224 VENOMOUS SNAKES AND THE PHENOMENA OF THEIR VENOMS 



unchanged to cause the typical poisoning if large doses are given. From their 

 experiments they conclude that venoms contain two distinct principles, one 

 of inflammatory action, comparable to certain diastase, for which they sug- 

 gest the name echidnase; the other of general action, actively impressing 

 the nervous system and described as echidnotoxin. They found that after 

 guinea-pigs were injected with heated venom they could resist a minimal 

 fatal dose of venom. This protection they ascribe to the echidnase. 



Phisalix and Bertrand, and simultaneously Calmette, transferred the stage 

 of active immunity to the more important stage of passive immunity — or the 

 era of antivenins, and this will be treated in full under "passive immunity." 



It may be stated in this connection that for some time neither Kanthack ^ 

 nor Calmette ^ could perceive any increase in resistance to venom after treat- 

 ing the animals with non-lethal doses. The first-named investigator employed 

 both the venom and blood of cobra for the injections, but without favorable 

 protective result. 



Fraser ^ made some very interesting observations on the production of 

 immunity by administering the venom through the alimentary tract. He 

 immunized a cat by gradual administration of venom per os, until it could 

 take I gram at a dose, this being equivalent to 80 minimal lethal doses calcu- 

 lated from subcutaneous injection. Eight days after the large dose men- 

 tioned it was injected with 1.5 times the subcutaneous dose without harm. 

 The cat was pregnant, and on the fifty-fourth day of the administration gave 

 birth to kittens, which continued to suck the immunized mother. On the 

 fifty-seventh day after birth one of the kittens was given two minimal lethal 

 doses of the venom and showed scarcely any symptoms. Another, on the 

 sixty-ninth day after birth, received three minimal lethal doses, but died. 



According to Fraser httle venom is absorbed from the stomach. To a series 

 of white rats he administered by the mouth, 10, 20, 40, 200, 300, 600, and 

 1,000 times the subcutaneous fatal dose, but all remained well except for 

 slight drowsiness. The rat which received the 1,000 fatal doses was 8 days 

 afterward given two fatal doses subcutaneously, was sick in consequence, 

 but recovered. 



Kanthack* was able to confirm Eraser's statement that animals can be 

 immunized by alimentary administration of venom. 



Phisahx and Bertrand ^ state that the injection of heated (68° C.) serums of 

 viper and adder into the peritoneal cavity of guinea-pigs confers after 24 

 hours the power to resist the effect of one fatal dose of venom. 0.25 c.c. of 

 the heated serum was sufficient for that purpose; the blood of adders had a 

 similar, but less intense, protective power. 



» Kanthack. The nature of cobra poison. Jour, of Physiol., 1892, XIII, 272. 



2 Calmette. Le venin de Naja tripudians. Ann. de I'lnst. Pasteur, 1892, VI, 160. 



8 Fraser. The treatment of snake poisoning with antivenin derived from animals protected against 



serpent's venom. Brit. Med. Jour., 1895, II, 416. 

 * Kanthack. Report on snake venom in its prophylactic relation with poisons of the same and other 



sorts. Rep. Med. Off. Loc. Gov. Bd., 1895-6, Lond., 1897, 235-266. 

 ^ Phisahx and Bertrand. Sur I'emploi du sang de vipere et de couleuvre comme substance antiveni- 



meuse. Compt. rend, de 1. Soc. d. Biol., 1895, 10 serie, II, 751. 



