PROPHYLAXIS. 489 



fornia, the work of extermination of squirrels, rats 

 and fleas has been carried on extensively by the 

 U. S. Public Health and Marine-Hospital Service. 



The vaccine of Haffkine has been used exten- vaccines. 

 sively in India. The Indian plague commission 

 found that the incidence of disease and the mor- 

 tality were lower among the inoculated than the 

 uninoculated, although many of the inoculated 

 contracted the disease in a benign form. The vac- 

 cine consists of bouillon cultures which have grown 

 for six weeks with stalactite formation (see above), 

 then killed by exposure to a temperature of 65 C. 

 for one hour; from 0.5 to 3.5 c.c. are injected, ac- 

 cording to the age and size of the individual. One 

 or more subsequent injections may be given. The 

 local and general reactions are of moderate sever- 

 ity. Protection becomes manifest only several 

 days after the inoculation and may persist for 

 many weeks or months. The vaccine recommended 

 by the German commission consists of two days' 

 old agar cultures which have been killed by heat 

 (65 C. for one hour). Lustig and Galeotti utilize 

 the toxic precipitate described above as a vaccine. 

 Terni and Bandi inoculate rabbits or guinea-pigs 

 intraperitoneally with the plague bacillus and 

 after or just preceding death collect the peritoneal 

 exudate, in which the organisms are allowed to pro- 

 liferate still further for twelve hours. The bacilli 

 are then killed at a low temperature, and this 

 fluid, after an addition of a preservative, consti- 

 tutes their vaccine. Although the last three vac- 

 cines have proved of value in animal experiments, 

 they have not as yet been used extensively in man. 



Besredka and Shiga recommend the use of mixed 

 active and passive immunization, as suggested in 



