under surface
of the belly. We find them also with effusions of the liquid parts of
the blood into the lymph spaces of the posterior extremities and organs
of the pelvic cavity.

Tumors or other mechanical obstructions, by pressing on the veins,
retard the flow of blood and cause it to back up in distal parts of the
body causing passive congestion.

The alterations of passive congestion, as in active congestion, consist
of an increased quantity of blood in the vessels and an exudation of
its fluid into the tissues surrounding them, but in passive congestion
we have a dark, thick blood which has lost its oxygen, instead of the
rich, combustible blood rich in oxygen which is found in active
congestion.

The termination of congestion is by resolution or inflammation. In the
first case, the choked-up blood vessels find an outlet for the excessive
quantity of blood and are relieved; the transuded serum or fluid of the
blood is reabsorbed, and the part returns almost to its normal
condition, with, however, a tendency to weakness predisposing to future
trouble of the same kind. In the other case further alterations take
place, and we have inflammation.

INFLAMMATION.

(Plates I and II.)

Inflammation is a hypernutrition of a tissue. It is described by Dr.
Agnew, the surgeon, as "a double-edged sword, cutting either way for
good or for evil." The increased nutrition may be moderate and cause a
growth of new tissue, a simple increase of quantity at first; or it may
produce a new growth differing in quality; or it may be so great that,
like luxuriant, overgrown weeds, the elements die from their very haste
of growth, and we have immediate destruction of the part. According to
the rapidity and intensity of the process of structural changes which
takes place in an inflamed tissue, inflammation is described as acute or
chronic, with a vast number of intermediate forms. When the phenomena
are marked it is termed sthenic; when less distinct, as the result of a
broken-down and feeble constitution in the animal, it is called
asthenic. Certain inflammations are specific, as in strangles, the
horsepox, glanders, etc., where a characteristic or specific cause or
condition is added to the origin, character of phenomena, or alterations
which result from an ordinary inflammation. An inflammation may be
circumscribed or limited, as in the abscess on the neck caused by the
pressure of a collar, in pneumonia, in glanders, in the small