436 PLANTAR SYSTEM. 



sitive sole ; after the same process as that by which the horny 

 FROG is secreted from the vilh of the sensitive frog. 



In a state of health of the foot, the secretion of horn is un- 

 ceasingly going on. Disease or injury of the glandular parts may 

 diminish, or altgether suspend the process ; disease, under certain 

 other forms, appears also to have the effect of increasing it ; but 

 whether we have any artificial means of effecting this, seems 

 questionable. The wall grows from above downwards. If a 

 mark be made in any part of the wall, it will remain until it 

 grows down and becomes cut off below, at the inferior border ; 

 and by observations made on the gradual descent and disappear- 

 ance of these marks, calculations may be formed of the period of 

 tiuie required for the renewal or restoration of the wall. 



Properties of Hor?i. 



Horn is a tough, flexible, elastic substance, consisting of tubu- 

 lar fibres, more or less intimately connected together, taking the 

 direction from the surface of the body on which it grows. Its 

 property of toughness or resistance much depends on its con- 

 dition in regard to moisture; for if it is exposed to a degree 

 of heat sufficient to abstract much of its natural juice or imbibed 

 moisture, it loses its flexibility and toughness, and becomes brittle. 

 On the other hand, saturated with moisture, it is converted into 

 a soft and highly flexible substance, but at the same time becomes 

 weak and unresisting. This known effect aids us to account for 

 the flat-footedness of horses reared in low, fenny, or marshy situ- 

 ations ; the hoof being constantly in a state of saturation with 

 moisture, the wall and sole yield to the superincumbent burthen 

 of the body, and the latter grows flat (instead of remaining con- 

 cave or arched), and even in some instances bulges. If oily or 

 unctuous applications have any effect in softening the hoof, they 

 appear to do so by filling the crevices and interstices be- 

 tween the fibres on the surface, and in this manner checking or 

 suppressing evaporation. Horn takes a high and beautiful polish. 

 Although much inferior in transparency to tortoise-shell, it may be 

 worked up to bear so near a resemblance to it as to be often, in 

 manufactures, substituted for it, as in combs, &c. The hoof admits 

 of an elegant polish ; and in that altered and improved state has 

 been manufactured into articles no less useful than valuable and 

 ornamental* : even the hoofs of the living animal may, by being- 

 kept clean, and when dry rubbed with linseed oil, be numbered 

 among the ornamental beauties Nature has bestowed upon 

 quadrupeds. 



* The Eclipse hoof, presented by his IVlajctily at Ascot Races, as the 

 reward uf the best horse on the turf, forms a notable illustration of this. 



