﻿182 STRONG. 



Experiments in the immunization of monkeys with the strain "Maassen 

 Alt." — Four monkeys in Series 17 (p. 212) were vaccinated, three with 

 2 agar cultures and one with 1 culture of the strain "Maassen Alt." 

 Twenty days afterwards their immunity was tested by the inoculation of 

 \ oese of the strain "Pest Virulent," when all which had been vaccinated 

 with the two cultures proved to be thoroughly immune, while the animal 

 which had received only one culture died of pest. Every one of ten 

 control (nonvaccinated) monkeys inocidated in the same manner died 

 of the infection. 



Twelve monkeys in Series 21 (p. 213) were vaccinated, each either 

 with 1 or 2 cultures of this same strain, "Maassen Alt." On testing their 

 immunity two weeks later by the inoculation of \ oese of the strain "Pest 

 Virulent" it was found that of the eight vaccinated with 2 cultures, 

 two died after a somewhat prolonged infection and of the four vaccinated 

 with 1 culture, two also died, one after a prolonged illness. Therefore, 

 the mortality in this series was 33.3 per cent, 66.6 per cent of the 

 monkeys having been immunized. Each of twelve control animals 

 inoculated at the same time succumbed to pest infection. 



Eighteen monkeys in Series 24 (p. 215) were inoculated with agar 

 cultures of this organism ("Maassen Alt"), one with \ a culture, and the 

 remainder with 1 or 2 cultures. Four of these animals died after the 

 vaccination. It seems clear that the animal numbered 1552 died from 

 the effects of the vaccination and in the remaining three monkeys, death 

 probably occurred both from the same cause and from that of infection 

 with pyogenic cocci. Two weeks later on testing the immunity of the 

 nine which were inoculated with 2 agar cultures and which survived 

 the vaccination, all but one (number 1545) were found to resist the 

 infection. This one died of pest. On testing the immunity of the 

 four animals which had been inoculated with 1 culture and of the one 

 which had been given \ culture, all were found to be immune. Hence 

 the entire mortality in this series was 28 per cent. However, as a 

 number of the control animals inoculated at this time and in the same 

 manner did not die, the remaining 72 per cent of- the animals of this 

 series can not be. regarded as being of necessity highly immunized. 



Fifteen other monies in Series 52 (p. 217) were inoculated subcuta- 

 neously each with 1 agar culture of the strain "Maassen Alt." One of the 

 animals died thirteen days after vaccination. The cause of death could 

 not be discovered at autopsy. One month after the vaccination, on testing 

 the immunity of the remaining fourteen by the subcutaneous inoculation 

 of f oese of the strain "Pest Virulent," seven died and seven survived the 

 inoculation. 



In all, forty-nine monkeys were vaccinated with the strain "Maassen 

 Alt;" of these, four probably succumbed from the effects of the vaccina- 

 tion and one from an unknown cause. On testing the immunity of the 



