FORMATION OF HYDROCHLORIC ACID IN THE FOVEOL.^. 245 



nation of this system. We have also obtained a feeble reaction 

 by means of intravenous injection of solutions of naphtol blue. 



CONFIRMATORY TESTS. 



In view of the results obtained with cyanamin chloride it 

 seemed probable that, other dyes closely related to this substance 

 would give similar reactions, and accordingly we prepared by 

 acting on naphtol blue with anilin, according to the method 

 described by Nietzki and Bossi ('92), the closely related dye 

 named by the former phenylated nile blue. Solutions of this 

 dye gave by far the most striking results obtained inasmuch as 

 the intensely red base was precipitated in the canaliculi of the 

 parietal cell, while the secretion in the gland lumen was stained 

 a bluish red color. Similar results were obtained with solutions 

 of nile blue sulphate, but a less pronounced reaction was obtained, 

 the content of the parietal cells staining in this case bluish red, 

 that of the lumina of the glands blue. 



Neutral red, which has been highly commended by Ehrlich 

 as an indicator for biological studies, next suggested itself in this 

 connection for we had long known that it stained the secretion 

 in the gastric glands and in the parietal cells. This dye may 

 be used like cyanamin by immersing the fresh mucous membrane 

 in a I in 10,000 solution in normal salt solution or by injecting 

 such a solution of the dye through the blood vessels. In neutral 

 solutions neutral red possesses a reddish color with a suggestion 

 of orange.- Alkaline solutions precipitate the base in the form 

 of a yellow precipitate while acid solutions produce a crimson 

 color. This dye therefore is capable of indicating either acidity, 

 alkalinity or neutrality. In preparations made as indicated 

 above of the fresh actively secreting fundus mucous membrane 

 of the stomach neutral red promptly stains the secretion in the 

 canaliculi of the parietal cells and in the main lumen of the 

 gland. In the parietal cells the color assumed is the unmistakable 

 yellow of the free base, in the lumen of the gland the color 

 approaches more closely to the neutral tint, while the short 

 diverticula of the lumina which connect the parietal cell with the 

 lumen are of an intermediate tint. The whole system, however, 

 is without question on the alkaline side of the reaction with 



