REPTILES 419 



DISEASES DUE TO VENOMS AND POISONS. 



INTRODUCTORY REMARKS. 



Venoms are useful : — 



(i) To keep off enemies by discharging the venom into the sur- 

 rounding medium, e.g., toads, salamanders. 



(2) To aid nourishment by the animal mixing the venom with its 

 own digestive juices, e.g., snakes. 



(3) To serve as a means of attack or defence by inoculating the 

 venom, e.g., snakes, scorpions, &c. 



Animals are venomous only when they are capable of inoculating 

 their venom. Among these, reptiles form the greater part. 



Humanity has held strange and contradictory ideas with regard to 

 reptiles all down the ages. For example : — 



In Genesis the serpent represented the Evil One. 



In Greece it symbolized wisdom and prudence. 



In Egypt it was the protector of crops and represented immortalit}-. 



In Rome its presence caused epidemics to cease. 



In India the living Xaja represents happiness and prosperity, the 

 dead reptile, terrible calamity. 



There is an average of 25,000 deaths per annum from snake-bite in 

 the Indian Peninsula alone. 



300,000 vipers have been killed in Haute-Saone, France, during 

 twenty-seven years (Calmette). 



It is interesting to note that the blood also of vipers, toads and 

 salamanders is toxic and that the eggs too carry the venom. 



REPTILES. 

 GENERAL FEATURES. 



A thick epidermis covering the skin is detached or moulted three 

 or four times yearly in all except a few species of snakes, and these 

 retain a few rings at the tip of the tail as in the rattlesnake, by means 

 of which it makes the noise so characteristic of it. This moult is pre- 

 ceded by several weeks of torpor during which the reptile does not eat. 

 The epidermis becomes dull, dry and wrinkled, later cracking at the 

 mouth after which the reptile awakes, shakes itself free from the 

 remainder and goes once more in search of food. 



Their coloration, governed generally by mimicry, is not of much 

 value for diagnostic purposes as it may be modified several times 

 during the life of the same reptile. 



