364 



OPHIDIA. 



moving forwards alternately), as a result of wliich the mouth 

 and pharynx of the snake are gradually drawn over the animal, 

 the surface of which is at the same time made slippery by the 

 secretion of the buccal glands. During this process the larynx 

 is projected forwards between the rami of the jaws, so that respir- 

 ation can be maintained. After the completion of the laborious 

 process of swallowing, the animal appears to be entirely pros- 

 trated and passes a long period in inactivity, during which the 

 slow digestion takes place. 



Some snakes kill their prey by crushing, e.g. Python ; some 

 by poison ; and others, the majority, swallow their prey directly. 

 The poisonous snakes belong to different families and cannot 

 easily be distinguished by any external mark from tlie non- 

 poisonous. The poison is secreted by some of the upper labial 

 glands, and is introduced into the subcutaneous tissue of the 

 victim by a groove (in the Viperidae converted into a canal) on 

 the anterior side of some of the maxillary teeth 



Tlie actual poison of the venom appears to consist of albuminous 

 substances in solution, and is different, judging by its action, in different 

 snakes.* The best treatment is to inject the serum of animals which 

 have been rende-red partially immune by repeated doses of the venom. 

 Failing this, the best plan is to apply a ligature above the wound, twisting 

 the string with a stick, and then to make a free incision of the wound. 



Then bandage the limb downwards towards the wound, repeating this 

 several times. Direct application into the widened wound of bleaching 

 powder (calcium hypochlorite) or of a 1 per cent, sokition of Condy's 

 fluid is good. Amputation is of course the best remedy, if a very deadly 

 snake has bitten the part." Alcohol and injection of ammonia are use- 

 less, and sucking the wound is dangerous. Many mammals are said to 

 be immune to snake venom, e.g. the mongoose, the hedgehog and the pig. 



Most of the species distinguished by size or beauty of colour 

 belong to the warmer zones, only the smaller forms extend 

 into northern temperate climates. Many snakes are fond of 

 the water and are truly amphibious. Others live for the most 

 part on trees or shrubs, or on sandy ground ; others exclusively 

 in the sea. In temperate climates they fall into a kind of winter 

 sleep ; in hot countries they may undergo a summer sleep in the 

 dry season. 



About 400 genera and 1,800 species are known. Very few 

 fossil forms are known. It is claimed that they make their first 



* See Martin in AUbutt's System of Medicine, 2, London, 1896. 



