358 THE SNAKES OF SOUTH AFRICA. 



different more or less in their physiological action, but they are 

 in varying proportions, hence the reason of the differences in 

 the effects on the human body and the symptoms arising from 

 those effects. 



The nerve poison (neurotoxin) can be separated from the 

 blood poison (haemorrhagin) of snake venom, by adding lecithin 

 dissolved in chloroform, with a solution of venom, and shaking 

 vigorously. The blood-poison combines with the lecithin to 

 form an active lecithide which dissolves in the chloroform and 

 can be afterwards precipitated by ether. 



The neurotoxin or nerve-poisoning principle of the venom 

 remains in the liquid solution. The part which has been precipi- 

 tated, if injected into animals, destroys the red corpuscles of 

 their blood, inducing haemorrhage into the tissues. Its action is 

 very rapid, especially when a concentrated solution is used, being 

 then much more active than before separation from the neuro- 

 toxin. 



Weight for weight, the venoms of the different species of 

 snakes vary considerably. The venoms of the Mamba, the 

 Cobra, and Boomslang have as powerful poisoning effect as 

 three to five times the weight or bulk of Puff Adder, Berg 

 Adder, or Night Adder venom.* 



The poisonous effects of all venoms vary according to the 

 size and vital resistance of the victim. For" instance, a cat is of 

 about the same weight, or even less, than a large fowl or rabbit, 

 yet its power of resistance to the poisonous action of venom is 

 considerably greater. A Boomslang was forced to bite the 

 bared thigh of a domestic cat of adult size, and was permitted to 

 retain its grip for half a minute. The cat gradually developed 

 symptoms of poisoning and died in thirty hours. Large cock 

 fowls and rabbits bitten by the same snake died within fifteen 

 minutes. An interesting feature of these cases was the different 

 symptoms. The cat was strongly acted upon by the blood- 

 poisoning principle of the venom, for the wound oozed blood 

 all the time, and the mucous surfaces discharged blood ; and after 

 death, extravasated blood was found in various tissues. On 

 the contrary, no such symptoms were apparent in the fowls 

 and rabbits. The neurotoxin or nerve-poisoning principle in 



* no drops of Puff Adder venom after being dried over calcium chloride 

 yielded 24^ grains of dry extract. 



