SNAKE VENOMS 173 



1 gm. cobra or aspis kills 4000 kgm. of rabbit. 



1 gm. hoplocephalus kills 3450 " " " 



1 gm. fer de lance or pseudechis kills .... 800 " " " 



1 gm. Crotalus horridus kills 600 " " ' " 



1 gm. Pelias berus kills 250 " " " 



The danger of the bite depends not only upon the difference 

 in the strength of the venom of different varieties of serpents, but 

 also upon the size of the snake, the time of year and condition of 

 hunger or plenty, and particularly whether the entire discharge 

 is injected successfully or not. Probably in the majority of 

 strikes, by no means all the fluid ejected by both fangs is injected 

 beneath the skin of the victim. A large diamond rattler may 

 eject as much as a teaspoonful of venom at one discharge and 

 such a dose would usually be fatal. Repeated ejections decrease 

 the strength of the venom rapidly, until it may have almost no 

 toxicity. In general, venom is most active in warm weather 

 and immediately after the snake has fed ; in winter its toxicity 

 is slight. 



The mortality in America from snake-bites is very hard to 

 ascertain, various authors giving figures at wide variance. Weir 

 Mitchell gives one series with a mortality of 25 per cent., and 

 another series in which it was 12 per cent. ; Ellzey gives 15 per 

 cent. These figures are probably high, since fatal cases are 

 much more likely to find their way into the literature than 

 those in which the results are trifling. Some authors go so far 

 as to say that there are no authentic cases of death from copper- 

 heads or moccasins, but this is undoubtedly incorrect. 1 How- 

 ever, the reputed danger from these snakes is undoubtedly much 

 exaggerated, many deaths from snake-bites of all kinds being 

 due to the treatment rather than to the bite. The poisonous 

 snakes of Australia, although numerous, are not very virulent, 

 and the mortality is given as about 7 per cent. A full charge 

 of venom from the cobra and many other Indian snakes is in- 

 evitably fatal (Fayrer). The crotaline snakes of the tropics are 

 more venomous than those of the north, Lacheris lanceolatus of 

 Central America and Mexico being nearly as dangerous as the 

 cobra. 



When venom is taken into the stomach in the intervals of 

 digestion, enough may be absorbed to produce death, especially 

 in the case of those venoms which contain a large proportion of 

 the albumose, which is dialyzable ; but during active digestion 

 the venom undergoes alteration and is rendered harmless. It 

 has been found experimentally in animals that cobra venom 



1 Concerning copperhead poisoning see Yarrow, Amer. Jour. Med. Sci., 



1884 (87), 422. 



