STOMACHAL DIGESTION. 239 



(albuminoids). The salts chiefly found in it are phosphate 

 of soda, and chloride of sodium. 



In order to study the properties of the gastric juice, this 

 fluid is procured through a fistulous opening in the stomach, 

 generally of a dog. Blondlot, of Nancy, 1 was the first to 

 employ this method, which has since yielded such valuable 

 results in the hands of Cl. Bernard and Schiff. 



The organic (albuminoid) matter contained in the gastric 

 juice is a sort of ferment called pepsin or gasterase: this 

 lerment is of a soluble nature, like that of the saliva (ptya- 

 line). Its existence was first pointed out by Schwann; 

 Payen obtained it by precipitation from the gastric juice by 

 alcohol ; in this way, pure pepsin may be produced, pre- 

 senting, after desiccation, the appearance of a white powder : 

 it is often adulterated for purposes of trade by being mixed 

 with starch. Pepsin exhibits all the reactions of albuminoid 

 substances, though its albuminoid nature (Brucke), as well as 

 that of ptyaline (Cohnheim), has been denied. (See Hitter, 

 op. cit.). It acts on the albuminoid substances of ali- 

 ments by transforming them into albuminose or peptone, 

 which is an isomeric form of albumen, and can neither be 

 precipitated by heat nor by acids, and is readily absorbed. 



The presence of an acid is necessary for this transforma- 

 tion, which essentially constitutes the digestive function of 

 the stomach ; in the gastric juice therefore pepsin is united 

 with an acid in a free state; the exact nature of this acid 

 has been much disputed, but it has been proved by artificial 

 digestion that, whatever it may be, the effect produced by it 

 is always the same. Some maintain that in the normal gas- 

 tric juice, this element is represented by hydrochloric acid 

 (Prout, Schmidt, Mulder, Brinton, Rouget, Hitter, etc.) ; 

 others, by phosphoric acid (acid phosphate of lime, Blond- 

 lot) ; and others still, by lactic acid (01. Bernard, Barres- 

 will) : the latter opinion is now most generally held. 



It must be admitted that the arguments which have 

 decided physiologists in favor of the existence of different 

 acids have all some foundation, but may all be more or less 

 completely refuted, and that organic chemistry seems, up to 



especially about the region of the pylorus. Sappey has, however, 

 shown that these supposed closed follicles are only tubular glands, 

 of which the excretory canal is obliterated, and which develop in 

 the form of a small spherical cyst. (See " Anat. Descriptive," 

 Vol. IV., p. 187.) 



1 Blondlot, " Traite Analytique de la Digestion. " 1843. 



