﻿STUDIES IN PLAGUE IMMUNITY. 165 



it seems •unquestionable that large and repeated doses of Haffkine's prophy- 

 lactic frequently protect individuals against plague infection, although 

 it is well known that many of the inoculated persons, including even a 

 number of those who received more than one injection of the prophylactic, 

 have contracted the disease. Thus, the Indian Plague Commission found 

 that some individuals who during two years had received four injections 

 of the prophylactic, fell victims to pest; and, on the other hand, as many 

 as 8 per cent of the inoculated in one district, Bulsar, contracted the 

 disease. In 1902 it was the intention of the Indian government to 

 inoculate the inhabitants of a province containing about six millions 

 of people with this prophylactic. However, the work was discontinued 

 owing to 18 deaths from tetanus which occurred among the inoculated 

 shorty after the project was undertaken. 



It is important in discussing the value of Haffkine's inoculations to 

 consider the work of Kolle and Otto 24 on the immunization of guinea 

 pigs with Haffkine's prophylactic. These authors conclusively showed 

 that guinea pigs could not, except in rare instances, be immunized against 

 pest infection by the use of this prophylactic and their experiments led 

 them to emphasize the fact that if large and repeated doses of the killed 

 pest organism failed to . immunize such small animals as guinea pigs, 

 it seemed unreasonable to expect very favorable results in man from 

 such a method, particularly since the amount of the bacteria inoculated 

 in human beings is so much smaller in proportion to the body weight. 



However, the subject with which I was at first most concerned was 

 work which would lead to a decision as to the most effective method 

 of inoculation against pest and this it seemed could best be carried out 

 by experimental studies on animals. 



It therefore was from this standpoint that I decided first to investigate 

 the subject. 



-' Zisclir. f. Hi/g. u. InfectionskranJch., Leipz. (1903), 45, 



