DISEASES OF THE JOINTS 427 
commences, it is good treatment to smartly blister the whole 
of the region of the coronet, the pastern, and the wound 
itself with a mixed blister of cantharides and biniodide of 
mercury, repeated at intervals of a fortnight. This prevents 
to some extent further infection of the wound, and assists 
also in promoting the changes that tend to anchylosis. 
(d) ANcHYLOsIS. 
The word anchylosis signifies the stiffening of a joint. 
When one has read the serious changes occurring within 
the joint in the more serious forms of arthritis, it is easy to 
understand how it comes about. In suppurative arthritis, 
for instance, we have the synovial membrane destroyed, the 
articular cartilages partly or wholly obliterated, and the 
former boundaries of the joint entirely lost. If the animal 
lives, nature is bound to make repair of a sort. The synovial 
membrane and the articular cartilages utterly destroyed, as 
we have described, cannot again be replaced. Nature can 
only build again from such materials as are left to her. In 
this case the material is bone. 
It must be remembered, however, that often the bone 
has been so diseased that spots of necrosis or caries within 
it are bound to remain unless moved by operative inter- 
ference. Such diseased portions, when dealing with the 
foot, are beyond reach of the surgeon’s knife, and we have 
no alternative but to allow them to remain. We get, 
therefore, in many cases, a condition of rarefactive ostitis 
occurring side by side with a slowly progressive caries 
within the bone, while outside is occurring an osteoplastic 
periostitis. The concurrence of these conditions leads in 
time to great increase in size of the parts, together with 
increasing anchylosis and deformity. 
C. NAVICULAR DISEASE. 
Definition.—Chronic inflammatory changes occurring in 
connection with the navicular bursa, affecting variously 
the bursa itself, the perforans tendon, or the navicular 
