PLANTAR SYSTKM. 4^3 



net-vvovk expanded over the fibrous substance of the sole, arteries 

 enter it issuing froui the substance of the bone, and penetrate its 

 villi, which, by taking this course, elude all compression and ob- 

 struction : 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 ramifying within) the fibrous 

 substance : so that, if the substance of the sole is laid open by 

 transverse section, the 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, pro- 

 jecting from the bottom of the foot, together with the substance 

 continued from it and filling the interval between the cartilages. 

 Sainbel call it " the fleshy frog." 



Division. — We distinguish, in the sensitive as in the horny 

 frog, an opex or toe ; two heels, separated by the cleft ; and a 

 portion intermediate between these, which is the bodi/. 



Situation and Connexion. — The sensitive frog occupies the 

 posterior and central parts of the bottom of the foot, forming in 

 the tread a firm and secure point d'appui. Being in the hoofless 

 foot equally prominent with the projecting edge of the coffin- 

 bone, one might be led to infer that the horny frog should take 

 the same line of bearing with the crust. The frog, altogether, 

 is lodged in a capacious irregular space, bounded superiorly by 

 the tendo-perforans and common skin, laterally by the cartilages, 

 and inferiorly by the horny frog: with all which parts it has con- 

 nexions ; besides being continuous with the sensitive bars and 

 sole, and at the heels with the coronary substance. On its sides 

 are two shallow ill-defined hollows, corresponding to the com- 

 missures of the horny frog, into which are received the horny 

 prominences opposed to them. 



Structure. — Entering into the composition of this body we 

 distinguish four parts: — An exterior or cuticular covering; a 

 congeries, or network of bloodvessels ; a fibro-cartilaginous texture ; 

 and an elastic interstitial matter. 



The exterior or cuticular covering invests the prominent bul- 

 bous portion of the frog, and also gives a lining to the cleft. 

 Superiorly, it is continuous with the skin descending upon the 

 heels; anteriorly, with the cuticular covering of the coronet; in- 

 teriorly, with that of the sole. Numerous villous processes sprout 

 from its surface, and enter the porosities in the interior of the 



