110 POWER OF ANIMAL MEMBRANE 



contact with it for a time at the temperature of 

 the body, caused these substances to lose the solid 

 form and to dissolve in the liquid. 



9. It can hardly be doubted that the substance 

 which is present in the gastric juice in a state of 

 change is a product of the transformation of the 

 stomach itself. No substances possess, in so high 

 a degree as those arising from the progressive de- 

 composition of the tissues containing gelatine or 

 chondrine, the property of exciting a change in the 

 arrangement of the elements of other compounds. 

 When the lining membrane of the stomach of any 

 animal, as, for example, that of the calf, is cleaned 

 by continued washing with water, it produces no 

 effect whatever, if brought into contact with a solu- 

 tion of sugar, with milk, or other substances. But 

 if the same membrane be exposed for some time 

 to the air, or dried, and then placed in contact with 

 such substances, the sugar is changed, according to 

 the state of decomposition of the animal matter, 

 either into lactic acid, into mannite and mucilage, 

 or into alcohol and carbonic acid ; while milk is 

 instantly coagulated. An ordinary animal bladder 

 retains, when dry, all its properties unchanged ; but 

 when exposed to air and moisture, it undergoes a 

 change not indicated by any obvious external signs. 

 If, in this state, it be placed in a solution of sugar 

 of milk, that substance is quickly changed into 

 lactic acid. 



10. The fresh lining membrane of the stomach of 



