March, 1953]
J. M. LALL AND N. C. SEN 29
maintained perfect health and was destroyed 94 days later. On post-mortem
examination a hard tumour like mass about the size of a walnut with a central cavity
containing a thin creamy yellow pus was seen at the site of inoculation. The asso-
ciated inguinal group of glands appeared to be slightly enlarged and cystic. No
lesions were observed in any of the internal organs. Smear from the pus showed
large numbers of degenerating bacilli, which were long, slender, twisted or curved.
These, when grown on suitable media yielded a fair number of colonies showing that
some of the bacilli were still viable. However, there was nothing to indicate that a
progressive disease had been set up.
Irwin and O'Connell [1943] made experiments in guinea-pigs, which had been
infected with virulent human tubercle bacilli at varying periods after vaccination
with vole bacillus. They observed that all the controls showed severe tuberculosis
six weeks after they had been infected, whereas the vaccinated animals showed
less severe tuberculous lesions. The severity of lesions decreased in the vaccinated
animals as the interval between vaccination and artificial infection increased.
Corper and Cohn [1943] made a comparative study of the immunising effects
of the vole bacillus, B.C.G. and avirulent human tubercle bacilli in guinea-pigs.
A similar infecting dose was used in each case. To assess the degree of infection
all the animals were killed sixty days after they had been vaccinated. They con-
cluded from these experiments that the vole bacillus sets up immunity against
infection with human tubercle bacilli which is comparable to that produced by
avirulent human tubercle bacilli or B.C.G.
Sahai [1943 to 1944] carried out an experiment to test the value of the vole
vaccine in preventing tuberculosis in calves. Sixty-three, four to five months old
calves, of Hariana breed, negative to double-intradermal tuberculin test, were
divided into groups of 39 principals and 24 controls. The principals were adminis-
tered varying doses of the vole bacillus (strain LV 285) suspended in saline and
were mixed with controls. Five months later all animals were administered by
mouth 8.0 mgm. of mixture of three virulent strains of bovine tubercle bacilli in 2
ml. of saline. The strains used for the immunity test were of standard virulence
for rabbits. After three months the controls were tuberculin tested and all but
two proved positive. Almost exactly ten months from the starting of the experiment
all the remaining calves were again tuberculin tested and a number killed. On
post-mortem examination it was observed that the incidence and extent of infection
in the controls was so. meagre that little could be learnt of the value of the vaccine.
However, it seemed that the principal had developed, a faint immunity.
Wahlgren and his co-workers [1944] made a comparative study in guinea-pigs
using vole bacilli and B.C.G. as vaccines. They found that ten of the twelve controls
infected with virulent human tubercle bacilli died of generalised tuberculosis at
varying periods (67 to 140 days). Four out of fourteen animals vaccinated with
B.C.G. three months before infection died of tuberculosis at periods varying from
122 to 150 days. All the ten animals which had received vole bacilli three months
before infection were alive after 153 days and all the surviving animals which were
killed showed lesions of tuberculosis in the regional lymph glands and in various
internal organs; these changes were less extensive than those of the controls. They
also noted that guinea-pigs vaccinated two, twelve and twenty-four days before