REACTION OF SELACHII TO INJECTIONS 139 



body definitely proven in our experiments as able to excrete 

 particulate matter. It is stained deeply by such substances. 

 The liver contains a great deal of normal pigment which is 

 excreted in the bile in the same way that injected pigments are 

 excreted, thus demonstrating that the latter act is a normal 

 process. 



Excretory toxins are probably excreted by the liver and they 

 cause very little injury to this organ. When the kidneys were 

 almost entirely destroyed, the liver showed slight injury to 

 about 12 per cent of the nuclei, which were hyperchromatic 

 and slightly shrunken, and in the bile ducts there was more 

 than the usual amount of granular substance, probably degen- 

 erated cytoplasm. The vessels of the liver are discussed below. 



4. Spleen 



The spleen is very well adapted for phagocytic activity, and is 

 stained deeply by injected insoluble dyes. Injected particles 

 produce leucocytosis. Toxins cause congestion in the spleen, 

 the endothelium appears to be injured, very pecuharly shaped nu- 

 clei may be produced, and many nuclei become hypochromatic. 



5. Spiral valve 



The spiral valve has previously been considered to possess 

 excretory function and may have such function for certain 

 dissolved substances, but not all solutions we injected could be 

 recovered in the intestine and none of the dyes were taken up by 

 the epithelium. Excretory toxins pass through this epithelium 

 and destroy it, although they do not injure the intestine imme- 

 diately anterior or posterior to the spiral valve. We believe with 

 Denis ('13) that the spiral valve has some excretory function. 



6. Stomach 



A few injected solutions were recovered from the stomach, 

 but we do not believe that this organ has an excretory function. 

 Excretory toxins do not injure it directly and vital dyes do not 

 stain its epithelium. 



