354 SXAKE- VENOM. 



Altlioug'li one drop of cobra venom and four drops of piilf 

 adder venom are fatal doses for human beings, it does not 

 follow that this dosag'e would always prove fatal, for, besides 

 the varying degrees of vital resistance in the human subject, 

 the venom itself* varies in its poisonous properties — one drop 

 at times being as potent as two, three and four drops at other 

 times. 



Recently I collected some venom from nine ringhals cobras 

 (SepeJon liaemachates). These snakes had been in captivity 

 for three months, refusing- all food, and had not been artifi- 

 cially fed. The venom could hardly be termed a fluid, for it 

 became sticky immediately after extraction, and in a very short 

 time was dry and hard, furnishing a deep yellow extract of 

 unusual weight for the quantity of venom obtained. The toxic 

 properties of this venom were three times that of fresh good- 

 conditioned snakes of the same species. 



In the second edition of my " Snakes of South Africa " it 

 is mentioned that some ringhals cobras which were bitten by 

 boomslangs {Dispholidus ti/pus) did not manifest any sign of 

 poisoning. Not being satisfied that the reptiles had been 

 sufficiently well bitten to cause death, I waited until further 

 boomslangs could be obtained. When these were forthcoming 

 I made one of them inflict tliree full bites into the muscles of 

 the back of an adult rinfflials cobra {Sepedoii liaemachates). 

 Half an hour after the bites, blood oozed from the punctures, 

 and to a small extent from the mucous surfaces of the mouth. 

 In two hours the victim died, and a post-mortem examination 

 revealed several large patches of extravasated blood under the 

 skin, chiefly in the Aacinity of the punctures. Haemorrhage 

 had occurred into the organs, with the exception of the dig*es- 

 tive tract, and about a teaspoonful of blood and lymph was 

 found free in the abdominal cavity. 



The blood was in a fluid condition. Some of it was 

 collected and put aside, but it failed to coagulate. A rat 

 inoculated with the blood died in thirteen hours. Another adult 

 ringhals cobra was i)laced in a cage with a very pugnacious 

 boomslang, which immediately attacked it and inflicted several 

 bites on its back. The boomslang was then removed, and, after 

 about fifteen minutes, blood slowly oozed from the punctures 

 in the ringhals and from the mucous membranes of the mouth. 

 In two and a half hours the ringhals cobra died. Dissection 

 revealed the same conditions of haemorrhage as in the former 

 instance, with the exception that it was more extensive owing 

 probably to a larger dosage of venom having been injected. 

 These experiments demonstrate that the venom of the boom- 

 slang is fatal to the ringhals cobra, and that the latter reacts 

 to the venom similarly to warm-blooded animals. 



Further experiments showed the ringhals cobra to be 

 susceptible to the venom of the Tajje cobra (Naia fiara), so 

 much so that one full bite is lethal. 



