ives, 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 interference. 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 bone, and characterized by changes in the form
of the hoof and persisting lameness. The disease is commonly noticed
in thoroughbreds or in horses of the lighter breeds, and is but seldom
observed in heavy cart animals. Usually it is met with in one or both
fore-feet. Although of extremely rare occurrence, it has been noticed in
the hind.

_History_.--To English veterinarians appears to belong the credit of
discovering navicular disease. As early as 1752 we find one, Jeremiah
Bridges, in 'No Foot, No Horse,' drawing attention to 'coffin-joint
lameness,' and advocating for its treatment setoning of the frog. It
appears, too, that Moorcroft, prior to his departure for India in 1808, was
acquainted with what was then known as coffin-joint[A] lameness, having
drawn attention to it in 1804 in a letter to Sir Edward Codrington.[B] In
1819 Moorcroft made it even plainer still that he was fully acquainted with
what we now know as navicular disease. This we learn from a letter written
by him to Sewell, in which he laid claim to being the originator of
neurectomy. In this letter he says:

[Footnote A: The coffin-joint at this time included the navicular bursa.]

[Footnote B: Percival's 'Hippopathology,' vol. iv., p. 132.]

'On dissecting feet affected with these lamenesses, the flexor tendon was
now and then obser