﻿V. IMMUNIZATION OF ANIMALS. 



1. WITH KILLED PEST BACILLI. 



Yersin,, Calmette and Borrel :i5 in 1895 first called attention to the 

 fact that rabbits, inoculated STibeutaneously on three or four occasions 

 with gelatine cultures of the pest bacillus killed by heating for one hour 

 at 58° O, were rendered immune to subsequent subcutaneous inoculations 

 of virulent plague bacilli. Guinea pigs were much more difficult to 

 immunize, and they rarely succeeded in thoroughly protecting one of 

 these animals by such a method. 



Wyssokowitz and Zabolotny 3C mention that monkeys can be immunized against 

 pest by the inoculation of killed cultures of the organism, although they give no 

 details showing the percentage of animals that were protected by the use of 

 this method. 



The German Plague Commission 3T found that all the monkeys of the species 

 Maeacus radiatus which received subcutaneously one carefully killed, two-day 

 culture of the virulent pest organism were able later to resist almost without 

 reaction the subcutaneous injection of one full oese of the living culture. How- 

 ever, with this same amount they were not able to immunize gray monkeys of 

 the species Semnopithecus entellus against plague infection, and the Commission 

 did not have time to pursue the question further with this species of animal. 

 However, they demonstrated in a series of rat inoculations that a large per- 

 centage of the animals could be immunized with killed cultures of the pest 

 organism against subsequent subcutaneous infection, if the dose was sufficiently 

 large (2 killed agar cultures). One agar culture did not suffice to immunize 

 the animal. The rats often succumbed from the effect of the large dose of the 

 primary inoculation. 



Albrecht and Gohn 37 state that they were able to immunize guinea pigs by 

 repeated doses of killed agar cultures of the pest bacillus, although the immunity 

 obtained was not great. In their experiments with these animals, described in 

 their report, the guinea pigs all finally died of pest infection. 



Tavel, Krumbein and Glucksmann ** were able to obtain immunity in some 

 instances in the course of a small number of experiments with rats, by the 

 inoculation of large amounts of the killed cultures, but they were unable in 

 many experiments to immunize a single guinea pig even by using repeated 

 inoculations of the killed cultures. 



Beinarowitch 39 concluded that the injection of killed cultures of the pest 

 bacillus conferred an immunity upon rodents, but that this was very slight, unless 

 the inoculation was repeated several times. 



35 Ann. d. I'inst. Pasteur (1895), 9, 589. 

 30 Ibid ( 1897 ) , 1 1 , 667. 

 37 Log. cit. 



3S Zlsrhr. f. Hyg. u. Infectionskrankh., Leipz. (1902). 40, 239. 

 30 Arch. d. Sci. Biologiques (1903), 9, 343. 

 176 



