SNAKE -VENOMS. 483 



tion to the " Lancet," showed that Calmette's serum, 

 obtained from horses, gradually immunised with cobra 

 venom, furnished a serum of fairly high neutralising 

 value, viz., that 1 c.c. of the fresh serum was able to 

 neutralise "73 mgrm. of dried cobra venom, and, further, 

 it was shown that 'this anti-venomous serum undergoes 

 progressive and rapid deterioration when stored in hot 

 climates. Some further work on daboia poison showed 

 also that Calmette's serum was absolutely useless 

 in cases of viper poisoning, 4 c.c. not neutralising 

 even such a small quantity as '125 mgrm. of dried 

 viper poison. 



Of considerable interest is the question of the natural 

 immunity of venomous and other snakes to these poisons. 

 Fraser explains this immunity as due to snakes swallowing 

 their own poison. Kanthack, however, was unable to 

 obtain antitoxic effects from the serum obtained from fresh 

 cobras. Cunningham has since confirmed this, and added 

 that " the natural immunity of cobras is perfectly distinct 

 " in its nature from the artificial immunity established as 

 " the result of continued treatment with snake venom, and 

 " is unconnected with any material of the nature of an 

 " antitoxin." 



Although the serum of the cobra has no neutralising 

 power against daboia venom, yet the cobra possesses great 

 immunity against the bite of this viper. Many innocent 

 snakes are also resistant to cobra bite. 



That inoculation of a cobra with its own venom does not 

 lead to neutralising bodies being produced in its blood has 

 been shown by Cunningham, and this investigator is 

 inclined to believe that the degree of susceptibility runs 

 parallel with that of respiratory requirement, Batrachia, 

 which have a low respiratory requirement, being relative! v 

 insusceptible, 



