482 SNAKES OF CEYLON. 



Fayrer* (Expt. 3 of Series 16) caused a cobra to bite a dog 

 in a fold of skin in the groin. The wound was entirely excised 

 " at once," but death took place in 6 minutes ! In another 

 experiment (No. 13 of Series 15), the same authority repeated 

 the same performance, the part being " immediately " excised 

 (within 2 seconds). The animal died 2 hours and 35 minutes 

 later. It appears probable that the initial absorption 

 of the poison is far more speedy in the first few seconds 

 (or minutes) than subsequently (?). Acton and Knowles 

 have repeated these experiments, and find that if amputation 

 is not accomplished within ten minutes of a lethal 

 injection, the amount already absorbed will cause a fatal 

 issue. 



(g) Lethal Dose for Man : It is a well-established fact that 

 cobra venom may be swallowed in large quantities without 

 producing any baneful results. Elliot gave a dog 10 drops — 

 a dose sufficient to kill 10 dogs, if injected into the tissues — 

 without producing any ill -effect. On another occasion he 

 gave 20 drops to a goat with the same result. Fraser, by 

 graduated doses internally, succeeded in giving a cat 1,000 

 times the lethal dose by injection beneath the skin. Calmette 

 repeated the experiment, giving 1,000 times the lethal sub- 

 cutaneous dose to a cat internally, without producing symptoms 

 of poisoning. It is the access of the venom into the blood 

 stream that constitutes its extreme danger to all animals. 

 The lethal dose of the poison so introduced has been accurately 

 ascertained for many animals by experiment, but in man 

 must remain to some extent conjectural. Various estimates 

 have been made, based on experiments on the lower animalss. 

 Fraser's estimate is 31 mgms., whilst Calmette made it about 

 10 mgms. Lamb, however, finding that -25 mgms. is approxi- 

 mately the minimal lethal dose per kilogram weight in monkeys 

 and postulating an equal degree of susceptibility in man, 

 concludes that the dose for a man weighing 10 stone would be 

 about 15 to 17*5 mgms. (or -0015 to -0017 grammes). If we 



Thaiuitophidia of India (1874). 



