NATURAL IMMUNITY 269 



crotalus serum. Unlike the venom, the crotalus serum is highly hemolytic 

 upon the mongoose corpuscles. 



Lewin 1 and Phisalix and Bertrand 2 made numerous experiments on the 

 immunity of the hedgehog against the venom of Vipera berus. It is known 

 that the hedgehog chases the viper and eats it very eagerly. The spinous 

 coat of the animal protects it from being bitten by the snake and the 

 animal is very skilful in catching the reptile at vulnerable parts of the body. 

 Should the snake succeed in biting the hedgehog, the latter seldom dies. 

 The inoculation of about 40 minimal lethal doses for guinea-pig of this venom 

 into the hedgehog is required to kill. Whether or not the resistance of this 

 animal is due to the presence of an antitoxic substance in the blood has been 

 studied by Phisalix and Bertrand, who state that the serum of this animal 

 heated to 58 C. in order to deprive it of its inherent toxicity for the guinea- 

 pig can, when mixed with 2 minimal lethal doses of the viper poison in quan- 

 tities of 8 c.c. of the serum, protect the guinea-pig from the fatal effects of 

 venom. 



Jn regard to the natural immunity of hogs, which is popularly credited in 

 the Mississippi Valley, it is still unconfirmed experimentally. Calmette 3 

 found the pig to resist more cobra venom than dogs (speaking proportionally) , 

 but its serum contained no antivenomous properties. Along the valleys of 

 the lower Mississippi it is said that the hog swallows young crotalus with 

 evident liking. 



Concerning the grallics of Colombia, the culebrero and guacabo, nothing 

 definite is known, except that these birds hunt young snakes for their prey. 

 Probably they are relatively immune to the bite of poisonous snakes, partly 

 because they understand how to kill the snake, and partly, perhaps, because 

 they are less sensitive to the effect of the venom itself. 



1 Lewin. Beitr. z. Lehre von der natiirl, Immunitat. Deutsch. med. Woch., 1898, XXIV, 629. 



2 Phisalix and Bertrand. Recherches sur l'immunitS du herisson contre le venin de vipere. C. R. 



Soc. Biol., 1895, 10 ser. II, 639. Ibid. Bull, de Museum d'Histoire natur., 1895, 1, 294; op. 

 at., II, 100. 



3 Calmette. Les venins, 1907, Paris. 



