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 hemorrhagin.' 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 hemorrhagin. 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 zm 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 tothem. On the other hand, the 
reverse is possible. ‘Thus the eggs of Fundulus —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 hzematoxic 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. 
2 Flexner and Noguchi. On the plurality of cytolysins in snake venom. Univ. of Penna. Medical 
Bulletin, 1903, July-August. 
3 Noguchi. The effects of venom upon the blood of cold-blooded animals. Univ. of Penna. Medical 
Bulletin, 1903, July-August. 
