24 
W. BRYPEN 
often found without navicular disease,” but “ navicular dis¬ 
ease ” never without “ contraction,” and within certain limits, 
always the same kind of “ contraction,” too. One may claim 
that the hoof must be pared ; the other, the opposite ; and 
that “ adaptability ” is or is not “ contraction ” might also be 
a contention, but will not get us out of the old ruts. * 
At the foot of page 335 Prof. Williams again informs us 
that “ During the past five years, I [Prof. W.] have made 
numerous post-mortem examinations of ‘ navicular disease,’ 
and am convinced that strain or laceration of the tendon is 
never a primary condition, and that the disease commences 
as an inflammation of the cancellated structures of the navi¬ 
cular bone, or of the cartilage upon its inferior surface.” Im¬ 
possible ! there is a history, and slow, gradual changes in the 
hoof and soft structures within it and covering the bone, 
without which it would not be “ navicular disease.” 
Inflammation of the cancellated structures, and of the in¬ 
ferior part of the cartilage, can only be present as the result 
of an accident, never at the beginning of true navicular dis¬ 
ease, which is a slow, gradual process when not complicated ; 
the bone degeneration is always the result of slow starvation 
of the structures within the bone. The tissues surrounding 
the bone become disturbed, perhaps congested, by the pres¬ 
sure or interference of the hoof, especially the sole and bars. 
This extends to, and affects the membrane covering the bone 
and lining the foramen, its functions are perverted, the ele¬ 
ments intended to nourish the bones are refused admission or 
diverted ; a process of necrosis , rather than caries, gradually 
follows ; small particles of the rejected or arrested bone ele¬ 
ments may then be transplanted or deposited on the exterior 
of the navicular bone, very much as in the degeneration of 
the cancellated structure in true bone spavin. 
It is said on page 342 that “ contraction of the foot always 
succeeds navicular disease ;” with equal truth it can be said that 
contraction of the hoof always precedes it. For it always does 
both if the disease continues ; at first, as an exciting cause ; after¬ 
wards, as a concurrent affection or process. For example: If a 
strong, robust, symmetrical, well-developed horse receives a 
