MUKTESAR, FOR THE TWO YEARS ENDING THE 31ST MARCH, 1924 33
liver with not quite so much certainty, and the blood probably; the
other films were undoubtedly negative (September 1922).
A curious discovery of considerable importance was then made.
The sensitiveness of the rinderpest virus to varying concentrations of
carbolic acid was being tested, and it was found that over one-half
per cent. of this substance rendered the virus inert in a day at body tem-
perature. It was thought that perhaps the rinderpest organism might;
not have been actually destroyed at this concentration, but that it
might merely have lost the property of virulence for cattle; dark-ground
examination of material showed bodies—which are now realized to be
merely colloidal protein particles—but which then encouraged the ex-
ploitation of the possibility. It was thought that the virus after having
lost its pathogenecity for cattle might still maintain a behaviour towards
rabbits just as if it had not undergone this degradation. As large quanti-
ties as possible of the carbolised blood were, therefore, injected intraven-
ously into rabbits and tested simultaneously as to absence of virulence
upon cattle. After a few passages the pronounced febrile reaction of
, rinderpest became manifest in the rabbits, and their blood gave rinder-
pest to cattle. These tests were then repeated upon rinderpest blood
stored under paraffin at body temperature for three months, and diluted
very extensively with peptone water or dilute horse serum, so as to
lose its virulence for cattle; again intensive passage through rabbits
brought back the virulence for cattle, so that the causal agent was not
in reality destroyed but merely rendered inert or degraded in its powers
for invading its natural host.
Serious attempts were then made at cultivation, and at first these
were followed by a very ready success, which could not be readily re-
peated in subsequent experiments. It was thought that if the virus
was a minute spirillary organism it would probably work its way through
the walls of a porous closed candle such as is used for bacterial filtra-
tion and be trapped in a state of purity in the interior. With strict
precautions, small lengths of closed Chamberland candles containing
salt solution or peptone water were placed inside the peritoneal cavities
of cattle, which were then infected with rinderpest. At the height of
the reaction the candles were carefully withdrawn and dropped into
tubes containing sterile molten vaseline, which was then allowed to set,
and the tubes incubated. Candles were withdrawn for the examination
of their contents from time to time; stained preparations showed a
development during succeeding days of short vibrionic structures to
distinct leptospirillary forms. A feature of the stained forms was that
they possessed feeble powers of retaining the stain and generally became
decolourised in a day or two. The candle fluid was avirulent for cattle,
and the injected cattle subsequently possessed no immunity. Only in
one case did a bull show a distinct fever, several days after injection,
and it was then immune to rinderpest. Passage of candle fluid intraven-
ously through the rabbit restored it to its state of virulence for
the ox.
D