GASTRIC JUICE. 221 



Organic Constituent of the Gastric Juice. Pepsine is an organic nitro- 

 genized substance, which is peculiar to the gastric juice and essential to its 

 digestive properties. When the gastric fluid was first obtained, even by the 

 imperfect methods employed anterior to the observations of Beaumont and 

 of Blondlot, an organic matter was spoken of as one of its constituents. 



Experiments on artificial digestive fluids, by Eberle, Schwann and Miil- 

 ler, Wasmann and others, have demonstrated that acidulated extracts of the 

 mucous membrane of the stomach contain an organic matter, first isolated by 

 Wasmann, on which the solvent powers of these acid fluids seem to depend. 

 Mialhe, who has obtained this substance in great purity by the process recom- 

 mended by Vogel, described the following properties as characteristic of the 

 organic matter in artificial gastric juice : Dried in thin slices on a plate of 

 glass, it is in the form of small, grayish, translucent scales, with a faint and 

 peculiar odor and a feebly bitter and nauseous taste. It is soluble in water 

 and in a weak alcoholic mixture, but is insoluble in absolute alcohol. A 

 solution of it is rendered somewhat turbid by a temperature of 212 Fahr. 

 (100 C.), but it is not coagulated, although it loses its digestive properties. 

 It is not affected by acids but is precipitated by tannin, creosote and a great 

 number of metallic salts. This substance dissolved in water slightly acidu- 

 lated possesses, in a very marked degree, the solvent properties of the gastric 

 juice ; but it has been found by Payen and Mialhe not to be so active as the 

 substance extracted from the gastric juice itself, which is described by Payen, 

 under the name of gasterase. In the abattoirs of Paris, Mialhe collected 

 from the secreting stomachs of calves as they were killed, between six and 

 ten pints (2*8 and 4-7 litres) of gastric juice ; and from this he extracted the 

 pure pepsine by the process recommended by Payen, which consists merely in 

 one or two precipitations by alcohol. This substance he found to be identical 

 with the substance obtained by Payen from the gastric juice of the dog. Its 

 action upon albuminoid matters was precisely the same as that of pepsine 

 extracted from artificial gastric juice, except that it was more powerful. 



Free Acid of the Gastric Juice.. The character of the free acid of the 

 gastric juice has long been a question of uncertainty and dispute. In former 

 editions of this work, the different views of chemists with regard to the nature 

 of this acid were fully discussed. It may now be stated that almost all physi- 

 ologists adopt the view that the gastric juice contains free hydrochloric acid, 

 with possibly a very small quantity of lactic acid. It is admitted, however, 

 that the degree of acidity of the gastric juice is variable, and that the normal 

 acid may be replaced, without loss of the digestive properties of the fluid, by 

 lactic, oxalic, acetic, formic, succinic, tartaric, citric, phosphoric, nitric or 

 sulphuric acid. 



Saline Constituents of the Gastric Juice. It has been shown that 

 artificial fluids containing the organic matter of the gastric juice and the 

 proper proportion of free acid are endowed with all the digestive properties 

 of the normal secretion from the stomach, and that these properties are 

 rather impaired when an excess of its normal saline constituents is added or 

 when the relation of the salts to the water is disturbed by concentration. 

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