GASTRIC JUICE. 33 



of the most remarkable of its properties is that its digestive 

 powers vary according to the medium in which it is contained. 

 In the gastric juice, which is acid, it dissolves nitrogenous mat- 

 ters, such as fibrin, gluten, and albumen ; but exerts no action on 

 baked starch ; but if the gastric juice is rendered alkaline by 

 the addition of a little carbonate of soda, it rapidly dissolves the 

 starch, and no longer possesses the power of acting on the 

 nitrogenous matters. As these physiological properties are 

 exactly those of saliva and the pancreatic fluid, it became an in- 

 teresting point to ascertain if a change in the reaction of these 

 fluids would cause a corresponding variation in their solvent 

 power. This was found to be the case ; on acidulating these 

 naturally alkaline fluids, their ordinary mode of action was in- 

 verted, and they were enabled to dissolve nitrogenous matters, 

 while their capability of dissolving starch was lost. From nu- 

 merous and varied experiments they believe that one and the 

 same organic principle (the agent of digestion) exists in the 

 gastric juice, the pancreatic fluid, and the saliva, and that its 

 physiological action varies according to the acid or alkaline 

 nature of the fluid in which it occurs. 



M. Melsens 1 has also examined the gastric juice, and denies 

 the accuracy of Blondlot's conclusions.] 



The fluid secretion in the crops of birds is stated by Gmelin 

 and Tiedemann to have an acid reaction ; and the fluid in the 

 glandular stomach, even when empty, contains free acids, es- 

 pecially muriatic and acetic acids. 



Brugnatelli observed that Iceland spar inclosed in tubes is 

 decidedly attacked after remaining for some time in the stomachs 

 of hens and turkeys ; and Treviranus noticed that a porcelain 

 basin, in which the chyme of hens had been digested, was cor- 

 roded, from which he concluded that fluoric acid was present. 

 Tiedemann and Gmelin did not succeed in detecting fluoric 

 acid in the gastric juice of ducks, although they carefully sought 

 for it. 



Morbid Gastric Juice. 



It is well known that the gastric juice sometimes assumes 

 anomalous characters, but important as such modifications are 



1 Journal de Pharmacie, Jan. 1845. 

 ir. 3 



