ANATOMY OF THE FOOT. 17® 



paneled, there is a separation in the middle 

 which is continued to the heel. When the 

 frog receives the pressure of the horse's 

 weight, this separation is increased, and con- 

 sequently the frog becomes wider; and, as it is 

 connected with the heels of the crust, the same 

 effect must be produced upon them. 



As great part of the frog is placed behind 

 the coffin bone, all the intervening space be- 

 tween it and the back sinew being filled with 

 a fatty elastic substance, it forms another of 

 those curious springs which Nature has pro- 

 vided to "prevent concussion. 



When the froo; is in contact . with the 

 ground, it is evident, from its connection with 

 the heels of the crust, as we have be lore ob- 

 served, and with two cartilasces or elastic bo- 

 dies, which are covered in great measure by 

 the heels and quarters of the crust, and belong 

 to the internal foot, that it must tend to widen 

 or expand the heels ; and Uowever they may 

 be disposed tQ contract, by the foot being- 

 kept hot and dry, such contraction cannot 

 possibly take place while the frog bears on tne 

 ground, because it is then opposed by a vcvy 

 considerable part of the animai s wt^iu^it. 



Ir has been suppo;3cd by some, tnat the 



