2                   THIRD SPECIAL REPORT ON THE

lowing paragraphs, the lymph sent out from this office has been procured
from Calcutta itself. The virus has been of unexceptionable quality,
and, during the cold months, has been used most successfully. The virus
throughout the year has been kept in a high state of perfection, and no
vesicle which was not typically perfect has ever been used to provide
lymph for transmission to another station. In minor characters, the
vesicles in January differ somewhat from those in July, but in all essen-
tial characters they are precisely similar. Their contents I believe to
be identical in all important particulars. Arguing from analogy, I feel
sure that if simultaneous vaccinations were practised with the virus
procured in Calcutta at different seasons, at any place where climate
did not lead to the slight alterations in the appearance of the vesicles
alluded to, the vaccinations, after very few transmissions, would be found
to be not distinguishable, the one set from the other.

Degeneration
of Vaccine.

4. In looking into the annals of vaccination in India, I find
doubts have been expressed as to the efficacy of Indianized lymph. No
facts have been brought forward in support of such allegations, and I
look upon them as entirely groundless. The tendency of the virus to
degenerate and cease to produce vaccinia, seems to have been the founda-
tion on which such a hypothesis has been brought forward. Two ques-
tions are here involved, which, if accuracy is desired, must be kept
separate. The virus, it is true, degenerates in the sense of being unable
to keep up its kind, in consequence principally of superadded in-
flammatory results. When such changes first begin, the virus may, by
careful management, be brought back to a state of perfection. Even in
a single transmission it may become degenerated beyond recall; at
times the change may be more gradual. The moment this transforma-
tion has taken place it is no longer vaccine. A succession of degenerated
vaccinations is not kept up. If a vaccinator attempts from such a
source to keep up a lymph supply he fails. Once or twice he may
succeed in creating inflammatory processes of sorts; but his power of
effecting even this soon stops. No favouring change of climate can
ever bring back such lymph to the characteristic normal vaccine. The
virus, on the other hand, cannot degenerate in the sense of becoming less
protective against variola, and still continuing to be vaccine. The
virus of vaccinia may have subsidiary characteristics impressed on it,
some of which are salutary, while some are prejudicial; but in its great,
essential feature, the fact that it is variola deprived of its secondary
eruption, vaccine as long as it is vaccine remains the same. The
differences between the various forms of small-pox are very great