90 
REVIEW. 
superincumbent weight produces no expansion beyond this. 
For, no sooner does this pressure come to exert its operation on 
parts behind the central line of the quarters, and begin to affect 
the posterior parts of the hoof, acting still in the direction of the 
same incline of the bony column below, than, instead of being a 
dilating force, it becomes a maintaining (contractive,) one. And 
the manner in which M. Perrier explains this is as follows :— 
He regards the wall of the hoof as naturally oblique, as it 
advances from the heels, from above downwards and from, 
without inwards, the inclination from above downwards and 
from behind forwards being on a level with the angle of in¬ 
flection. This being the case, whenever weight comes to exert 
pression upon the interior of this part of the hoof, as a necessary 
consequence, while the superior part of the wall is forced from 
within outward by it, the inferior part is constricted ( concentre ) 
from without inwards; the same as a dilating force operating on 
the upper border of a cylinder tends to contract the lower 
border of it. 
“ In this constriction below, the wall carries the sole back 
towards the concavity of the coffin-bone, causing the heels of 
the one to approximate more exactly within those of the other, 
whereby is brought about a sort of locking (enclavement) of 
the branches of the sole between the alse of the coffin-bone, 
adding still farther to the maintaining (contentive) action. 
“ So that, according to M. Perrier, the foot enjoys the double 
property of dilatation and contraction ; and it is the weight of 
the body which puts this two-fold property into action : the di¬ 
lating force operating from the toe as far as the centre of the 
quarters, the maintaining (contentive) force from the same 
centre as far back as the extremity of the heels.” 
This opposite mechanical movement of the hoof M. Perrier 
represents as an admirable provision against the dilatation 
the foot enjoys being in excess or having existence in parts of 
the organ which, from their bifurcate character, call for an action 
of an opposite kind. The theory, M. Bouley thinks, is, to sav 
the least of it, ingenious, but asks “is it founded in fact?” 
He does not believe it is ; and we perfectly agree with him. 
The Experiments of Mr. Gloag touching elasticity, 
combatted by experiments made by Mr. Reeve on the same 
point, as detailed in vol. xxii and xxiii of The Veterinarian, 
come next under notice ; both of which, being within the recent 
recollection of our readers, we shall pass over in silence, 
