F. C. MINETT AND M. R. DHANDA 311
From a perusal of veterinary literature, it may be concluded that there
is much uncertainty as to whether pathogenic organisms which find their
way into the soil actually multiply therein. It is well known, on the other
hand, that many of the common soil bacteria have an antagonistic action
upon bacteria, pathogenic or otherwise. A familiar and classical example is
the inhibitory effect of ' bacillus pyocyaneus ' upon the anthrax bacillus but
many other bacteria have a similar action. For instance, Isabolinski and
Sobolewa [1934] have recently emphasized that Bact. coli is antagonistic
to B. anthracis both in vivo and in vitro ; when both are sown together in
broth, coli alone grows. Proteus vulgaris and also mixtures of streptococci
and staphylococci are likewise antagonistic. As Lewis [1929] and Waksman
and Woodruff [1940] point out, a rich literature has now accumulated on the
subject of bacterial antagonism and many efforts have been made to deter-
mine the properties and nature of the antagonistic substances produced.
Blackquarter
Blackquarter also is referred to as a soil disease and its prevalence in
certain countries is stated to be similar, in many respects, to that of anthrax
and to be related to particular types of soil. Thus, Hunziker [1927] states
that in Switzerland outbreaks of blackquarter are related to the chalk content
of the soil. Viljoen and Scheuber [1926], writing of blackquarter in South
Africa, state that, although the disease occurs in all parts, it tends to be
regionally distributed, being more prevalent in low-lying areas. There is
no reason to believe that the disease in South Africa is connected with any
special kind of soil but its occurrence is seasonal, being at its worst during
the spring and early summer months and especially after heavy rains. The
organism is generally believed to be a facultative parasite, capable of exist-
ing and multiplying in the soil of certain localities, but, as the authors state
' no experimental evidence to prove this contention or to show how long the
organism can exist outside the animal body has ever been advanced ' Seddon
and Edgar [1930] say that, although the soil of damp or marshy areas is usually
regarded as the normal habitat of Cl. chauvœi, this opinion has not, apparently,
been confirmed bacteriologically. They themselves have never isolated the
organism from the soil of localities where blackquarter is enzootic. Probably
the organism is confined to spots where the carcases of animals dead of the
disease have disintegrated.
It is not perhaps altogether out of place to refer here to some of the
work which has been done on the behaviour of other pathogenic organisms
in soil and water. Towards the end of the last century, a considerable amount
of work was carried out on this subject and the position as regards water is
thus summarized by Henry [1929], " Where the organic content remains at a
high level, as in heavy pollution with sewage, the organisms that are parti-
cularly adapted to a parasitic existence in the bodies of animals and plants
may survive for some time, but with dilution and oxidation they tend to die
out and disappear, leaving only the ordinary harmless water bacteria to take
their place ". With regard to Bact. typhosum and the effect of temperature
on its survival in water, Houston [1911] noted that after a week 14 per cent