4 EFFECTS OF SNAKE VENOM. 



death was doubtful the experiment was repeated. In general, it may be stated that 

 the animals used in the experiments stood the necessary handling and captivity with- 

 out serious drawbacks. But in a few instances the degree of sensitiveness to these 

 procedures was found to be very great. Thus, in the case of several kinds of small 

 fish, e. g., pollack, silver-side, pipe-fish, this sensitiveness was so great that they did 

 not survive beyond 24 hours in captivity. Animals surviving the injections were, as 

 a rule, killed at the end of the experiment and examined for local and general lesions. 



The results of the study are given in tabulated form. 



In reviewing the tables, one is impressed with the wide degree of suscepti- 

 bility to snake venom exhibited by cold-blooded animals. On analyzing the effects 

 produced, it becomes quickly evident that cobra venom exerts little if any local 

 action, although it is the most toxic of all venoms employed. Crotalus venom, on 

 the other hand, while exhibiting the least general toxicity, displays the greatest 

 local action. Water moccasin venom occupies an intermediate position in this 

 regard. 



The chief local effect produced by rattlesnake and water moccasin venoms is the 

 escape of red blood corpuscles from the vessel ; only rarely is macroscopic necrosis 

 of tissue visible. This production of haemorrhage is, however, not restricted to the 

 site of injection of the venom, but in some animals generalized haemorrhages also 

 take place. This latter effect was noticed chiefly in fishes, from which the blood may 

 escape in such large quantity from the gills as to color the sea water. In other 

 instances, haemorrhages into the skin occur, and I have noticed during life, in the 

 dog-fish poisoned by Crotalus venom, the occurrence of intracranial haemorrhage. 

 Only one species of fish the puffer was wholly insusceptible to the locally irritat- 

 ing principles of venom ; it succumbed, however, to the general toxic effects of all 

 the venoms. 



It would appear as if the chief toxic effects of Crotalus and moccasin venoms are 

 the outcome of their local action, and yet the general toxic constituents which they 

 contain cannot be without marked action in some cases. These venoms may, there- 

 fore, 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 a far less degree of 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 



