SNAKE VENOMS, THEIR PHYSIOLOGICAL ACTION. 221 



work with dried and weighed quantities of venom. The poison may- 

 be collected in one of two ways : (1) the snake is canght by means 

 of a guillotine arrangement or a strong pair of forceps behind the neck. 

 If these are not available, a trained snake-man will serve the purpose 

 equally well. The animal, caught in either of these ways, is then 

 securely held with one hand behind the head. The lower jaw ig then 

 forcibly opened by catching the skin covering it. The fangs become 

 erected and the duct continuous. In the case, however, of the Daboia 

 which has exceptionally long fangs, it is well to pass a piece of string 

 behind them and pull them forward with this. With the finger and 

 thumb of the other hand firm and steady pressure from behind forwards 

 is made over the glands situate behind the orbits. The poison escaping 

 from the fangs is caught in a watch-glass held by an assistant in a 

 pair of long forceps. The process is, you will understand, a process of 

 squeezing, not, as we sometin:^s call it, one of " milking ; " (2) the 

 snake, held securely behind the head, is allowed to bite through a piece 

 of rubber stretched over a watch-glass or other suitable receptacle. 

 The liquid poison is then q-uickly anti thoroughly dried over lime or 

 sulphuric acid. I have carefully estimated the average amount of 

 Venom which can be got in this way. I find that a medium-sized 

 Cobra, that is, one from 500 to 1,000 grammes weight ( | to 1^ lbs.), 

 will yield about 200 milligrammes of dried poison ; the larger-sized 

 Cobras will give as much as 240 to 250 milligrammes or even more, * 

 The amount of water contained in fresh liquid cobra poison varies 

 from 60 to 75 per cent., so that fresh cobra venom is a 2j5 to 40 per 

 cent, solution of the dried material. 



Let us say that a Cobra gives 200 milligrammes of dried venom. 

 This is sufficient to kill 5,000 ordinary rats. It is, of course, without 

 actual experiment, impossible to say how much Cobra venom it takes 

 to kill a man ; but, calculating this amount on the basis that man is as 

 susceptible, weight for weight, as a rat, and from my experiments 

 on mice, rats, rabbits, monkeys, and horses, I have no reason to 

 think that he is less susceptible, then 200 milligrammes of poison—s-the 

 amount which can easily be got from a Cobra — would be suflScient to 

 kill eight ordinary- sized men, that is to say, that a medium-sized Cobra 

 can inject eight times the quantity, which would be sufficient to kill a 

 man. A large Cobra would have ten times the necessary amount. 

 * 1 3iilligraiai»9='015 grain, or aiout ^ part of a grain. 



