THE HORSE'S FOOT. 321 



a manner as to distinctly preserve the canals. These canals 

 constitute the excrementation outlets of the hoof through which 

 mortifice or waste matter make their exit ; and in them may 

 also be found the vessels in which the horn is secreted. The 

 small vessels arising from the vascular and nervous membrane 

 beneath .the hoof, which is considered as a continuation of the 

 true skin, enter also into these canals. The nails of man corre- 

 spond to the hoof of the horse, inasmuch as they are formed of 

 a substance analogous. 



If we examine the nail under a microscope we will find that 

 it consists of hard, transparent, and somewhat elastic plates 

 which adhere to the vascular or nervous membrane of the 

 papillae. The latter are arranged in longitudinal and parallel 

 rows. The internal surface of the nail, like that of the hoof, is 

 soft, pulpy, and marked with longitudinal grooves and promi- 

 nences corresponding to the laminal found within the hoof. 

 A similar arrangement, possessing, however, exquisite sen- 

 sibility, is found on that portion of the finger covered by the 

 nail; and by the natural adaptation the connection between 

 them is sustained. The nails are also a continuation of the 

 true skin. 



The Sole is the plate at the bottom of the foot united to the 

 inner edge of the wall and the outer sides of the bars, and not 

 to the lower surfaces. Its usual thickness is about one-sixth of 

 an inch, but varying greatly in different horses ; it is thicker 

 where it runs back between the bars and the wall. It is 

 secreted in plates which can readily be separated with a knife. 

 The sole is considered to be more elastic than the wall or crust, 

 and is the medium of the sensitive faculty, through which — 

 together with its powers of elasticity — the percussion of the 

 foot against the ground is regulated. In shoeing this should 

 never be cut into, as by so doing it would weaken the foot. 



The Frog is still more elastic than either of the parts de- 

 scribed, and any unnecessary paring on the part of the shoer,is 

 to be deprecated. The natural function of the frog is that of 

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