the survival of the infecting germ.

_Cause._--It is no longer to be doubted that the microbes found in the
inflammatory product are the true cause of erysipelas, as by their means
the disease can be successfully transferred from man to animals and from
one animal to another. This transition may be direct or through the
medium of infected buildings or other articles. Yet from the varying
severity of erysipelas in different outbreaks and localities it has been
surmised that various different microbes are operative in this disease,
and a perfect knowledge of them might perhaps enable us to divide
erysipelas into two or more distinct affections. At present we must
recognize it as a specific inflammation due to a bacterial poison and
closely allied to septicemia. Erysipelas was formerly known as surgical
when it spread from a wound (through which the germ had gained access)
and medical, or idiopathic, when it started independently of any
recognizable lesion. Depending as it does, however, upon a germ distinct
from the body, the disease must be looked upon as such, no matter by
what channel the germ found an entrance. Erysipelas which follows a
wound is usually much more violent than the other form, the difference
being doubtless partly due to the lowered vitality of the wounded
tissues and to the oxidation and septic changes which are invited on the
raw, exposed surface. As apparently idiopathic cases may be due to
infection through bites of insects, the small amount of poison inserted
may serve to moderate the violence.

This affection may attack a wound on any part of the horse's body,
while, apart from wounds, it is most frequent about the head and the
hind limbs. It is to be distinguished from ordinary inflammations by its
gradual extension from the point first attacked, by the abundant liquid
exudation into the affected part, by the tension of the skin over the
affected part, by its soft, boggy feeling, allowing it to be deeply
indented by the finger, by the abrupt line of limitation between the
diseased and the healthy skin, the former descending suddenly to the
healthy level instead of shading off slowly toward it, by the tendency
of the inflammation to extend deeply into the subjacent tissues and into
the muscles and other structures, by the great tendency to death and
sloughing of portions of skin and of the structures beneath, by the
formation of pus at various different points throughout the diseased
parts witho