488 



Dr. L. Rogers. On the Physiological 



[Mar. 31, 



Effect of the Poison on other Cold-blooded Animals. 



I have not yet been able to test any extensive series of other cold- 

 blooded animals to see if they are equally susceptible to the poison of 

 the Hydrophidae as fish are, but in one instance a frog weighing 

 30 grammes was injected with a dose of - 2 milligramme per kilo, 

 with the result that it showed well-marked symptoms of paralysis, but 

 eventually recovered, so that it would appear to have been about as 

 susceptible as fish. Some harmless snakes were injected with note- 

 worthy results. Thus, two specimens of the Coluber fasciolatus were 

 injected with doses of 10 and 50 grammes per kilo respectively, with 

 the poison of the Enhydrina, with no ill effect, and the former received 

 a second dose of 50 milligrammes per kilo three days after the smaller 

 dose, equally without effect. Here we have a harmless colubrine snake 

 withstanding 100 times the fatal close for a fish and 1000 times that 

 for a warm-blooded animal. Further, two specimens of the harmless 

 green Whip-snake {Dryophis mycterizans) were tested, but in this species 

 25 milligrammes per kilo in one instance, and 15 in the other, each 

 produced death in less than two hours, so that a smaller dose would 

 nearly certainly have been fatal. This opens up a large question 

 which must await further investigation. 



The Physiological Action of the Poison on the Blood. 



The striking similarity of the symptoms produced by the poison of 

 the Hydrophiclae and by Cobra venom leads one to expect a similarity 

 of action on the blood. The researches of Cunningham have shown 

 that Cobra poison has a very marked power of dissolving the red 

 corpuscles of the blood and also in reducing its coagulability, and, 

 •contrary to the views of Lauder Brunton and Fayrer, he holds that 

 these blood changes are the essential features of the action of the 

 poison, and not its action on the nervous system, as held by the latter- 

 authors. Experiments have been carried out to test the effect of the 

 poison of the Hydrophidse on the blood, with unexpected and im- 

 portant results. Taking first the poison of the Enhydrina, with which 

 most of the observations have been made, and remembering that it is 

 ten times as potent for warm-blooded animals as is Cobra venom, we 

 may compare the action of the two poisons in dissolving the red cor- 

 puscles of the warm-blooded animals, the blood of pigeons and of the 

 human species having been used in the experiments. The method of 

 mixing the poison in different degrees of dilution with a minute 

 measured drop of blood, and counting the number of corpuscles with a 

 h£emocytometer before, and at varying periods after, the addition of the 

 venom was adopted. The poisons were always dissolved in isotonic 

 salt solutions, and equal quantities of blood in the same salt solution, 



