244 TROPICAL MEDICINE AND HYGIENE 



3. TREATMENT OF SNAKE-BITE. 



(i) Theory of Treatment. With regard to this subject 

 a few words on immunity, natural and acquired, are 

 necessary as a preface. 



It has been settled by experiment not only that a 

 venomous snake is normally tolerant of the poison of 

 its own species, and in some cases at least of that of 

 other species, but also that some of the harmless Colu- 

 brines show resistance or even complete immunity to 

 snake-venom. Thus two South American Opisthoglyphes, 

 namely, Erythrolamprus cesculapii and Rhachidelns brazili, 

 are said to be completely indifferent to the venom of the 

 various poisonous snakes that form their habitual food ; 

 and an American Aglyphe, Coronella getula, which over- 

 powers and devours rattlesnakes, is said to be immune to 

 the venom of its prey. Furthermore, and quite apart 

 from myth, there are mammals among them, in par- 

 ticular, the mongoose, the hedgehog, and the pig that 

 are known to possess some tolerance of snake-venom. 



Acquired immunity to snake-venom is also known. 

 Not only in the mystic circle of snake-charmers, but 

 outside it, there have been men who have accustomed 

 themselves to the poison of a particular species of snake 

 by the simple process of inoculation with a very small 

 dose followed by a series of doses of gradually increasing 

 strength. Sewall demonstrated, in 1887, that pigeons 

 could be immunized in this way to the venom of the 

 rattlesnake; and between 1892 and 1894 Calmette was 

 successful in working horses up to such a degree of 

 tolerance of cobra-venom that at last they were able to 

 stand, at a single injection, a dose of venom estimated 

 by him to be strong enough to kill eighty uninured 

 horses. The serum of horses so immunized to cobra- 

 venom was proved by Calmette to have antitoxic powers. 

 Calmette believed at first that it was antitoxic to all 

 venoms, but it has since been shown, particularly by the 

 experiments of Martin, Lamb, and Rogers, that this is 



