REACTION OF SELACHII TO INJECTIONS 135 



6. Stomach 



A few solutions and one granular dye were recovered in the 

 stomach, but the possibility of regurgitated bile was not elimi- 

 nated as should have been done. Weed's Prussian blue was 

 not deposited in the epithelium of the stomach nor were any of 

 the injected dyes. The excretory toxins caused slight conges- 

 tion of the stomach in some cases and in a few specimens the 

 surface epithelium stained poorly. A small amount of cytolysis 

 was present in some cases, but the slight damage noted in the 

 stomach might have been done by toxin regurgitated from the 

 intestine or by cell inanition resulting from vascular injury. 

 Regurgitation is often observed. 



Cecil- Weil ('17) found that after injection of Congo-red into 

 patients with gastric ulcers it could be recovered in the stomach 

 contents, but they admitted the fact that it is excreted in the 

 bile and they did not eliminate the possibility of regurgitation 

 of bile into the stomach. The stomach in selachians appar- 

 ently is able to excrete only a few injected solutions, and is 

 probably not normally an excretory organ of any importance, 

 if it has this function at all. 



7. Gills 



In the experiments with non-toxic solutions the gills were 

 examined in only those animals receiving Weed's solution. In 

 these specimens Prussian blue was found in the blood-vessels 

 of course, but there was none in the epithelium covering the 

 gills nor in the connective tissue. This argues against the 

 theory that the gills can excrete solutions. Since the gills are 

 bathed by the isotonic sea-water, it would seem natural that 

 solutions might diffuse into it from the branchial vessels, but we 

 have no evidence that this occurs. 



Granular dyes are ingested freely by the endothelium which 

 lines the sinuses that are interposed between the arterial arches 

 and the capillaries in the gill filaments. It is also ingested by 

 the endothelium of the branchial arteries. In fact, in these 

 cells of the gill sinuses the phagocytic function seems to be 



