FORMATION OF HYDROCHLORIC ACID IN THE FOVEOL/E. 22J 



THE PRUSSIAN BLUE REACTION. 



This was first employed by Claude Bernard ('59) in his classic 

 experiment. A translation of his account is as follows: "In a 

 rabbit which had eaten very little there was injected into the 

 jugular vein a solution of lactate of iron and then a solution of 

 prussiate of potassium; both solutions were warm. Three quar- 

 ters of an hour afterward the animal was killed and at the autopsy 

 it was impossible to demonstrate the blue color in the tissue of 

 any organ. The urine, which was alkaline and cloudy, was not 

 blue, although it contained both prussiate of potassium and the 

 iron lactate, for it sufficed to add a few drops of hydrochloric or 

 sulphuric acid to cause the blue color of Prussian blue to appear 

 immediately. Upon opening the alimentary canal a blue color 

 was found on the surface of the mucous membrane of the 

 stomach and particularly on the part which corresponded to 

 the lesser curvature of that organ. But this blue was quite 

 superficial; the little deposits of Prussian blue were only on the 

 surface of the mucous membrane, and a microscopic examination 

 did not reveal any Prussian blue in the gastric glands." 



Later, Claude Bernard ('77) said: "The acid of the gastric 

 juice is formed only after the secretion of the juice, the glands 

 secreting a liquid which breaks up into an acid fluid and another 

 product as yet not definitely determined." 



The results which we have to report indicate that the decision 

 reached by the great French physiologist is correct. 



The Prussian blue reaction was employed also by Lepine ('72) 

 in dogs. He used potassium ferrocyanide with lactate of iron or 

 sulphate of iron. He was unable to obtain Prussian blue in any 

 cells of the gastric gland either by injection, maceration, or by 

 passing the salts through a dialyzing membrane made of the 

 gastric mucous membrane, although by the latter method he did 

 obtain a little blue in a lymphatic space of the connective tissue 

 between the glands. He concluded that the acid was not formed 

 as such within the gland. 



Sehrwald ('89) put pieces of the gastric mucous membrane 

 into a solution of lactate of iron for one day and later into a 

 solution of potassium ferricyanide. He believed that in this 

 way he would obtain a deposit of Prussian blue at the seat of 



