140 E. K. HOSKINS AND M. M. HOSKINS 



7. Gills 



The endothelium Hning the arterial arches and especially the 

 large sinuses in the gills is very phagocytic to injected trypan 

 blue and coarsely powdered carmine. It stores such substances 

 in concentration greater than that in any other cells examined, 

 and at the same time it proliferates and produces free phago- 

 cytes which circulate through the body. Such proliferation and 

 an abnormal amitosis occur after injection of excretory toxins, 

 which also seem to produce degeneration of these cells. There 

 is no indication that the gills are able to excrete solutions or 

 particulate matter into the water surrounding them. They are 

 probably a normal source of phagocytes for the circulation. 



8. Body wall 



The muscles, skin, and peritoneum had in general a negative 

 reaction to non-toxic solutions, vital dyes, and toxins. 



9. Vascular system 



The blood-vascular system reacted negatively to non-toxic 

 solutions so far as determined, except that sucrose in the blood 

 was inverted. Trypan blue and carmine were found in occa- 

 sional leucocytes and endothelial cells in the blood-vessels of the 

 kidney, digitiform gland, spiral valve, stomach, and body wall. 

 Endothelium lining the branchial and splenic sinuses and hepatic 

 sinusoids is very phagocytic toward trypa,n blue and carmine. 

 The arterial arches of the gills are lined with endothelium phago- 

 cytic to trypan blue. 



The lymphatics were not noticeably stained with vital dyes 

 up to five days, but the subject needs further study. 



Excretory toxins cause shght injury to the fixed endothelial 

 phagocytes, especially in the spleen and gills. They cause con- 

 gestion in all the organs especially in the kidney, digitiform 

 gland, and spiral valve. If injected intramuscularly they cause 

 slow degeneration of the erythrocytes, and if injected intra- 

 venously, sudden destruction of these cells. This destruction is 

 probably the cause of death in some cases of experimental 

 nephritis studied by other investigators. 



