SNAKE VENOM 



379 



The cobra, after having bitten, remains attached for a short time while the 

 daboia strikes with the greatest rapidity and immediately releases itself. 



Cobra and krait bites (colubrine snakes) produce more or less 

 similar symptoms such as paralysis of articulation with nausea and 

 vomiting and later paralysis of the respiratory apparatus. There is 

 only an insignificant reaction at the point of bite. 



The venom is mainly neurotoxic, causing death by paralysis of cardiac and re- 

 spiratory centers. Cobra venom is also very haemolytic. This hasmolysin is acti- 

 vated by the normal complement of the serum of the animal poisoned, the hsemolysin 

 as contained in the venom not being toxic when alone. Lecithin also has the 

 property of activating the haemolytic amboceptor of venom. 



In rattlesnake bites (viperine snakes) there is marked pain at the 

 site of the wound with much swelling and haemorrhagic infiltration. 

 The swelling and petechial mottling spread up the limb from the point 

 of entrance of the venom. Cold sweats, nausea, weak heart, and syn- 

 cope are common 



Rattlesnake venom is active chiefly on account of its haemorrhagin or rather 

 endotheliolysin, which destroys the endothelial lining of blood-vessels. 



Venoms may also contain proteolytic ferments Which may account for the softening 

 of muscles in snake-bite cases. The toxic effect of the venom takes place without an 

 appreciable incubation period, hence different from true toxins. 



The most venomous snakes seem to be the sea-snakes (Enhydrina) . This venom 

 is almost entirely neurotoxic. 



The tiger snake of Australia is almost equally venomous and the krait (B. cceruleus) 

 next. The rattlesnake is about one-fifth as venomous as the krait. 



Certain venoms greatly increase the coagulability of the blood so that intravas- 

 cular thromboses may occur. It is chiefly with the venoms of Daboia and Bun- 

 garus that such thromboses are likely to occur and this accounts for the almost 

 instantaneous death which at times results from bites of such snakes. 



The nonspecific treatment of snake-bite poisoning is i. by applying a tight ligature 

 above the site of the bite. The ligature, which should preferably be a rubber band, 

 is to be applied about a single bone extremity, not about one with two supporting 

 bones. 2. The making of deep incisions about the fang punctures and thorough 

 irrigation with a strong solution of potassium permanganate. Rogers has recom- 

 mended that the punctures be enlarged with a lancet and the resulting wound packed 

 with crystals of permanganate. 



Recently Bannerman has shown that a dog bitten by a cobra cannot be saved 

 by free incision and the rubbing in of permanganate crystals. It may however be 

 saved by the immediate injection of 10 c.c. of a 5% solution of permanganate, but 

 not if two minutes has elapsed. Bites from the daboia are fatal, however the per- 

 manganate be applied. 



He therefore does not consider the permanganate treatment of any practical 

 value. Rogers thinks that Bannerman's experiments with dogs do not give a true 



