1903.] 



Action of the Poison of the Hydrophidce. 



491 



destroyed the clotting power, and this, too, it must be remembered, 

 in spite of the Enhydrina poison being ten times as powerful as that 

 of the Cobra. It is evident, therefore, that the poison of the Enhy- 

 drina has no appreciable effect in ordinary dilute minimal lethal doses 

 on the coagulability of the blood, while, as a matter of fact, we have 

 already seen that such doses clo not produce any loss of the clotting 

 power of the blood. This was also the case when fifty times a 

 minimal lethal dose of the venom was injected into the vessels of 

 rabbits with the result of causing death in about six minutes. 



The above experiments show that the poison of the Hydrophidse 

 has no appreciable action on the blood of animals, which can in any 

 way account for the symptoms and fatality caused by it, yet it kills 

 with precisely the same symptoms as are produced by Cobra venom, 

 and, as we shall see presently, there are good reasons for believing 

 that it has a special action on the nervous system. It will be evident at 

 once that this furnishes a very strong argument in favour of the view 

 that Cobra venom also kills through the nervous system, as held by 

 Lauder Brim ton and Fayrer, and not through the blood, as maintained 

 by Cunningham. It is also of special interest to observe that although 

 the action of the poison of the Hydrophiclse on the blood is practically 

 a negligible quantity in its lethal effects, yet it still persists to a slight, 

 but easily demonstrable, degree ; for if it so persists in the Sea-snake, 

 it may also persist in a still greater degree in the case of the Cobra 

 without being a very active agent in the lethal effects produced by 

 that poison, which kills through the nervous system as does that of 

 the Hydrophidse. In this connection it is interesting to observe that all 

 through the poisonous snakes we find evidence of an action on the blood 

 and on the nervous system in different degrees. Thus, beginning with 

 the Viperine snakes, we first have the Vipera Eussellii, which appears 

 to be the purest blood poison of the known venomous snakes, killing by 

 producing intravascular clotting in large closes, and the opposite effect 

 of total loss of coagulability in repeated sub-minimal lethal ones. Then 

 we come to the class of Pit-vipers, of which the rattlesnake of America 

 has been most closely investigated by Weir Mitchell and Eeichert. 

 They also found a very marked effect on the blood, apparently 

 similar to that produced by the Daboia, but, combined with this, we 

 have a marked paralytic effect on the nervous system, and especially 

 on the respiratory centre, for the authors mentioned conclude that 

 although death may occur through the effect on the blood, yet they add 

 " There can be no question, however, that the respiratory centres are 

 the parts of the nervous systems most vulnerable to the poison, and 

 that death is commonly due to their paralysis." Leaving the Viperine 

 snakes and passing on to the poisonous Colubrines, we first come to 

 the Australian species, so ably studied by C. J. Martin, namely, 

 the Pseudechis, and we find again a combination of the two effects to 



