130 E. R. HOSKINS AND M. M. HOSKINS 



The effects of excretory toxins on the kidney in dogfish are 

 somewhat the same as in mammals, as described by Ophuls 

 ('08, '11), Schlayer-Takayasu ('09), Suzuki ('12), Pohl ('12), 

 Dickson ('12), Christian-O'Hare ('13), Underhill-Blatherwick 

 ('14), Potter-Bell ('15), Tribe-Hopkins-Barcroft (16), and 

 various others who administered potassium chromate, tartaric 

 acid, and uranium nitrate. Denis ('13) noted that dogfish can 

 withstand many times as much potassium chromate and ura- 

 nimn nitrate as will kill a mammal, and we can add tartaric 

 acid to the list. One of our fish which received 200 mg. per kg. 

 body weight of uranium nitrate lived for eighty hours. In 

 extreme cases the dogfish kidney shows nearly complete destruc- 

 tion of the tubules by these poisons. The blood-vessels usually 

 are not noticeably injured, but severe congestion occurs. The 

 glomeruli, as in mammals, are injured only slightly when at all. 

 Three distinct types of degenerative processes in the tubules are 

 produced by all three of the toxins used. The deposit of hyaline 

 substance in renal tubules in mammals after injection of tartaric 

 acid was noted by Underhill-Blatherwick, and Christian-O'Hare 

 found it in blood-vessels after uranium poisoning. Granular 

 degeneration is probably a constant type in all such experi- 

 ments, and hydropic degeneration usually but not always occurs 

 with it. In our specimens there is some vacuolization in the 

 cells showing the former type of degeneration, but some cells 

 undergo cytolysis without first passing through granular change. 

 The reason for these three different kinds of degeneration is not 

 apparent. All three types were present in the same animal in 

 some of the experiments and often two could be seen in a single 

 tubule. They are not simply different steps in one and the same 

 process as a study of the accompanying figures easily shows. 

 In the hyaline type a definite new substance is formed. There 

 are two distinct types of nuclear degeneration in our experi- 

 ments with nephritis and they are exactly opposite in nature. 

 In one type the nucleus absorbs v/ater, swells to two or three 

 times its normal size, and the nuclear substances gradually go 

 into solution, while in the other type the nucleus becomes opaque 

 and shrinks until it completely disappears. This shrinkage is 



