80 ARTISTIC HORSE- SHOEING. 



(with the exception of the portion of the wall covered with 

 the horny leaves) by multitudes of minute processes named 

 villi, which are not only concerned in the growth of the 

 horn-fibres, acting- as moulds for them, and endowing the 

 hoof with that degree of lightness, elasticity, and tough- 

 ness, which are so necessary to its efficiency, but also make 

 this insensitive case a most useful organ of touch. 



The growth of the horn takes place by the deposition 

 of new material from the secreting surface ; this deposi- 

 tion is effected at the commencement or root of the fibres ; 

 where the horn is yet soft, and its incessant operation 

 causes these fibres to be mechanically extended or pushed 

 downward tow^ard the ground in a mass. Once formed 

 they are submitted to no other change than that of becom- 

 ing denser, harder, less elastic, and drier, as they recede 

 farther from the surface from which they originated. 



So regulated is this growth, generally, in every part of 

 the hoof, that it would appear that the secreting mem- 

 brane is endowed with an equal activity throughout. 



But, though this equality in the amount of horn secreted 

 over so wide a sui^face is an undoubted fact, yet it must 

 not be forgotten that, under the influence of certain condi- 

 tions, the growth or descent of the corneous material may 

 be effected in an irregular manner, either through a partic- 

 ular portion of the secretory apparatus assuming a more 

 energetic activity, or being* hindered more or less in its 

 function. 



For instance, the way in which the foot is planted on the 

 ground has a most marked influence, not only on the amount 

 of horn secreted, but also on that subjected to wear. 



