POISOXOUS SXAKES 



31 



where people go with hare feet and legs through the jungle, the time has 

 heen when mortality from snake bite reached twenty thousand annually. 

 This was before the discovery of antivenin, a serum prepared in the same 

 way as germ disease antitoxins and now for sale in India, as in other coun- 

 tries where branches of the Pasteur Institute have been established. As 

 early as 1887 experiments proved that repeated inoculations of snake venom 

 put an animal into a condition resistant to the venom, hut not until 1894 

 was a serum dispensed for practical use. 



In North America accident from snake bite has always l)een a rare 

 happening, the dangerous species l)eing few — namely, two moccasins, the 

 copperhead and the cottonmouth (Anci.sf radon), two coral snakes (Elaps), 

 small brilliantly colored allies of the cobras, and thirteen rattlesnakes 

 {Stfitrurus and Crotalus). With the exception of the coral snakes, these 

 are all "pit vipers" and can be recognized when .seen near at hand by a 

 pecidiar deep depression, of questioned function, between the eye and the 

 nostril and also by a vertical pupil. But for snakes in general the venomous 

 species is marked l)y no peculiar structure except the poison apparatus 

 itself, and many non-poisonous snakes even possess the poison glands in a 

 primitive stage of development, lacking only the poison-conducting fang. 

 Therefore in North America where out of about one hundred and ten 

 species only seventeen are dangerous to man, and of these not often more 

 than two occur in a given district, the problem of safety even for extended 

 expeditions into the wilderness demands merely a knowledge of the appear- 

 ance of the few given forms. 



PorlitJii of a nrw snako group thai gives acquaintance witli tlic deadly water nioccas-in 

 orthe .Soutli [tlie .snake in tlie foregroinid ; wax cast by James C. Bell, color work by Frederick 

 H. Sloll] 



