198 THE STRUCTURE OF THE HORSE. 



of the human nail, though differing in its much 

 greater thickness and in the sides being not only 

 greatly prolonged backwards, but also sharply bent 

 inwards and forwards, forming the " bars " (Fig. 26, 

 5 and 6). The upper edge of the wall is hollowed to 

 fit on to the coronary cushion. The inner surface 

 is longitudinally furrowed by deep and complex 

 grooves, which exactly correspond to the delicate 

 lamellae and laminellae of the " podophyllous tissue." 

 The new hoof continually grows from the coronary 

 cushion above, and slides down over the lamellae of 

 the derm, receiving from them upon its inner side a 

 certain amount of addition to its thickness in the 

 form of soft epidermic cells, which afterwards harden 

 and become incorporated in the general mass. The 

 external surface of the wall when in a natural con- 

 dition is smooth and shining, and appears to be made 

 up of fine, closely arranged, parallel fibers, passing 

 in a straight hue from the upper to the lower mar- 

 gin. There are also not unfrequently transverse 

 grooves or rings, indicating varying conditions of 

 the matrix at the time of growth, especially marked 

 in certain abnormal states of health. 



The different regions of the wall have received 

 technical names useful for descriptive purposes. The 

 front part is called the " toe " (Fig. 26, 2, 3) ; the two 

 sides, the outer and inner " quarters " (1,2, and 4, 3) ; 



