24 



ANATOMY AND PHYSIOLOGY OF 



" Situation and Connection. — It fills up 

 the interspaces between the outer and inner 

 walls (or bars) of the crust. I differ in 

 opinion from those who describe it to sur- 

 round the toe of the frog. I hold its circum- 

 ferent support and connection to be the wall 

 of the hoof, to wliich it is firmly cemented 

 by an interstitial horny matter, filling the 

 crevices between the laminae. 



" Figure. — The circumferent outline of 

 the sole measures about two-thirds of a cir- 

 cle, the remaining third being omitted to 

 form a triangular-shaped hiatus or opening 

 for the reception of the frog and bars. This 

 circular form, however, is by no means true, 

 or even invariably the same, in its dimen- 

 sions. Generally, the longitudinal exceeds 

 the transverse diameter. Its greatest diam- 

 eter is shown by a line extended from either 

 heel across its middle to the opposite point 

 of the toe. 



" Arch. — Commonly, the sole presents 

 an arch of more or less concavity inferiorly, 

 and convexity superiorly. But it is not a 

 regular or uniform arch, being one that 

 rather waves or undulates, so as to bear a 

 comparison, made of it by Mr. Clark, ' to 

 the mouth of a bell extremely extended or 

 flattened.' Like that of the bell, the arch 

 is highest in the middle, from which it 

 slopes, laterally, down to a flat, subsequently 

 to rise again around its border, in order to 

 present a dilated surface for attachment 

 towards the w^all. There is, however, vast 

 variety in the degree of arch of the sole: in 

 some feet it is of surprising depth ; in 

 others, the arch is converted into a flattened 

 surface ; and yet both seem to perform 

 equally well. In the hind feet the sole is 

 generally more arched than in the fore, and 

 approaches in figure nearer to the oval than 

 the circle. 



'■'■ Division. — In the sole we distinguish 

 an anterior part or toe; a middle or central 

 part ; two points or heels ; and two surfaces. 

 These divisions are not very well defined : 

 but they prove serviceable in aid of our de- 

 scriptions. The toe of the sole is the part 

 encircled by the toe of the wall, against 

 which it abuts, and to which it is intimately 



united by horny matter, the two together 

 forming a stout bulwark of defence to those 

 parts of the internal foot included between 

 them. The points or heels are the two pos- 

 terior salient angles received into the angu- 

 lar intervals between the outer and inner 

 walls or bars. Although naturally the 

 least exposed, these are the parts most sub- 

 ject to injury or pressure from the shoe, 

 being the seat of that disease mistakenly 

 called corn. The middle or centre of the 

 sole is the portion more immediately sur- 

 rounding the fore parts of the frog, and 

 would (were the sole a regular arch) be the 

 most elevated part ; but, in general, we find 

 the sole flattened hereabouts; the highest 

 parts of the arch being the angles alongside 

 of the bars ; the lowermost, those around 

 the toe. 



" Surfaces. — Of the surfaces, the supe- 

 rior (as was mentioned before) is unevenly 

 convex ; the inferior, correspondently con- 

 cave. The former is everywhere pitted, 

 particularly about the heels, with numerous 

 circular pores, running in an oblique direc- 

 tion, the marks of which remain evident 

 upon the inferior surface hkewise. These 

 pores are the impressions made in the soft 

 horn by the villi of the sensitive sole, from 

 whose orifices the horny matter is produced. 

 They also form the bond of union between 

 the horny and the sensitive soles : which is 

 of a nature so strong and resisting, that it 

 requires the whole strength of a man's arm 

 to effect their separation — an operation of 

 a cruel description that was wont to be 

 practised in times past, under the fallacious 

 notion that ' drawing the sole ' was extir- 

 pating the malady. 



" Thickness. — The natural thickness of 

 the sole may be estimated at about one- 

 sixth of an inch. There will be found, 

 however, variations from this standard in 

 difi'erent horses ; and it will also very much 

 depend on the part selected for measure- 

 ment. The portion of the sole most ele- 

 vated from the ground — that w^hich forms 

 a union with the bars — is nearly double 

 the thickness of the central or circumferent 

 parts ; and next to this, in substance, comes 



