MUKTESAR, FOR THE TWO YEARS ENDING THE 31ST MARCH, 1924 39
occurred, however, when the animals were submitted to massive in-
jections with very virulent material. The indications at the close of
the period under report were that the most economical procedure would
be to submit the animals initially to simultaneous inoculation with a
large dose of good protective serum and a suitably, relatively large
quantity of highly virulent antigen.
In the course of experiments upon the rate of development of agglu-
tinating powers by the serum of infected animals, it was found that the
serum of many " normal" buffaloes possessed an unexpectedly high
agglutinating titre, and that the apparent " natural" immunity of the
species ran parallel to the degree in which this property was demonstra-
ble in the blood serum.
Experiments in connection with the effects of " passage " upon the
virus were in active progress at the end of the period under report. Pas-
sage of a virus which had become very greatly degraded in its pathogenic
properties by prolonged cultivation in artificial media, (a) through cattle
or buffaloes exalts it for bovines, (b) through normal susceptible rabbits
(not previously affected with pasteurellosis) exalts it for rabbits, but
attenuates it further for bovines, and (c) through rabbits that have passed
through a natural outbreak of " rabbit septicæmia " attenuates it for
both rabbits and bovines. The serum prepared for use against bovine
hæmorrhagic septicæmia had no effect in mitigating an outbreak of
rabbit pasteurellosis; the last named condition appeared to be set up
by strains of organisms that were serologically identical with each other
but different from those of bovine hæmorrhagic septicæmia. The re-
searches on this disease were executed nearly entirely by Mr. Bennett.
(d) Contagious Bovine Abortion. During the two years under report
over 900 samples of serum from cattle maintained at the Government
Military Dairy Farms were tested, by means of the agglutination test,
for evidence as to infection with the common form of contagious bovine
abortion, due to Bacillus abortus Bang. The results indicated that
about 50 per cent. of the breeding animals on these establishments were
infected, and the rate of clinical abortion was very high (over 20 per cent.).
In order to compare the rate of infection and morbidity among Indian
cattle maintained in the open, in the usual conditions in which cattle
are kept in India, Mr. Bennett was deputed to conduct investigations
in the Punjab during the cold weather 1923-24, upon the animals in
several " grantee " herds. About 2,000 samples of serum were tested,
and the results indicated an infection rate of about ten per cent., and
a specific abortion rate that was almost, if not entirely, negligible.
Some interesting information is being collected with regard to the varying
susceptibility of the different breeds of cattle maintained at the Govern-
ment Dairies; it would appear that buffaloes possess a high degree of
resistance, and indigenous cattle are less susceptible to clinical abortion
than are cattle with a considerable admixture of European blood.
Vaccination was attempted systematically during the period under
report upon the Lucknow Dairy. The first year's results, after vaccina-
tion with an English strain of Bacillus abortus that had been maintained