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VETERINARY MEDICAL SOCIETY. 
specimens which went far to make him suspect this part of 
Mr. Turner’s theory. From the inactive state in which the parts 
were placed by the suspension of their function, they became 
hard, unyielding; and inelastic; and the synovial membrane under¬ 
went sufficient injury to cause inflammation, from being squeezed 
between two hard bodies, the bone above and the bars beneath. 
Mr. Turner thought Mr. Perci vall’s speech most extraordinary. 
First, he differed from him as to the cause of the disease;—he then 
expressed his approbation of Mr. Goodwin’s opinion; and, after 
all, adopted his (Mr. Turner’s) own language in describing the 
origin of the disease, for he talked of the rigidity of the horny 
frog, and the bruising of the synovial membrane. This is the 
very essence of the thing. The principal disputed point however, 
appeared to be whether the navicular disease were connected with 
contraction. He imagined that the frog and bars, and that por¬ 
tion of the sole towards the heels becoming rigid and inflexible 
to all intents and purposes constituted contraction, and that with¬ 
out any apparent external contraction in the general form of the 
foot. If the coffin bone and bars were raised farther from the 
ground than their natural position, the cavity of the hoof was 
lessened, and this was contraction. The frog being confined, 
prevented the natural up and down motion of all the parts sur¬ 
rounding the navicular bone, and which being continued the 
synovial membrane could not but be injured. 
Mr. W. Percivall by contraction understood the lessening of 
the superficies of a thing, or the approximation of the two ends, 
or of the walls of a cavity. If this was not found, there could 
be no contraction. In the specimens on the table, there was 
neither shortening of the foot, nor narrowness of the heels, nor ele¬ 
vation of the frog; in fact, there was no contraction. As to the 
rigidity of the frog and bars, he did not mean to dispute this,— 
it seemed to be necessary to produce the disease. The point for 
consideration is the existence of the occult contraction of which 
Mr. Turner speaks. 
Mr. Goodwin .—The specimens on the table shew that occult 
contraction is not the invariable cause, and I do not believe that 
it is the usual cause of navicular disease. Here is the hoof of a 
horse that was lame three years without the slightest contraction. 
The horse to which this hoof belonged was fourteen years lame, 
and fit only for cart work, and was remarkable for the perfect 
form of his feet. The contents of the hoof were macerated out; 
it was then filled with plaister of Paris, and its shape accurately 
preserved. 
Mr. Turner .—But these were instances in which both feet 
were affected. The horse had not been induced to bear his 
