424 THE SNAKES OF SOUTH AFRICA. 



and sub-human life is likel}^ to ensue. The ravages of plagues, 

 which in the past have prematurely swept off millions of human 

 beings and animals, have been checked and ultimately conquered 

 by the efforts of scientists who, however, were obliged, as a 

 general rule, to experiment on animals to discover the life 

 history of the microbes, nature of the disease, and the physio- 

 logical action of various substances when an antidote was being 

 sought. 



Polyvalent and Special Anti-venomous Serum. 



Anti-venomous serum is made polyvalent as a general rule, 

 viz. capable of neutralizing the venoms of the Cobra and Viper 

 families of snakes. This necessitates the injection of horses with 

 the venoms of both Cobras and Vipers. The venom of the 

 Cobra is an intensely virulent poison known as neurotoxin. On 

 the contrary, the venom of the Adders acts on the blood and 

 blood vessels, causing bleeding under the skin, mto the muscles, 

 vital organs, and from the mucous membranes. It is, in con- 

 sequence, technically called hcemorrhagin. 



Although neurotoxin is predominant in Cobra venoms, and 

 haemorrhagin in Adder venoms, yet all snake poisons contain 

 what is known as a fibrin ferment, which causes clotting of the 

 blood under certain circumstances. This is present in Cobra 

 venoms, but is much stronger in the venoms of Adders. When 

 snake venom is injected direct into a vein, this fibrin ferment 

 causes the blood to clot, and in these instances even anti- 

 venomous serum is powerless, and death rapidly ensues — some- 

 times within five minutes of the infliction of the bite. Fortu- 

 nately, however, a vein is seldom punctured by the fang of a 

 snake when it strikes. Special serums are also prepared, one 

 for use in the treatment of bites by all species of Cobras and the 

 deadly Mamha, and another for the treatment of the bites of all 

 species of Adders. It is possible to raise the immunity of a 

 horse to a very high degree by injecting with only one form or 

 kind of snake poison, either a neurotoxin or a haemorrhagin 

 separately. Hence the desirability of having these special 

 serums available. If the symptoms of Cobra and Adder venom 

 poisoning are carefully studied, it is easy, as a general rule, to 

 diagnose whether the bite is from one of the Cobra sub-family 

 of snakes, or one of the Adder group. 



