pre-existing magnet. The potential energy of the ferment is changed into the active form {i.e. becomes kinetic) when it is brought into contact with the alimentary substance on which it is designed to act. The chemical and physical characters of the digestive ferments appear to be tolerably uniform. In composition they resemble proteid substances, and contain carbon, oxygen, hydrogen, and nitro- gen in the same or somewhat similar centesimal proportions as albumen. But as not one of them has yet been obtained in a state of absolute isola- tion and purity, this is, strictly speaking, a matter of inference rather than an ascertained fact. They are all soluble in water; they are all diffu- sible, though with difficulty, through animal mem- branes and parchment paper. They are also capable (all those I have tried) of passing through porous earthenware by filtration under pressm^e; but some of them pass through readily, and others with the utmost difficulty and only in the smallest propor- tions. They are precipitated from their watery solutions by absolute alcohol—but unlike other proteids (peptones excepted) they are not truly coagulated by alcohol. When the alcohol is removed the