REVIEW. 
151 
dilatation of the divisions of the hoof behind than this ? Is 
it not a phenomenon identical with what takes place in a bow, 
when its superficial fibres, split at the centre of their con¬ 
vexity, separate every time the bow is bent, and resume their 
former place whenever it is straightened ? This proof of the 
expansibility of the hoof, furnished us by daily observation, 
receives confirmation from Mr. Reeve’s ingenious researches. 
Notwithstanding Mr. Gloag’s opinions to the contrary, it appears 
to us that his experiments shew that the hoof at the moment of 
appui experiences dilatation, extremely nice of detection no 
doubt, yet still sufficient to receive and preserve the impressions 
of the points of the iron pins, which, before the foot was put 
down, simply touched the surface of the horn*. 
“ Lastly, we may adduce as proof of the expansibility of the 
hoof, the phenomena we are able of ourselves to elicit by subject¬ 
ing a fresh foot to the force of pression, applied so as to imitate 
that of the superincumbent weight upon the living foot. 
u Such experiments, with the measurements they afford us 
opportunities of taking, furnish clear evidence of the expansion 
of the foot, as well in its superior as in its inferior parts : also 
that the superior dilatation exceeds the inferior, whenever, under 
the operation of pression, the pasterns are directed backward, 
so as to throw the pressure upon the bulbous mass (the fatty 
frog) behind; whereas, the inferior dilatation becomes the 
greater whenever the small pastern is tilted perpendicularly 
upon the coffin-bone. The degree of expansion, as ascertained, 
as nearly as possible, by admeasurement, will, of course, vary 
under various and different circumstances; and experiments 
made with the view of determining this, seem to warrant us in 
coming to the conclusion, that the hoof of the horse is suscep¬ 
tible of an expansion, restrictive though it be, still of a real and 
demonstrable character. 
“ We do not bring forward here what is usually regarded as 
evidence of expansion, the shining and polished marks pre¬ 
sented by the foot-surfaces of old shoes , since such brightened 
places upon the shoe shew no more than the fact, that they 
have been opposed to the hoof, and are the result of collision 
with it. The proof of which is, that if a flat shoe be put on 
without being fitted out, its upper surface will exhibit polish to 
a much greater extent than in the other case, owing to the larger 
surfaces of contact; and if, in ordinary shoeing, the parts of the 
shoe towards the heels exhibit the broadest shining marks, such 
extension is ascribable to the circumstance of the bearing being 
broader at the parts where the wall makes its inflexions, as 
* For an explanation of this, see Mr. Reeve’s experiments in The Veterina¬ 
rian, vol. xxiii, p. 61 . 
