27 



sity and its great elasticity admirably fitting it for this office; 

 and it acts as a covering or protection to the wall at its upper 

 part, where this is only in process of formation, and has not 

 sufficient resistance to withstand the effects of exposure to the 

 weather. The greatest thickness and density of the band cor- 

 responds to the portion of the wall in which the villi ox vascular 

 tufts are lodged, and here the horn is soft, delicate, and readily 

 acted upon in an injurious manner, by external influences." 



Elsewhere he writes of its uses, and abuses : 



" The thin, semi-translucent horn that extends in a somewhat 

 wide, whitish-colored band, around the upper band of the foot, 

 is chiefly intended by Nature, I think, to protect the fibres of 

 the wall from the effects of external physical influences, such as 

 heat and dryness, while they are being secreted, or so immature 

 as to be incapable of resisting these influences ; for it will be 

 remembered that the wall is formed at the coronet, and this 

 covering guarantees, not only the integrity of the newly-made 

 horn-tubes, but also maintains the secreting vessels that enter 

 them, in a healthy condition, and competent to supply fresh 

 material for wear. The destruction of this band, and the rasp- 

 ing of the fibres beneath it, is detrimental to the healthy secre- 

 tion of the wall fibres, and leads to the same result that paring 

 the sole was shown to do: shrinking of the horn tubes con- 

 taining the tufts of vessels, wasting of these, a diminished 

 supply of horny material in* consequence, and a thin brittle 

 wall that scarcely appears to grow down at all, in depth or 

 thickness, and barely allows a shoe to be attached to it. Sand- 

 crack and other diseased conditions of this part of the hoof are 

 mainly due to this cause." To all of which I yield an unqual- 

 ified assent, excepting the last clause. Ascribing as I do the 

 chief proximate cause of quarter-crack to contraction of the 

 lower part of the quarter, and outward pressure upon the 

 upper, I am willing only to accept brittleness of hoof, etc., as 

 predisposing or secondary causes. 



