80 WEST OF ENGLAND VETERINARY MEDICAL ASSOCIATION. 
itself. Let a cartilage cell undergo this granular degeneration, and 
the granules by accumulation and multiplication form a cavity in 
the hyaline matrix ; then let this cavity burst on the surface of the 
cartilage into the joint, and an excavation which can be seen by the 
naked eye is at once visible, and a so-called ulcer is produced. In 
an early stage of disease, this granular degeneration may only be 
detected by a microscopical examination. Yet in that early stage 
the microscope will always detect a spot of degenerative change 
taking place in that part of the tendon which has been in opposition 
with the ulcerative spot of the cartilage. Where the degenerative 
change has taken place in the bone, cartilage and tendon, yellowish 
plastic matter is often thrown out, which unites that portion of 
the tendon which has undergone the degenerative change with the 
diseased structure of the cartilage and bone ; in some cases only a 
few of the ulcerated fibres become attached to the ulcerated surface 
of the bone ; in other cases the entire articular surface of the bone 
and tendon become firmly adhered, producing an anchylosed joint, 
after which the pain is much lessened, but the poor animal goes in 
a very stilty manner, and not fit to go beyond a walking pace. In 
other cases the ligaments of the navicular bone, and the tendon, 
become ossified to the coffin-bone, also forming an anchylosed 
joint. In some cases the degenerative change goes on in the tendon 
(without the plastic process being set up) until there is not one 
half of the articulating part of it left, yet it seldom becomes rup- 
tured unless the nerves are divided. By the specimens it will be 
seen that nature is capable of repairing almost any amount of 
disease of the internal structure of the bone. 
As soon as the inflammation is entirely subdued, the vessels take 
on healthy action and begin to repair the diseased structure by an 
effusion of lowly organised lymph, which gradually becomes con- 
verted into bone of a porcelaneous character. This process of 
repair is well represented in every stage, both in the wet and dry 
specimens. 
Some of them have almost entirely undergone the porcelaneous 
process of repair, and appear to have performed the ordinary func- 
tions of the bone as well as before the disease occurred. Such 
favorable results can only occur in cases where the articulatory 
surface of the bone and cartilage have not taken on the diseased 
process sufficiently to produce an ulcer. Cartilage when diseased 
has not the power of regeneration ; the small spicula on the articu- 
latory surface of the cartilage is the result of the reparative process 
of the bone . 1 
There are a few specimens of fractured navicular bones, but 
they mostly belonged to horses which had undergone the operation 
of neurotomy. 
Treatment . — First endeavour to ascertain the history of the case, 
1 [It is only just to the professors of the schools that we should state 
that for many years past no such teaching as Mr. Broad alludes to has 
found a place in their lectures. It would thus appear that Mr. Broad is 
entirely misinformed respecting the views which are held by the profession in 
general of the pathology of navicular disease.] 
