REACTION OF SELACHII TO INJECTIONS 133 



necessarily portray normal functions, because their experiments 

 place their animals under abnormal conditions. 



Excretory toxins usually caused congestion of the liver, but 

 not serious injury to the parenchyma. We did not prove abso- 

 lutely that the toxins passed through the liver into the bile, but 

 we believe that they did so because all the other solutions and 

 suspensions were recovered in the bile, and because the liver 

 itself was injured by the toxins. Tests were made for uranium 

 nitrate, but the green color of the bile prevented our determining 

 whether the injected toxin was present or not. Injury to the 

 liver was indicated by relatively few hyperchromatic shrunken 

 nuclei and an increased amount of granular debris in the bile 

 ducts. In none of the sections examined did more than 12 per 

 cent of the nuclei appear injured. If the liver is able to elimi- 

 nate excretory toxins, as it probably does, and without serious 

 injury to itself, we must agree with Denis ('13) that this helps 

 explain why dogfish are able to withstand large doses of such 

 poisons. 



4- Spleen 



The spleen in the experiments with Weed's solution was seen 

 to be impregnated with Prussian blue granules. This indicates 

 that the vessels open directly into the pulp or else that the endo- 

 thelium is very permeable to solutions because relatively more 

 Prussian blue was found in this organ than in other non-excre- 

 tory organs. The spleen of the dogfish seems to be very well 

 adapted for phagocytic activity, although Wislocki ('17) believes 

 that such is not the case in bony fishes. 



Injected granules of dyes are taken up very quickly by the 

 spleen which thus becomes deeply stained. In this respect it is 

 equaled only by the liver. Injection of particulate matter was 

 followed by a leucocytosis, and the number of mitotic figures 

 seen in such cases is greatly increased. 



Toxins caused congestion in the spleen in most specimens. 

 In one uranium nitrate experiment there were present in the 

 spleen a very large number of peculiar-shaped nuclei. These 

 are found only occasionally in the other specimens. They 



THE JOURNAL OF EXPERIMENTAL Zo50LGY, VOL. 27, NO. 2 



