236 B. C. H. HARVEY AND R. R. BENSLEY. 



Fifth, is the occasional presence of Prussian blue in the gland 

 lumen and in the canaliculi of the parietal cells due to backing 

 up of the blue precipitate from the foveolae or from the surface of 

 the mucous membrane.? 



In order to determine this question many experiments were 

 made with Prussian blue, with carmine and with India ink. 

 Hydrostatic pressure, dialysis, and positive pressure by a syringe 

 piston against a piece of gastric mucous membrane tied over the 

 end of the syringe were employed. The results were all nega- 

 tive, thus confirming those of Lepine ('7 2 )- 



Prussian Blue Reaction in Animals which Have no Parietal 

 Cells, but Secrete Acid. Sixth, where does the Prussian blue 

 reaction occur in animals which have no parietal cells but yet 

 secrete acid? 



The experiment above reported with the fowl showed that 

 the Prussian blue occurred in the lumen of the depression receiv- 

 ing the secretion of the compound glands of the proventriculus. 

 It was not found in the gland cells. It appeared between the 

 cells of the surface epithelium immediately adjacent to the 

 opening of the depressions. As above stated, it occurred also 

 in many other places. 



A snapping turtle was given one half gram each of sodium 

 ferrocyanide and iron and ammonium citrate in dilute solution 

 three times daily during four days; the solutions were given 

 separately and subcutaneously in the inguinal region. Two 

 small fish were shoved into the stomach with a glass rod and were 

 found there later partially digested. On the fourth day the 

 animal was killed and the stomach examined. A deposit of 

 Prussian blue was found in every cell of the somewhat coarse 

 foveolae of the gastric gland. In these cells it occupied a definite 

 position, the same in each cell. Each cell contained a mucous 

 plug which occupied the half of the cell next the lumen, under 

 it a small spherical mass of Prussian blue, and under that the 

 nucleus. The mass of Prussian blue was nearly as large as the 

 nucleus. Sections through these foveolse stained with paracar- 

 mine or mucicarmine presented a very pretty appearance 

 because of the extreme regularity of the position of the nuclei, 

 the little masses of Prussian blue and the mucous plugs. There 



