?
within the incubation period, does not decrease the chance of recovery,-as has
been stated by some eminent authorities,-but on the contrary diminishes the
liability to death. This latter conclusion does not rest merely on this instance
but on evidence that has been accumulating during the past three years, as the
result of many similar investigations in all parts of the country where these
prophylactic inoculations have been tried. (Vide Dhárwár, p. 18, supra.)
24. Yeroada Jail.-It has been on several occasions observed that when
a population living more or less under control,-such as a regiment, or
the inmates of an asylum or jail,-are entirely or almost all inoculated, the
epidemic of plague at once stops. Again this sequence of events was witnessed
lately in this large central jail situated near the town of Poona. The first case
occurred on the 5th of October 1900, and the last indigenous case on the 17th of
the same month. A solitary imported case afterwards occurred on the 26th October in an under-trial prisoner newly admitted from Poona where plague was prevalent.
Cases of plague occurred on the following dates, viz.:-
1 on the 5th October.} 
All in prisoners who had been some months in jail.
1 „ „ 12th „ }

2 „ „ 17th „ }

Total  4 cases.

Inoculation was begun on the 10th October, and was practically complete by
the 17th, when 1,658 prisoners had been operated on. Of the above 4 cases, all
died but one, who had been inoculated 4 days previous to attack. The other 3
were attacked before they could be inoculated. Since then, no more indigenous
cases have occurred.
From the above observations it may be taken as proved-
(a) That inoculation is harmless.
(b) That when given in the incubation stage (i.e., before signs of plague
are apparent) it has-in many cases at least-the power of aborting the
disease.
(c) That inoculation confers a high degree of immunity from plague,
and so reduces very greatly the number of attacks.
(d) That when, in spite of inoculation, a person is attacked, his chances
of recovery are very greatly increased.