CALCUTTA AND THE SUBURBS.
5
transmission, and they do not differ in the most minute particular from the vaccinations
carried on from other humanized virus. At first a few more of the points of insertion seemed
to fail in the case of transmissions from one of the children vaccinated from the calf, but as
no such peculiarity was noticed in the case of the vaccinations from the other child, I conclude
the tendency was accidental.
Two children were vaccinated from crusts removed from a calf; in one the vaccination
succeeded, in the other it failed. From virus shut up in tubes and used as soon as it could be
carried to the houses of the children the following results were obtained :—
In the cases of 33 children so vaccinated only 10 successful cases resulted.
Sixty-six points of insertion were made, and out of these at only 16 points vesicles result-
ed. I hesitate to accept that the enormous percentage of failures above shown is insepar-
ably connected with all animal virus shut up in tubes, but am convinced that though doubtless
by investigating the cause of failure some improvement might be secured, a very large
percentage of failure must be looked for from the use of such virus,—a percentage so great as
to render it highly inadvisable to use the virus in this way for general vaccination. In
vaccinating from this tube lymph some of the vesicles were found to be small, and the vaccin-
ation to be rather delayed.
10. Re-vaccination from the calf.—The most satisfactory part of the experiment with
animal virus consisted in the vaccination of 62 persons who had previously been protected
and the result is a very important one.
Out of these 62, 35 children had last year been re-vaccinated, and of them in only one
instance did the vaccination from the calf take. In this case the result was a very modified
success, showing that a very slight susceptibility to small-pox had been regained during the
year.
Of the remaining 27, in 5 the vaccination proved quite as successful as if no protection
had previously been given, while in 8 a partial success resulted. Two of the successful
cases were in adults who had had small-pox, and one in a woman who had been successfully
inoculated in childhood ; the remaining two successes were in children who had been vaccinated
in infancy. The majority of these twenty-seven cases had been re-vaccinated in 1864.
An attempt has been made on very insufficient grounds to establish a belief that virus
direct from the cow succeeds in producing vaccinia when used for re-vaccination in a much
greater proportion than when lymph from a child is used. Had it had any such power, it
would at once have become apparent while vaccinating the 35 children who had last
year been re-vaccinated. That the virus from the calf was in every respect perfect, is
established by the fact of its infecting such a large number of persons who had only once in
their lives received that amount of protection which an attack of small-pox, inoculation, or a
single vaccination, can afford. That when such an active virus was used—a virus falsely con-
sidered by some as superior to humanized lymph—34 children should have proved completely
insusceptible to its influence, is a most important fact in the annals of Indian vaccination.
It shows that the virus in ordinary use is as certain in protecting from small-pox as vaccine
can possibly be, and that in spite of the difficulties attending vaccination in India, the virus
can be kept up through a long series of years to this unimpaired state of excellence. As far
as can be proved by a single limited experiment, the above fact shows that the vaccine used
last year, after having passed through such a long series of transmissions through the human
system as to be practically unable to be counted, has not in the least degenerated. In these
34 cases re-vaccinated last year with our old stock of lymph. the virus direct from the calf
which had never previously been passed as vaccine through the human system produced no
more effect than if so much white of egg had been used to vaccinate with. I am glad to
be able to bring forward this proof, in addition to others that I have recorded, that vaccination,
when properly conducted, is worthy of great confidence being placed in its protective efficacy.
11. Conclusions with regard to animal virus.—The following conclusions briefly summa-
rize the opinions which I have formed in connection with animal vaccination, and will
probably be deemed sufficient without a detailed report:—
(1) The vaccinations with animal virus were found in no way to differ from those
performed with the old stock of lymph;
(2) That the success attending the use of virus direct from the calf, or on its first trans-
mission, was so great, as to justify extensive vaccination being practised in this
way;
(3) That in the event of small-pox rendering it necessary to vaccinate large numbers of
persons, for whom sufficient numbers of children cannot be persuaded to furnish
virus, the aid furnished by vaccinating calves would prove a very efficient one ;