i86 BIOLOGY. [Book ii. 



make use to obtain the necessary gastric ferment. M. Schiff, 

 who has occupied himself a great deal with these artificial diges- 

 tions, employs often the stomach of animals which are not 

 ruminants.^ In that cases he detaches only the median por- 

 tion, called peptic ; he infuses it in from 500 to 600 grammes of 

 acidulated water, and lets it rest for five or six days. The liquid 

 thus obtained has the property of transforming the albuminoidal 

 aliments into peptones isomerical, but soluble in water and even 

 diluted alcohol, moreover incoagulable by heat, and no longer 

 forming insoluble compounds with the metallic salts. In addition, 

 when these peptones are mingled with sugar, they, as we have 

 already maintained, mask the reaction of Ttommer. 



All the processes of absorption which we have just enumerated 

 enable us surely to demonstrate that the only aliments trans- 

 formed by the gastric juice are the albuminoidal substances. The 

 stomach absorbs besides a number of other substances contained 

 in the aliments, but on condition that they are soluble in acidu- 

 lated water, for the stomach does not modify them (salts, and so 

 on). The fat bodies, starch, are scarcely altered by the gastric 

 juice ; they pass with the chyme into the intestine, where, more- 

 over, the transformation of the protei'c substances saturated with 

 gastric juice is gradually finished.^ 



According to M. SchifF,^ and in opposition to an idea generally 

 received, the liquid albumine is more slowly digested than the 

 solid albumine ; it demands more acid for its transformation. 

 Moreover the stomachal acid is incapable of coagulating albu- 

 mine. 



On the contrary, liquid caseine is promptly coagulated by the 

 gastric juice, and its previous coagulation is even a condition of 

 its transformation into peptones. 



Vegetal legumine dissolves without difficulty in the acids, and 

 is afterwards transformed. 



' M. Schiff, loc. Hi., t. I., p. 78. 



' M. Schiff, loc. eU., t. II., pp. 123, 124. 



3 Ibid. t. II., p. 150. 



