HORSESHOEING. 49 



gradually increase in width down to the middle, and thereafter 

 maintain that breadth to the lower border of the os pedis, where 

 they terminate in free, fleshy villi, which differ in no respect 

 from those of the fleshy sole. The number and length of the 

 fleshy leaves vary ; in a medium-sized foot there are about five 

 hundred, while in a large foot there may be as many as six 

 hundred. On the anterior surface of the os pedis the leaves are 

 thickest and longest; on the sides and quarters they gradually 

 decrease in length, while in the bar region they are the shortest 

 and gradually disappear near the anterior ends of the bars. 

 The width of the leaves decreases as they become shorter. Viewed 

 with the naked eye the leaves appear flat and smooth, but under 

 the microscope one can see on both sides of a fleshy leaf numer- 

 ous small, fleshy leaflets parallel to one another and extending 

 lengthwise with the larger leaf. The large ones are called piin- 

 cipal leaves, and the small ones are kno^vn as collateral leaves, 

 or simply as lea fiefs. 



The fleshy leaves (podophyllous tissue) secrete the horny 

 leaves (keraphyllous tissue) and serve to bind the homy wall 

 to the pododerm. The strength of this union is due largely 

 to the dovetailing of the horny leaves and their leaflets with 

 the fleshy leaves and their leaflets. 



4-. The ffeshy sole or velvety tissue of the sole (Fig. 29, h) 

 is that part of the pododerm which covers all the under sur- 

 face of the foot except the plantar cushion, the bar lamina^, and 

 the bar portion of the coronary band. It is sometimes slate- 

 colored or studded with black spots, but is usually dark red. 

 It is thickly set with villi, which are especially long and 

 strong * near its periphery. The fleshy sole covers the solar 

 plexus, or net-work of veins, and secretes the horny sole. 



5. The velvety tissue of the frog (Fig. 29, c) covers the 



* In order to see the length, thickness, and abundance of the villi 

 of the pododerm, place the foot deprived of its hoof in a clear glass 

 jar and cover it with waterj renewing the latter until it is no longer 

 tinged with blood. 

 4 



