2994 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 1 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 little 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 Fraser’s statement that animals can be 
immunized by alimentary administration of venom. 
Phisalix 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. 


1Kanthack. The nature of cobra poison. Jour. of Physiol., 1892, XIII, 272. 
2Calmette. Le venin de Naja tripudians. Ann. de l'Inst. Pasteur, 1892, VI, 160. 
Fraser. The treatment of snake poisoning with antivenin derived from animals protected against 
serpent’s venom. Brit. Med. Jour., 1895, II, 416. 
4Kanthack. 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. 
5 Phisalix and Bertrand. Sur l’emploi du sang de vipére et de couleuvre comme substance antiveni- 
meuse. Compt. rend. de 1. Soc. d. Biol., 1895, 10 série, II, 751. 
