the rod, which is enlarged so that the rod itself appears more or less
club-shaped. What has already been stated concerning the significance of
the spore of the anthrax bacillus applies equally well to these bodies.
They resist destructive agents for a considerable time, and may still
produce disease when inoculated after several years of drying. This fact
may account for the occasional appearance of blackleg in stables. In order
to meet the requirements for the development of the spores, which takes
place only in the absence of the atmosphere, it is necessary that the wound
be very small and deep enough to penetrate the subcutaneous tissue.

Several observers have found this organism in the mud of swamps. By placing
a little of the mud under the skin, the disease has been produced.

Since the disease may be produced by placing under the skin material
containing the specific bacilli and spores, it has been assumed that cattle
contract the disease through wounds, principally of the skin, or very
rarely of the mouth, tongue, and throat. Slight wounds into which the virus
may find access may be caused by barbed wire, stubbles, thorns, briers,
grass burs, and sharp or pointed parts of feed. Infection by way of
digestive tract is also probable.

_Symptoms and lesions._--The symptoms of blackleg may be either of a
general or of a local nature, though more frequently of the latter. The
general symptoms are very much like those belonging to other acute
infectious or bacterial diseases. They begin, from one to three days after
the infection has taken place, with loss of appetite and of rumination,
with dullness and debility, and a high fever. The temperature may rise to
107 deg. F. To these may be added lameness or stiffness of one or more limbs,
due to the tumor or swelling quite invariably accompanying the disease.
After a period of disease lasting from one to three days the affected
animal almost always succumbs. Death is preceded by increasing weakness,
difficult breathing, and occasional attacks of violent convulsions.

The most important characteristic of this disease is the appearance of a
tumor or swelling under the skin a few hours after the setting in of the
constitutional symptoms described above. In some cases it may appear first.
This tumor may be on the thighs (hence "blackleg," "black quarter"), the
neck, the shoulder, the breast, the flanks, or the rump; never below the
carpal (or knee) and the hock joint. It