HORSESHOEING. 



49 



by two fleshy leaves (Fig. 30). The keraphyllous layer and the 

 horn of the inmost part of the middle or protective layer are 

 always white, even in pigmented (colored) hoofs. 



Fig. 30. 



c c 



Cross-section of keraphyllous and podophyllous laminse (homy and fleshy leaves) : a, inmost 

 part of the solid wall ; the horn-tubes approach very close to the horny leaves ; 6, body of the 

 podophyllous membrane ; c, homy portion of a horn-leaf directly continuous vrith the middle 

 or principal layer of the wall ; d, a rudimentary horn-leaf that does not reach the body of the 

 podophyllous membrane ; c", cross-section of horny leaves from the sides of which branch 

 many secondary leaves (leaflets) composed of soft (young) hom-cells. These soft cellular 

 horn-leaflets dovetail with the podophyllous or fleshy leaflets ; d, podophyllous laminse ex- 

 tending from the body of the podophyllous membrane ; d', podophyllous laminse which have 

 branched in their course to the wall, and thus given rise to d, rudimentary horn-leaves ; d", 

 cross-section of podophyllous leaflets extending from the sides of the podophyllous leaves ; 

 each two such leaflets secrete a keraphyllous leaflet between them ; e, injected arterial vessels. 



The horn sole (Fig. 27, /, and Fig. 29, g) is secreted by the 

 velvety tissue of the sole. A sole from which the loose flakes 

 of old horn have been removed is about as thick as the wall. 

 It covers the under surface of the foot, and presents upon its 

 upper surface a convexity which exactly fits into the concavity 

 on the under surface of the os pedis. This upper surface is 

 thickly covered by a multitude of minute funnel-shaped open- 

 ings for the reception of the villi of the velvety tissue of the sole 

 (Fig. 31). The lower surface of the sole is more or less concave, 

 rough, uneven, and often covered by loose scales of dead horn. 

 Behind, the sole presents a triangular opening whose borders lie 



