THE GASTKIC JUICE. 215 



outs of the gastric juice probably acts on food, we shall 

 arrive at the conclusion, that the digestive property is not 

 dependent on the free acids alone, or on the animal principle 

 pepsine alone, but is resident in both. Thus, if a certain 

 quantity of gastric juice, in which some meat is being arti- 

 ficially digested, be neutralized with alkalies, the process is 

 immediately arrested. On the other hand, gastric juice 

 which has been boiled loses this property by the coagulation 

 of pepsine. Gastric juice does not act on all the principles 

 of food. Although helping, as we shall afterwards see, in 

 the digestion of solid fats and starchy matter, it does not 

 itself exert any important action on them ; it is essentially 

 the solvent of the albuminoid or nitrogenous constituents of 

 food. 



When muscular tissue is subjected to the action of the 

 gastric juice, it swells up, becomes soft, and the transverse 

 striae or markings on the muscular fibres disappear. Liquid 

 albumen is first precipitated in a floculent state by the 

 gastric juice, the precipitate undergoing a process of solution 

 afterwards. Casein also, when taken into the stomach, is 

 immediately coagulated, the little solid masses thus formed 

 in it gradually dissolving in the gastric juice, forming a 

 homogenous and slightly opaque liquid. Gluten, when 

 macerated in gastric juice, out of the body, has been 

 observed to break up into molecular matter, which falls to 

 the bottom of the vessel containing it. This change is pro- 

 bably only the first of a series which takes place in the body. 

 Gelatine is easily dissolved in the stomach, and its solu- 

 tion does not solidify on cooling. Bones are also dissolved 

 by the gastric juice. 



Whatever the substances dissolved, they are reduced to a 

 state of minute division, and form a substance possessing 

 certain peculiar properties, and to which the name of 



