230 STRONG AND TEAGUE. 



that of 20 other individuals who were inoculated at the same 

 time none became infected. 



At Fuchiatien, 439 individuals were inoculated with Haffkine's 

 vaccine and with antiplague serum. Sixteen individuals received 

 three inoculations, two of Haffkine's vaccine and one of serum. 

 None of these became infected. Thirty individuals received two 

 injections, either with Haffkine's vaccine or with Haffkine's 

 vaccine and serum. None of these, also, became infected. Of 

 393 individuals who were vaccinated once with Haffkine's vac- 

 cine, 4 died of plague, 1 eight days, 1 ten days, 1 eighteen days, 

 and 1 thirty-two days after inoculation. The same comment 

 applies to these statistics, namely, that we have no evidence as to 

 how many of the 439 individuals who were inoculated were 

 subsequently exposed to infection and how many protected them- 

 selves by the use of masks. 



Approximately 14,000 individuals were inoculated with killed 

 cultures of the plague bacillus, during the epidemic, but the great 

 majority of these individuals were never exposed to plague in- 

 fection. Therefore, we have no positive evidence as to what pro- 

 tection was conferred upon them by inoculation. The only defi- 

 nite conclusion which, it appears, we were justified in drawing 

 from the statistics obtained from the epidemic is that prophy- 

 lactic inoculations, by means of dead cultures, have sometimes 

 been ineffective in preventing pneumonic-plague infection. Some 

 individuals, inoculated twice, and some even three times, have 

 contracted the disease. 



From the evidence presented before the International Plague 

 Conference, held in Mukden in April, 1911, it was resolved by 

 the Conference that the statistics, which were collected during 

 the epidemic, did not allow of any definite conclusion about the 

 value of active prophylactic inoculation against pneumonic plague. 

 Nevertheless, the Conference further resolved that, as the statis- 

 tical evidence pointed to the conclusion that some degree of 

 protection is conferred against bubonic plague by the use of 

 prophylactics, therefore, there were a priori grounds for the use 

 of protective inoculation against pneumonic plague. 



The Conference, therefore, advised that experiments on the 

 protective inoculation of animals should be carried on and the 

 immunity of the animals tested by their exposure to infection to 

 pneumonic plague by inhalation, in order to find out which pro- 

 phylactic could be best used against pneumonic plague, and, if 

 another outbreak of this disease should occur, that dead bacil- 

 lary prophylactics, Lustig and Galeotti's nucleo-proteid, and 

 Strong's method of vaccination, with a living attenuated culture. 



