334 TRANSACTIONS AT THE ALFORT SCHOOL 
poses, likewise diminishes sensibly in its substance : a loss 
which would appear to be referable to defective nutrition, as 
well as to the desiccation of the tissues in general entering 
into the composition of the navicular sheath. It is imme- 
diately contiguous to the ulcerations that this thinning pro- 
cess is going on, where the cortical surface of the bone, being 
completely bared, exhibits the polish of ivory. Between 
these ulcerations, and beyond the central part where they 
are so numerous, we observe, across the thinner part of the 
enveloping tissue, small red lenticular spots, which exhibit 
their counterparts through the depth of the osseous tissue. 
These small spots, according to writers on this subject, are 
the first indications of ulceration. This is possible and 
admissible enough ; but it is difficult to confirm this induc- 
tion by post-mortem inspection, since the occasions of dis- 
secting animals dying with such disease on them in the 
incipient stages are not very frequent. 
The ulcerations upon the navicular bone serve, on occa- 
sions, as points of implantation for bundles of fibres, detached 
longitudinally, from the superior surface of the plantar apo- 
neurosis, in the manner of shreds from bark which one has 
just stripped off twigs of green wood. In these cases, the 
tendon of the perforans is divisible upon its internal sur- 
face, as it glides over the pulley-like one of the navicular, 
into several irregular needle-like shreds, of unequal size, 
which seem to insert themselves into some of the points 
where the bone is roughened and eroded by the ulcerations. 
The expanded tendon of the perforans becomes so attenuated 
that it is reduced to a thin membrane, which now and then 
breaks at its insertion into the navicular. The remarkable 
alteration taking place in this disease is atrophy of the tissues, 
showing itself by dry ulcerations of the bone, and arriving at 
such a height that the bone itself becomes sensibly reduced 
in volume, and thin to a degree to be on the point of 
breaking, and the aponeurosis to become absorbed. How 
comes it there should be here such a difference in the regular 
procedure of things ? Hitherto this has puzzled us. Be it as 
it may, it is clear that a disease presenting itself with such 
characters is superior, in the immense majority of cases, to 
every effort art can employ to restore the nutritive action to 
its normal rhythm, though neurotomy is the last resource the 
Veterinarian ought to have recourse to : not with any view of 
curing the disease ; but, at smallest, to palliate its effects, and 
render once again, for some months at least, useful, an animal 
who, but for such an operation, would be altogether unfit for 
anything. 
