SNAKE-VENOMS. 479 



Regarding daboia poison, we have no evidence as yet of 

 the amonnt causing a faital issue in man, but from 

 observations made in India, Captain Lamb and the writer 

 concluded that one part by weight per million of 

 circulating blood was quite sufficient to clot it solid in a 

 few minutes. 



The physiological action of the venoms of most of the 

 poisonous snakes has been much elucidated of late years. 

 Thus Weir Mitchell, in America, has carefully investi- 

 gated the nature and action of the venom of the rattle- 

 snake. The Australian black snake and tiger snake have 

 been similarly investigated by Martin, of Melbourne, 

 Wall, Cunningiiam, Kanthack, Stephens and Meyers have 

 all added work on the subject of these venoms. 



Less recent observers, such as Brunton and Fayrer, seem 

 to have regarded the physiological action of cobra venom 

 as identical with that of viper poison. All recent 

 investigators, however, have shown beyond doubt that the 

 toxic eifects of cobra venom are quite different from the 

 effects of the venom of true vipers. 



Calmette has also recently stated that snake venoms 

 differ from one another only in the degree of their toxicity, 

 and that they are all of the same nature. On examining 

 the literature of the subject, it would appear that although 

 the accounts of the symptoms produced coincide, yet there 

 is a divergence of opinion as to the cause of these. 



Most writers agree that the action of cobra venom is 

 chiefly on the central nervous system ; yet Cunningham 

 contends that it acts primarily as a blood poison, the action 

 on the nervous system being secondary. 



Eegarding the cause of death in viperine poisoning, 

 Martin, who worked with the black snake and tiger snake, 

 believes that all rapid deaths from bites of these snakes 

 are due to extensive clotting in the blood vessels. 



