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the weaker of the two. The relative strength of the inner and 

 outer quarters have an obvious relation to their capacities for 

 resisting lateral, rather than those of sustaining vertical pressure. 

 These have been so fully discussed elsewhere, that I need not 

 extend their discussion further here. I deem it to have been 

 conclusively shown that contraction is primarily, and expan- 

 sion secondarily concerned in the production of fissures in the 

 various parts of the hoof, and that those who assert to the 

 contrary are not yet sufficiently instructed in, or have not fully 

 investigated the economy of the foot of the horse. 



THE QUARTER BEFORE— THE TOE BEHIND. 



Fissures in the quarters of the hind feet are very rare ; the 

 toe is the most frequent seat of this lesion. The motive forces 

 are chiefly concentrated in the toe of the hind foot; conse- 

 quently this part is subjected to greater strain than the toe of 

 the fore foot where these conditions exist in a much less degree, 

 and hence the greater frequency of toe-fissures behind than 

 before. A powerfully predisposing cause in all cases is a brittle 

 and unyielding condition of the horny wall. 



THE CAUSE— PAR EXCELLENCE. 



The proximate, exciting cause, in all cases is, par excellence 

 a morbid contraction of the hoof at points that obstruct the 

 functional expansion and contraction of the quarters, and 

 causes a morbid expansion of parts that are not designed to 

 expand, except in a very minor degree. 



WHAT TO DO, AND WHAT NOT TO DO. 



A few further observations may supplement the treatment 

 already indicated. 



A very severe crack in the toe or quarter may require a rivet 

 or a nail to keep it sufficiently close while growing down ; al- 

 though of hundreds of such cases, I have never met with but 

 one that required it during the last five years. 

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