442 PLANTAR SYSTEM. 



about 500 ; not including tliose of the bars. They vary, how- 

 ever, in number : I have reckoned upwards 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 variation : 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 sufficient for the secretion of the horny laminse. 



The Sensitive Sole. 



The sensitive sole, or (as Sainbel calls it) the fleshy sole, is the 

 fibro-vascular substance covering the arched concave, or ground 

 surface, of the coffin-bone : in fact, is the part corresponding to 

 the horny sole. 



Strncivre. — 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 net-work. And the whole is enveloped 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. 



Connexion. — Around the circumference of the coffin-bone, the 

 sensitive sole is connected with the fibrous substance descending 

 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 connexion that receives con- 

 siderable addition from the bloodvessels issuing out of the sub- 

 stance 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 vicinity of the frog, it is something 

 less than this. At the heels, it possesses double that thick- 

 ness. 



Organization. — This is one of the most vascular and sensitive 

 pails in the body. Independently of the much adiuiicd venous 



