SPECIFICITY AND THERAPEUTIC VALUES OF ANTIVENINS 235 



Stephens * then brought out the very important fact that the haemolytic 

 principles of various kinds of venoms are not identical as far as their affinity 

 to Calmette's antivenin is concerned. He showed that, while the haemolytic 

 toxin of cobra venom is easily neutrahzed by this antivenin, those of daboia 

 or crotalus venoms remain almost unneutralized by the same. He concludes : 



(i) That antitoxic sera can act upon toxins other than, but allied to, those 

 used in the preparation of the serum. 



(2) That the haemolytic constituents of snake toxins, and hence snake 

 toxins as a class, are not identical. 



(3) That against a minimal lethal dose of daboia venom 0.5 c.c. of Cal- 

 mette's antivenin has very little action. 



(4) That the antihaemolytic properties of antivenomous sera must be 

 increased, in order to afford any efficient protective serum, e.g., against 

 pseudechis toxin or daboia toxin. 



Myers ^ found that cobra venom contained two principles, which he terms 

 cobralysin and cobranervin. The cobralysin, which is the haemolytic sub- 

 stance, is destroyed by heat, the cobranervin remaining unaltered. Cobralysin 

 can be neutralized by antivenin, the cobranervin remaining free. It is only 

 in minimal fatal dose that the neutrahzation of both goes together. With 

 multiples of the minimal fatal dose, a non-ha^molytic mixture of venom and 

 antivenin may rapidly kill a guinea-pig. 



The susceptibihty of the erythrocytes to the action of the cobralysin in vitro 

 bears no relationship to the susceptibihty of the animal to subcutaneous 

 toxication by the venom. In the lethal properties of the venom the cobra- 

 lysin plays an insignificant part. Toxoids rapidly form in dilute solutions of 

 venom, these toxoids seeming to be specific. 



McFarland immunized horses to unmodified crotalus venom mixed with 

 several other kinds of venoms and obtained an antivenin which was equally 

 effective against the venoms of Crotalus adamanteus, Ancistrodon contortrix, 

 Naja tripudians, and Cerastes. It was able to counteract only the neurotoxins, 

 but not local irritative principles. This experiment neither negatives nor 

 proves the question of the specificity of antivenins, as it was prepared with 

 mixed venoms. 



On the other hand, Flexner and Noguchi ^ produced an antivenin for cro- 

 talus venom by injecting venom modified by hydrochloric acid or trichloride 

 of iodine and found that the antivenin had a neutralizing action upon the 

 haemorrhagins; also that Calmette's antivenin has only a feeble protective 

 action against crotalus venom, as it has no anti-haemorrhagic power. 



In 1904 Jacoby made a series of experiments with the haemolysin-free 

 cobra venom in regard to its relation to the native unmodified venom. The 

 material which he employed was the aqueous solution of cobra venom, from 



1 Stephens. On the hjemolytic action of snake-toxin and snake sera. Jour, of Path, and Bact.> 



1899-1900, VI, 273. 

 * Myers. On the interaction of toxin and antitoxin; illustrated by the reaction between cobralysin 



and its antitoxin. Jour, of Path, and Bact., 1899-1900, 415. 

 <* Flexner and Noguchi. Production and properties of anti-crotalus venin. Jour, of Med. Research, 



1904, n. s., VI, 363. 



