124 E. R. HOSKINS AND M. M. HOSKInS 



e. Spiral-valve. In the first two animals in which the bile 

 (presumably containing the toxin) was allowed to enter the gut, 

 the spiral valve showed approximately the same amount of 

 injury as in the chromate and tartaric experiments. In the 

 third animal in which the bile was kept out of the intestine the 

 injury is less extensive than in the others, although there is 

 some congestion of the mucosa and desquamation of its surface 

 epithelium. This was true also of other animals which were not 

 examined microscopically, as stated above (4). 



/. Stomach. The stomach in the first two animals resembles 

 that in the chromate experiments. In the third, the stomach is 

 practically normal, and the very few alterations observed might 

 be postmortem in origin, or the result of vascular injury which 

 causes cell inanition. 



g. Postvalvular intestine. That portion of the intestine 

 posterior to the spiral valve was examined microscopically in the 

 second animal, and is entirely normal in appearance, although 

 the spiral valve which empties into it is seriously injured. Its 

 epithelium is stratified while that of the spiral valve is simple 

 columnar. 



h. Gills. The gills of the first animal were examined and 

 show some signs of injury. In the sinuses at the base of the 

 filaments the endothelial cells have rounded as they do when 

 granules are injected. Here are seen many peculiar nuclei 

 (fig. 27) such as were seen in the spleen and kidney, some of 

 which may be found priDtruding from the endothelium. The 

 endothelial cells in places are full of dull granules which have 

 come originally from the blood, or else are formed in the cells by 

 degeneration. Many free cells are to be found in the sinuses^ 

 indicating a proliferation of the endothelium. 



DISCUSSION 



1. Digitiform gland 



The digitiform gland reacted somewhat as an excretory organ, 

 but it is not very efficient as .such. In this it resembles the 

 kidney. Its normal secretion collected from three adult dogfish 



