d to
the owner, and his consent obtained for immediate destruction.

_Pathology_.--The pathological changes occurring in suppurative arthritis
we shall pass over briefly. It is almost sufficient, in fact, to say that
the whole of the joint becomes completely disorganized.

The synovial membrane becomes so tremendously thickened and injected as to
be scarcely recognisable as such, the thickening in the later stages
being due to large growths of granulation tissue which entirely alter the
appearance of the membrane as we know it normally. In the early stages
the contents of the joint are composed of thin pus and synovia. Later,
as destruction of the synovial membrane proceeds, the flow of synovia is
stopped, while the pus formation goes on until finally nothing but pus and
dead tissue products fill the cavity.

If the suppurative process has commenced from within, the pus that is
formed is, as a rule, thick and creamy, comparatively unstained, and free
from marked odour. If, on the other hand, air has gained access to the
joint, or the suppurative process has started from the materials introduced
by a foreign body, the joint contents are thin, blood-stained, and
stinking.

The inflammatory changes in the joint soon spread to the ligaments, and to
the soft structures in contact with them. This means that the ligaments
become infiltrated with inflammatory exudate, that the fibrous bundles
composing them become separated, and that the ligaments are weakened and
easily stretched. As a consequence, a certain amount of displacement or
dislocation of the bones is allowed.

In like manner the inflammatory changes keep spreading until we have the
periosteum next the ends of the bones affected. The periostitis thus set
up invariably takes the osteoplastic form, and as a result of this we have
growths of new bone in the near neighbourhood of the joint. It is in the
later stages of the disease--that is, when the pus has been evacuated and
reparative changes commenced--that this osteoplastic periostitis is most
marked, and it plays a large part in bringing about the condition of
anchylosis, which we shall afterwards describe.

Grave changes also occur in the articular cartilages. They quickly lose
their peculiar glistening polish, their semitransparency is lost, and the
natural tint of a pearl-like blue gives way to a dirty yellow. Later this
is followed by erosion of the cartilages at such points as they happen to
be in greates