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 inoculation 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 collected 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 uninoculated, 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, compared 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