PLAGUE 191 



individuals had been vaccinated, and of these 339, i. e., 0.8 per cent., 

 died. Of the non-vaccinated during the same period 2395 succumbed, 

 i. e., 5 per cent., as compared with the total number of inhabitants. 

 During the week of September 21 to September 27, when all 

 the inhabitants, with the exception of 603, had finally been vac- 

 cinated there were among the 38,712 protected individuals only 

 20 deaths, while of the 603 non- vaccinated persons 58, i. e., 9.61 

 per cent., died. 



Quite striking also are the following data: In three villages there 

 occurred 13 cases among 365 vaccinated persons, with 3 deaths, 

 while of the 363 non-inoculated individuals 49 were taken ill and 38 

 died. In Bombay there developed 18 cases of the disease among 8200 

 vaccinated persons, with 2 deaths (mortality 11.1 per cent.), while the 

 general mortality from the disease was over 90 per cent. 



These few examples will, I think, suffice to illustrate the real value 

 of vaccination against plague, but it will be noted, as in anticholera 

 vaccination, that the protection is not absolute. The mortality 

 among the vaccinated is so much lower, however, i. e., 11 to 41 

 per cent., as compared with 50 to 92 per cent, among the non- vac- 

 cinated, as observed in different localities, that this factor in itself 

 would establish the value of the procedure, and as a matter of fact 

 all the different commissions, which have investigated the Haffkine 

 method, have expressed themselves in this sense. 



The Duration of Protection. This is estimated at several months, 

 after which the vaccination must be repeated, if danger of infection 

 still exists. 



Preparation of the Vaccine (Haffkine). Haffkine makes use of 

 bouillon cultures which have been allowed to grow for six weeks at a 

 temperature of 25 to 30 C. The bouillon is prepared as follows: 1000 

 grams of lean (goat) meat are passed through a meat-hashing machine, 

 and are digested for three hours with 125 grams of hydrochloric 

 acid (concent.) in the autoclave, at a pressure of three atmospheres. 

 The resultant material is filtered and diluted with water, so that 

 the content in proteins shall be 1 per cent, (approximately seven 

 volumes of water). The broth is then neutralized with calcium 

 carbonate, and sodium chloride added to make it of physiological 

 strength. It is then sterilized and filtered into suitable flasks (to a 

 height of 7.5 cm.), into each of which a few drops of olive oil or 

 butter fat (sterile) are further added, to serve as floats from which 



