272 VENOMOUS SNAKES AND THE PHENOMENA OF THEIR VENOMS 



they contain can not be without marked action in some cases. These venoms 

 may, therefore, cause death either through a destructive local action or through 

 the operation of the neurotoxin upon the central nervous system. 



In the case of cobra venom, the toxic action must be ascribed to neurotoxin. 

 There the local effects are almost nil, while the respiratory disturbances are very 

 apparent. The poisoned animals suffer from dyspnoea and from motor paralysis. 

 Among fishes cobra venom causes rapid loss of equilibrium, so that the venomized 

 animal swims with a rotary motion until it becomes too weak to struggle further. 

 Crotalus and moccasin venoms cause far less disturbance of equilibration, while, on 

 the other hand, their action at the beginning is likely to be irritative; the animal 

 dashes about furiously without exhibiting evidence of a marked loss of balance. 



Speaking generally, cobra venom is most toxic and crotalus venom least toxic 

 for cold-blooded animals. Moreover, this rule applies to the different classes as 

 well as to the various species of animals employed. In other words, cold-blooded 

 animals are more highly susceptible to the toxic action of neurotoxin than to that 

 of htemorrhagin.^ Crotalus venom is effective chiefly in those instances in which 

 the local lesions are marked; while in instances in which it acts independently of 

 the local lesions a far larger dose, in keeping with its small proportional content 

 of neurotoxin, is required to produce fatal results. 



Snakes and frogs succumb easily to cobra venom, but they are relatively insus- 

 ceptible to crotalus and moccasin venoms. They would seem to be entirely resist- 

 ant to the action of haemorrhagin. Turtles are more susceptible to all venoms 

 than the foregoing animals, and fishes exceed turtles in this respect. The grass- 

 hopper succumbs only to large doses of venom. Among the crustaceans the horse- 

 shoe crab is almost insusceptible, and other species of crabs are only moderately 

 susceptible to venom poisoning. The lobster is only moderately resistant. 



Excepting the earthworm, all the worms with which I experimented showed 

 a low degree of susceptibility. While the first will die in toto if injected with venom, 

 the others show at times general effects, but they suffer only partial necrosis, from 

 which they finally recover. After separation of the dead parts the worms seem to 

 have been entirely restored. On the injection of Phascolosoma with an enormous 

 dose of venom I have seen the muscular contractibility of the injected part disappear 

 for a period of a week or longer, but in the end it was recovered. If necrosis 

 occurred a slough was formed and was finally cast off. 



Upon echinodermata venoms produce little effect. The sea-urchin succumbed to 

 all the venoms, while star-fish and sea-cucumbers were not perceptibly affected. 



The general toxicity of venoms upon the adult organism, as compared to their 

 special effects which are produced upon the embryological elements ^ of the same 

 species, is of considerable interest. The ova or spermatozoa of some vermes and 

 echinodermata are easily dissolved or fragmented by venoms, while the adults of cor- 

 responding species are almost entirely insusceptible to them. On the other hand, the 

 reverse is possible. Thus the eggs of Fundidus — a fish — are comparatively insus- 

 ceptible to venoms, as they can be fertilized in sea-water containing rather a large 

 amount of venoms and development of the fertilized ova progresses in the normal 

 way, but the adults are found to be highly susceptible to the same kind of venoms. 



A close examination as to the relation existing between the general toxicity and 

 the haematoxic power ^ of venoms upon cold-blooded animals adds further interest- 

 ing as well as important facts to the understanding of the nature of the action of snake 

 venom in vivo. 



1 Flexner and Noguchi. The constitution of snake venom and snake sera. Journal of Pathology 

 and Bacteriology, 1903, VIII, 396. 



* Flexner and Noguchi. On the plurality of cytolysins in snake venom. Univ. of Penna. Medical 



Bulletin, 1903, July-August. 



• Noguchi. The effects of venom upon the blood of cold-blooded animals. Univ. of Penna. Medical 



Bulletin, 1903, July-August. 



