738 



SOLIPEDA. 



evitably cause the destruction of living tissues, 

 becomes so diffused as to produce no incon- 

 venient results. 



The horny lamellae above alluded to, when 

 removed from the hoof, have little or no 

 elasticity when drawn in a longitudinal di- 

 rection ; but when drawn transversely, they 

 possess this quality in a very remarkable de- 

 gree, more especially in resisting pressure ap- 

 plied in a direction outwards and downwards, 

 to resist which, the arrangement of their fibres 

 is, on close examination, found to be particu- 

 larly adapted. 



The whole horny hoof, if unravelled by 

 maceration or long continued exposure, is 

 found to be essentially composed of longitu- 

 dinal corneous threads or hairs matted, and, as 

 it were, strongly glued together, a structure 

 preeminently adapted to combine all the re- 

 quirements of strength, elasticity, and tough- 



ness. 



As it approaches the quarters and heels, 

 the horny helmet encasing the foot diminishes 

 in its thickness as well as in height, affording, 

 by this means, a degree of pliancy, which here 

 becomes as necessary as firmness and unyield- 

 ing solidity were in the front of the organ ; 

 yet, even here, by the doubling in of the hoof 

 towards the sole, a strong horny margin is 

 left, which is admirably adapted to receive the 

 principal bearing of this part of the foot, and 

 to protect and defend the sole enclosed within 

 its curvature. 



Frog. The triangular chasm left by the 

 inflections of the wall towards the centre of 

 the foot, is filled up by a very remarkable 

 organ, named, in the language of farriery, the 

 " frog," either from some fancied gross resem- 

 blance which it bears to that animal, or, more 

 probably, by corruption, from the French 

 " fourche " or " fourchette," Anglice " fork," 

 applied to the same structure. By Latin 

 writers, it is generally known under a similar 

 appellation, " furca," and by the Greeks was 

 named " x^'Sora," from a similarity between 

 its shape and that of a swallow. 



This body, which externally has the ap- 

 pearance of a triangular mass of elastic horn, 

 may not be inaptly compared to an elastic 

 key-stone received into an elastic arch com- 

 municating in some cases, and admitting in all, 

 the springing movements of which such an 

 arch would be capable. Its bar, which, to- 

 wards the heels, is thin and broadly spread 

 out, possesses a considerable degree of flexi- 

 bility, which is gradually lost in approaching 

 the centre of the foot, where there is less 

 occasion for movement. 



The base of the frog lies between and con- 

 nects together the two posterior incurvations 

 of the hoof ; it then passes over and en- 

 ve'opes those parts, restraining their action. 

 The sides of the frog are united by applied 

 surfaces to the upper edge of the arch formed 

 by the sole, or more truly the bar formed 

 by the continuation of the wall. Its point 

 extends to or beyond the centre of the sole. 



The frog recedes from pressure in the na- 

 tural foot, by having its level within the level 



of the other parts of the under surface of the 

 foot, taking a third rate or degree of bearing 

 upon the ground : the wall first ; the bar next 

 projecting beyond it: its base also retires 

 further from pressure than the other parts of 

 it, and is protected by the projecting angles of 

 the horny or lower heel. 



On either side, the frog is bounded by deep 

 longitudinal excavations or channels, named 

 the commissures of the frog ; the bottom or 

 deepest part of these channels, forming the 

 line of un'on of the frog with the bar, a space 

 is thus afforded on either side of the frojj, 

 which, as an elastic body, would have been 

 useless without it; for in vain would elasticity 

 have been given to any part, unless sufficient 

 room was also given for its expansion. To- 

 wards the heels, these commissures are of 

 considerable width, and they are there arched 

 over by horny prolongation, from the base of 

 the frog, named the arch of the commissure. 

 The other extremity of the commissure grow- 

 ing, by degrees, shallower, is lost in the level 

 of the sole, before it approaches the arch of 

 the frog. 



Seen from without, the frog makes a bold 

 projecting appearance, as though it were a 

 solid body of horn ; and the smiths, deceived 

 by this appearance, entertain but indifferent 

 notions of its real structure, and use their 

 paring knives upon it much more freely than 

 its thickness warrants; for it is in reality 

 only an inverted arch of horn that is turned 

 downwards and reversed in respect to the 

 general arch formed by the sole and bar, so 

 that its real thickness in horn is by no means 

 so considerable as on a first view it would 

 appear to be. 



Examined from within that is to say, when 

 the foot has been drawn forth from the h oof 

 the frog presents an inverted triangular arch, 

 so intimately connected with the bar and sole, 

 that no one would suspect it of being a distinct 

 or divisible part, one uniform uninterrupted 

 surface being everywhere observable on this 

 inside : it may, however, be exhibited as a dis- 

 tinct inserted part by making a horizontal sec- 

 tion of the foot through the union of the bar 

 with the side of the frog, when the difference 

 of their structure and appeaiv.nce, and the line 

 of their applied surfaces become sufficiently 

 visible and distinct. A hoof exposed to the 

 weather will also be seen in its decav to se- 

 parate at this part first, and thus readily show 

 its distinctness from the rest of the hoof. 



In a perfect, well-formed foot, undistorted 

 by shoeing, Bracy Clark observes that " the 

 base of the frog occupies a certain division of 

 the general circle of the hoof, and that this 

 division is about a sixth part of the whole 

 circumference. By knowing this fact we are 

 not only led to entertain more just notions of 

 the form of the foot and the proportions of 

 its parts, but it affords us also an easy means 

 of forming a pretty accurate guess of what in- 

 jury or diminution the foot has sustained at 

 any period of the life of the horse without 

 previously seeing the original state of the 

 froji." 



