312
Multiplication of B. Anthracis and Cl. Chauvœi
of added organisms remained alive at 5°C, while at 10°C. only 0.07 per cent
survived. In the case of soil, Martin [1897-98] found that Bact. typhosum
would grow at 37°C. in moist sterile soil containing much organic matter and
that some growth also occurred at 15°-19°C. In sandy or peaty, unmanured,
sterile soil, there was no growth, even at 37°C. Mair [1908], on the other hand,
could get no evidence of Bact. typhosum multiplying in either sterilized or
unsterilized soil. In some samples, but not in all, the organism died out much
more rapidly if the soil had been previously autoclaved, apparently owing to
the production of bactericidal substances during sterilization. Harvey
[1929] quoted the important observation of a urinary carrier who was caused'
to micturate on to a patch of soil in a dark hut ; typhoid organisms could not
be isolated from the soil much beyond 24 hours. With V. cholerae, there is
stated to be no support for the view that the epidemic prevalence of the
disease depends on the vitality of the organism outside the body ; some
natural waters for example are well known to be rapidly lethal. The subject
is dealt with in a recent paper by Read, Singh, Seal and Bose [1939], to which
reference may be made for further particulars.
The following remarks concern bacteria of importance in animal patho-
logy. Organisms of the Clostridium group are regarded as primarily sapro-
phytic in nature, living in the intestine of animals and proliferating also in
decaying animal and vegetable matter. It is of interest to note that at least
one species, viz. Cl. botulinum, is common in virgin soil and hence one might
expect it to be capable of multiplying therein. Bull [1939] refers to the
possibility of Cl. welchii type D growing in soil rich in organic matter and
under favourable temperature and moisture conditions, and considers that
in this possibility lies an explanation of outbreaks of ovine entero-toxaemia.
Fildes [1929], writing of tetanus, says, ' It is generally assumed that in the
soil the bacteria are present as spores, but the possibility of vegetation under
certain circumstances has never been considered '. As to Corynebacteria,
Carne [1932] found that C. ovis will grow readily at 37°C. in the autoclaved
faeces of sheep which had been fed on certain diets. The author was ' not
successful in carrying out experiments with unsterilized faeces '. Bull and
Dickinson [1933] also believe that C. ovis may grow in soil and accumulated
vegetable matter at seasons when the moisture conditions are favourable
There was no direct evidence of this and the reason for their belief was the
ease with which soil from places where ovine caseous lymphadenitis is enzootic
will sometimes infect guinea-pigs. The importance of soil reaction in respect
of survival of E. rhusiopathiae has been pointed out by Hesse [1924], survival
being considerably greater in alkaline than in acid soils.
TECHNICAL DETAILS
Soil
For most of the experiments, soil from the Institute inner area at Muktes-
war was used. The bulk samples (A, B and C) were taken from a not obvious-
ly manured plot at depths varying from 3 in. to 12 in. For certain experi-
ments, soil samples from the Imperial Agricultural Research Institute and
from Madras were used. The nature and analysis of the soils used is shown in
Table I.