44 



PLAGUE 



addition of 0*5 per cent, carbolic acid. Cultures are made in 

 peptonized broth to which a small amount of oil is added. This 

 floats on the surface, and serves as a point of attachment for the 

 characteristic " stalactites." The flasks are kept at the ordinary 

 temperature (of Bombay about 27 C.) and shaken occasionally, 

 to break up the stalactites. Incubation lasts five to six weeks. 

 The vaccine is sterilized at 65 C. for one hour. The dose is 

 2-5 c.c. Constitutional and local symptoms of moderate severity, 

 and lasting for a few days, are produced, but the patient is as a 

 rule able to follow his ordinary occupation. The immunity 

 seems to be developed quite quickly, so that there is no reason to 

 fear any ill-effects from the injections when the patient is actually 

 exposed to plague, and perhaps even infected. According to 

 Bannerman, the protection is developed in twenty-four hours, and 

 asts about eighteen months. 



Of the value of the method there can be no doubt, and statistics, 

 both those on a large scale and those dealing with communities, 

 some of whom are vaccinated and some not, prove clearly that 

 the treatment lowers the likelihood of infection, and also the case- 

 mortality. Thus, in twelve districts in the Punjab in which 

 plague was raging in the winter of 1902-03 the following results 

 were obtained : 



With regard to the second group of statistics, the experience in 

 Umarkadi Gaol may be quoted, as one out of many. Half the 

 prisoners, selected purely by chance, were inoculated, and all 

 lived together under exactly the same conditions. Some of each 

 group were liberated, and of the remainder there were 127 non- 

 inoculated, with 10 cases and 6 deaths, and 147 vaccinated, with 

 3 cases and no death. 



The German Commission recommended the use of vaccines 

 prepared from two-day-old agar cultures, sterilized by heat. This 

 is more easily and quickly prepared than Haftkine's fluid. 



The combined method (use of vaccine and serum) has been 



