HOESE-SHOEIXG. 133 



it is almost impossible to disunite without tearing them. The inner 

 face of the lower margin is united in a solid body to the horny sole 

 through the medium o; a narrow band of soft, light-colored horn, 

 situated between the two, and which we may call the " white line," 

 or " zone." 



The outer surface of the wall is generally smooth and shining in 

 the natural healthy state. 



The dimensions of the wall vary in different situations ; in front 

 it is deepest and thickest, but towards the quarters and heels it 

 diminishes in height and becomes thinner ; at its angles of inflection 

 — the points of the heels — it is strong. Its structure is fibrous ; the 

 fibres pass directly parallel to each other from the coronet to the 

 ground, each fibre being moulded on, as it is secreted by, one of the 

 minute tufts of blood-vessels lodged in the cavity of the coronet. 

 Microscopically, the wall is composed of minute cells, closely com- 

 pressed, and arranged vertically around each fibre, and horizontally 

 between the fibres. A point of much practical interest is to be 

 found in the fact that the fibres on the surface or outside of the wall, 

 are very dense, close, and hard — so dense, indeed, that the wall of an 

 unmutilated hoof looks like whalebone; but toward the inner surface 

 they become softer, move spongy, and easily cut. 



The Horny Sole is contained within the lower margin of the wall, 

 and is a concave plate covering the lower face of the pedal bone. In 

 structure it is fibrous like the wall, the fibres passing in the same 

 direction, and formed in the same manner by the tufts of vessels 

 projected from the membrane which immediately covers the bone. 

 These tufts penetrate the horn fibres to some depth, and, as in the 

 wall, maintain them in a moist, supple condition, such as best fits 

 them for their office. 



The sole is thickest around its outer border, where it joins the wall ; 

 thinnest in the centre, where it is most concave. A notable pecu- 



