PAEING A.KD EASPIKG. 91 



The injuries wliicli result from tlie excessive use of the rasp, 

 are of a different and somewhat less dangerous character than 

 those iufiicted with the drawing knife. The hoof contains 

 within its horny substance a certain amomit of latent moisture. 

 It is this latent moisture which keeps the organ strong and 

 tough, and any agency productive of inordinate evaporation 

 from its surface (a small amount is constantly exhaling), tends 

 naturally to render it dry, unyielding, and brittle. To prevent 

 this, nature has so constituted the foot, that it secretes a 

 peculiar substance which is spread in abundance over the 

 external siu-face of the crust. This substance consists prin- 

 cipally of silex or flint ; it is in fact a coating of flint, which 

 dries and hardens, thus preventing undue evaporation as well 

 as protecting the hoof from the heat of the sun.* Man, 

 however, so clever and so wise withal, must imjprove upon 

 Nature and beautify her works, and his notion of doing this upon 

 the foot of the horse, is by paring and rasping the organ, which 

 for the time being perverts her ends and intentions. The 

 rasping which a hoof ought to undergo, is slight in comparison 

 ■with that which usually takes place. It should be rasped 

 immediately below where the nails issue from the horn, and at 

 the border of the foot resting upon the shoe. Easping 

 immediately under where the nails are clenched, allows of their 

 being more securely fixed. It is also necessary to the border 

 contiguous to the shoe, and to the toe to shorten it. In cases 

 also where the horn grows more rapidly at the toe than at the 

 heels and quarters, shortening the former by rasping, wiU 

 materially aid in deepening the latter. 



* We observe a similar arrangement on the stem of the sugar cane. By 

 bending a piece of cane, the experimenter may notice upon the bent surface, a 

 number of loosened particles of metallic looking matter. This is the siliceous 

 covering of the cane. Similar deposits may be observed upon the outer surface 

 of straw, and most of the dried gi-asses. 



