244 POPULAR SCIENCE MONTHLY. 



reaction varies in different individuals, but a temperature reaching 102° 

 and above in at least thirty per cent of those inoculated has been found 

 to indicate a good material. In the cholera, rabies and smallpox 

 vaccines, the microbes being employed in a living state, it was essential 

 to fix the strength of the vaccine, for otherwise it was impossible to 

 predict the behavior of the microbe when injected into the system. 

 In the case of the plague prophylactic the activity of the microbes 

 is arrested before it is inoculated, and the effect can be regulated, as 

 mentioned above, by simply measuring up the doses in the same way 

 as is done with any chemical drug. 



The expectation formed when devising the plan for the plague 

 prophylactic has been very fortunately justified, and an advance on the 

 results from the cholera vaccines was obtained; but I can not yet say 

 certainly whether this favorable result is indeed due to the particular 

 provisions which I had made for obtaining it. 



The effect of the plague prophylactic was first tested at the Byculla 

 Jail, in Bombay, when the epidemic reached that establishment. From 

 the first day after the inoculation till the end of the outbreak there 

 were in the jail twelve cases and six deaths among one hundred and 

 seventy-two uninoculated inmates, and two cases, with no deaths, among 

 one hundred and forty-seven inoculated. A year later, almost exactly a 

 similar result was observed when the plague attacked the so-called 

 Umarkhadi Common Jail, in Bombay. In this case after the inocula- 

 1 ion i here were ten cases and six deaths among one hundred and twenty- 

 seven uninoculated inmates, and three cases, with no deaths, among 

 one hundred and forty-seven inoculated. These and other observations 

 show that the vaccine for the plague begins to exercise its effect within 

 some twenty-four, hours after inoculation; that it is useful even in the 

 case of persons already infected; that it is therefore applicable at any 

 stage of an epidemic. Numerous* further observations were soon col- 

 lected on the working of the system. 



At the small village of Uudhera, of the Baroda feudatory state, 

 where plague broke out, inoculation was applied to a half of each 

 family, the other half remaining uninoculated. After that there were 

 twenty-seven cases and twenty-six deaths among sixty-four uninocu- 

 lated, and eight cases, with three deaths, among seventy-one inoculated 

 of the same households, the proportionate difference in mortality being 

 over eighty-nine per cent. There followed observations on a far 

 larger scale, demonstrating that the mortality of the inoculated, com- 

 pared to that of the non-inoculated, was on an average between eighty 

 and ninety per cent less. Sometimes this reduction reached ninety 

 per cent. In the Punjaub, in a village called Bunga, there occurred, in 

 two hundred and eighty-one not inoculated, ninety-seven cases of 

 plague and sixty-five deaths, while among seventy-four inoculated there 



