368 THE SNAKES OF SOUTH AFRICA. 



stages this numbness extends all over the body and causes syncope 

 and fainting fits. The victim slowly but steadily sinks into a 

 profound state of drowsiness and an irresistible desire to sleep 

 steals over him. Pupils of eyes contract. The breathing 

 becomes increasingly difficult. The legs grow numb and limp. 

 The coma and difficulty of breathing become more profound, the 

 pulse steadily weakens. Sahva runs from the mouth ; the tongue 

 and larynx are paralysed with inability to speak. 



Vomiting, involuntary emissions of urine and foecal matter 

 happen, and the breathing becomes more difficult. The heart's 

 action is quickened. The pupil of the eye remains contracted and 

 reacts to light up to the last moment. At length breathing ceases, 

 and the heart continues to beat after respiration has ceased. This 

 all takes place in from one to seven hours. Should the patient 

 survive, he returns rapidly to complete health. 



After death the only outward sign of Cobra poisoning is 

 discolouration around the site of the fang punctures. There is 

 no swelling or extensive subcutaneous haemorrhage, as is the 

 case with Adder venom poisoning. 



ViPERiNE Venom. 



The venom of Vipsrine snakes, of which our Puff Adder, 

 Horned Adder, and Berg Adder are examples, differs considerably 

 in its physiological action from that of the Cobra (Colubrine) 

 family. The neurotoxins or nerve poisons in it are not nearly 

 so potent in their action as is the case with the nerve poisons in 

 Cobra venom. But, whereas Cobra venom causes increased 

 action of the heart and consequent increased blood pressure, 

 Viperine venom slows down the pulsation of the heart and 

 circulation of the blood. This narcotic power of the venom 

 extends to the general nervous system, bringing about a state of 

 nerve depression more or less severe according to the amount of 

 venom injected. 



Cobra venom acts powerfully upon the nerve centres con- 

 trolling the breathing functions, and tends to stop the action of 

 the lungs. Viperine venom, on the other hand, exerts no special 

 effect upon these nerve centres. The neurotoxin in Viper venom 

 acts on the vaso-motor centre causing a variation of blood 

 pressure. On the contrary, the neurotoxins of Cobra venoms 

 powerfully stimulate the heart. 



