538 SNAKES OF CEYLON. 



(c) Physical Characters : Stevenson says when dried the 

 venom assumes the character of amber -coloured scales. 



(d) Yield : As the poison in its hquid form varies much in 

 its degree of concentration, it is always measured by the 

 weight of the desiccated residue. This is found to vary 

 considerably, the amount depending on the vigour of the 

 snake. A freshly caught specimen yields much more than 

 one long in the vivarium. Acton and Kjiowles found the 

 average yield for 57 snakes, varying in length from 9 to 18J 

 inches, was IS'Smgms. The maximum jaeld was 72' 2 mgms. 

 from a specimen 18| inches long. 



Stevenson expressed 3 or 4 drops from the glands of one 

 snake in vigorous health. 



(e) Amount injected at one Bite : Acton and Knowles 

 estimate that about 12 '3 mgms. are injected at one bite, or 

 more than twice the lethal dose for an adult. 



(/) Toxicity : Compared with cobra poison echis venom is 

 nearly five times as toxic according to Acton and Knowles. 

 It is sixteen times more potent than the venom of Russell's 

 viper. 



(g) Rapidity of Absorption : Acton and Knowles's experi- 

 ments show that the absorption is so rapid that if a lethal 

 dose has been discharged into the wounds, sufficient will have 

 entered the blood stream in twenty minutes to cause death. 

 This means that local remedies, and even amputation 

 performed later than twenty minutes, will not avert death if 

 a lethal dose has entered the systemic circulation. 



(h) Lethal dose for Man : Acton and Knowles estimate that 

 the lethal dose in the human adult is about 5 mgms. This is 

 based on the assumption that man is as susceptible as the 

 monkeys upon which they experimented. 



(i) Uncertainty of the Effects : The yield varies considerably 

 even in adult echides, and this probably accounts for the fact 

 that a great many bitten subjects escape death. One specimen, 

 362 mm. (15^ inches) long, yielded 1"4 mgms., and another of 

 the same length 26 '8 mgms. One 470 mm. (18 J inches) long 

 yielded 40 "6 mgms., whilst another of the same length 

 furnished 72*5 (Acton and Knowles). In 36 experiments 

 conducted by Acton and Knowles, where rats were bitten by 



