t may not prove efficacious, owing to the great
malignancy of the cancer and its tendency to recur. In such cases the
animal may be slaughtered, but the flesh should be used for food only after
inspection by a competent veterinarian.

CYSTS.

Cysts may be true or false tumors and consist of a capsule containing a
fluid or semisolid content. Among the most important cysts, which have been
briefly referred to in a previous table, the following are probably the
most noteworthy, owing to the frequency with which they are found in
bovines:

SOFTENING CYSTS.

Softening cysts, which result from the degenerative liquefaction of normal
or diseased tissues, especially of tumors of different kinds, followed by
the encapsulation of the fluid.

PARASITIC CYSTS.

Parasitic or foreign-body cysts, from the inflammatory reaction induced by
such parasites as the echinococcus (hydatid cyst) or by the presence of
various kinds of foreign bodies.

EXTRAVASATION CYSTS.

Extravasation cysts, caused by injuries which rupture blood vessels,
followed by an increase of fibrous tissue which forms a capsule about the
fluid. The hygromata in front of the knee in cattle, so-called tumor of the
knee, and serous cysts belong to this variety.

HYGROMATA, OR TUMORS OF THE KNEE.--These consist in the simplest form of a
collection of serous fluid mixed with fibrin within a distended bursa. The
walls surrounding the fluid become firm, smooth, and dense.

Outwardly the tumor appears fluctuating, though tense, while the skin which
covers it may be normal, denuded of hair, or covered with hard epidermal
scales, possibly half an inch in thickness, forming a hard, horny plate.
The cavity which contains the fluid may have the dimensions of a hen's egg,
an apple, or a child's head. Its walls are formed by the diseased secreting
membrane of the bursal sac, and are readily detachable from the subcutis of
the skin. Their internal surfaces are often uneven or supplied with
projections or tufted growths which support a fibrous network within the
tumor.

Tumors of the knee may also assume a granular type, as the result of
chronic inflammation or following operative or spontaneous evacuation of
pus from the part. They are either firmly connected with the skin or are
detachable from it, and when laid open disclose a whitish-red, porklike
tissue surrounding a central nucleus of pus, or a fistulous tract leading
to the outer surface. They are caused by