he power of
indefinite multiplication, and in the bodies of infected animals they
produce death by rapidly increasing in numbers and producing substances
which poison the body. In the blood they multiply in number by becoming
elongated and then dividing into two, each new organism continuing the same
process indefinitely. Outside the body, however, they multiply in a
different way when under conditions unfavorable to growth. Oval bodies,
which are called spores, appear within the rods, and remain alive and
capable of germination after years of drying. They also resist heat to a
remarkable degree, so that boiling water is necessary to destroy them. The
bacilli themselves, on the other hand, show only very little resistance to
heat and drying. It has long been known that the anthrax virus thrives best
under certain conditions of the soil and on territories subject to floods
and inundations. The particular kinds of soil upon which the disease is
observed are black, loose, warm, humous soils; also those containing lime,
marl, and clay, finally peaty, swampy soils resting upon strata which hold
the water, or, in other words, are impervious. Hence fields containing
stagnant pools may be the source of infection. The infection may be limited
to certain farms, or even to restricted areas on such farms. Even in the
Alps, more than 3,000 feet above sea level, where such conditions prevail
in secluded valleys, anthrax persists among herds.

Aside from these limitations to specific conditions of the soil, anthrax is
a disease of world-wide distribution. It exists in most countries of
Europe, in Asia, Africa, Australia, and in our own country in the lower
Mississippi Valley, the Gulf States, and in some of the Eastern and Western
States. It seems to be gradually spreading in this country and every year
occurs in new districts.

Meteorological conditions also have an important share in determining the
severity of the disease. On those tracts subject to inundations in spring a
very hot, dry summer is liable to cause a severe outbreak. The relation
which the bacillus bears to these conditions is not positively known. It
may be that during and immediately after inundations or in stagnant water
the bacilli find nourishment enough in the water here and there to multiply
and produce an abundant crop of spores, which are subsequently carried, in
a dry condition, by the winds during the period of drought and disseminated
over the vegetation.