THE HORSE. 



33 



eluding those of the bars. They vary, 

 however, in number : I have reckoned up- 

 wards of 600. 



" Dimensions. — In length they decrease 

 from around the toe towards the sides and 

 heels in a corresponding ratio with the 

 wall ; those in front, the longest, being 

 rather more than two inches in extent ; the? 

 shortest, those at the heels, being rather less 

 than one inch. In breadth there is no vari- 

 ation : all measure alike, one-tenth of an 

 inch. 



" Organization. — The laminae are highly 

 organized, though they are not equally so 

 with either the sensitive sole or sensitive 

 frog; nor are they so red as those parts: 

 and the obvious explanation of this is, 

 that (over and above what is requisite for 

 their own nutrition) all the blood they have 

 occasion for is only that which is suffi- 

 cient for the secretion of the horny la- 

 minjE. 



" THE SENSITIVE SOLE. 



" The sensitive sole, or (as Sainbel calls 

 it) the fleshy sole, is the fibro-vascular sub- 

 stance covering the arched concave, or 

 ground surface, of the coffin-bone ; in fact, 

 is the part corresponding to the horny sole. 



" Structure. — The same kind of elastic 

 fibrous structure that sustains the laminae 

 is found constituting the groundwork of the 

 sensitive sole ; only that in the latter case it 

 is closer, denser, and firmer in its texture. 

 Upon this is spread a remarkably beautiful 

 venous network. And the whole is en- 

 veloped in an outer cuticular covering, 

 derived from the heels and frog, from which 

 are sent villous processes, loaded with the 

 points of arteries into the porosities of the 

 horny sole: not, however, perpendicularly 

 downward, but in an oblique direction — 

 downward and forward — the same in 

 which the horny fibres grow. 



" Connection. — Around the circumfer- 

 ence of the coffin-bone, the sensitive sole 

 is connected with the fibrous substance de- 

 scending from the wall, together with the 

 tapering, vanishing points of the laminae. 

 In the centre, it is united with the bars and 



frog. But its principal attachment consists 

 in its being firmly rooted into the sole of 

 the coffin-bone ; a connection that receives 

 considerable addition from the blood-vessels 

 issuing out of the substance of the bone. 



" Thickness. — The sensitive sole varies 

 in thickness at different places. On an 

 average, it may be said to measure one- 

 eighth of an inch in thickness. In the vi- 

 cinity of the frog, it is something less than 

 this. At the heels, it possesses double that 

 thickness. 



" Organization. — This is one of the 

 most vascular and sensitive parts in the 

 body. Independently of the much ad- 

 mired venous network expanded over the 

 fibrous substance of the sole, arteries enter 

 it issuing from the substance of the bone, 

 and penetrate its villi, w^hich, by taking this 

 course, elude all compression and obstruc- 

 tion : there are also others — the nutrient 

 arteries ; but these have an external origin, 

 from the inferior coronary artery. The 

 chief assemblage of arteries takes place 

 within the villi, upon the cuticular surface 

 — those issuing out of the interior of the 

 bone simply passing through (without ram- 

 ifying within) the fibrous substance : so 

 that, if the substance of the sole is laid 

 open by transverse section, th^ incised 

 edge, near the surface, exhibits a deep red 

 tint ; while the interior, nearer the bone, 

 has a pinkish or pale red aspect. 



" THE SENSITIVE FROG. 



" Under this head is included the cleft, 

 cuneiform body, projecting from the bottom 

 of the foot, together with the substance 

 continued from it and filling the interval 

 between the cartilages. Sainbel calls it 

 ' the fleshy frog.' 



" Division. — We distinguish, in the 

 sensitive as in the horny frog, an apex or 

 toe ; two heels, separated by the cleft ; and 

 a portion intermediate between these, which 

 is the body. 



" Situation and Connection. — The sensi- 

 tive frog occupies the posterior and central 

 parts of the bottom of the foot, forming in 

 the tread a firm and secure point d^appui. 



