FORM AND ACTION OF THE FOOT. 15 



■crack, the irritation of the laminae causes excessive 

 •secretion, and a horn tumor results. The sensitive 

 laminae, then, fulfil two functions; they offer a firm con- 

 necting medium for the wall, and they secrete horn. 

 By the cruel experiment of removing the horny sole 

 and frog of a living horse and then forcing him to stand 

 •on the maimed foot on a level surface, it has been shown 

 that the laminae are capable of alone supporting the 

 weight of the animal. It has been argued from this that 

 the laminae always siipport the weight, and that the 

 horse's foot may be described as being slung by the 

 connecting laminae. Tliis is not true. The frog and 

 sole help to support weight, and the hoof acts as one 

 continuous whole, each part taking its direct and pro- 

 portionate share of the weight j^laced upon the foot. 

 ' The sensitive laminae are not elastic, they are unyielding, 

 ■ and, therefore, allow no downward yielding which would 

 impose excessive pressure on the sole. 



Tkh Coronary Band. (See Fig. 11.) The sensitive 

 laminae do not cover the whole of the upright portions of 

 the sensitive foot. There is between their upper extre- 

 mity and the line which separates the skin from the 

 sensitive foot, a convex band which runs round the 

 upper border of the foot, and is turned downwards and 

 inwards at the heels. This is called the coronary band, 

 and corresponds to the groove which we noticed on the 

 inner side of the upper border of the wall. On its sur- 

 face are innumerable small projections or papillae which, 

 in the living animal, fit into the openings on the groove 

 of the wall. From each of these papillae grows a horn 

 fibre, and from the surface between tliem is formed a 

 softer horny matter — the two products forming together 

 the substance of 'the wall. The coronary band is, then, 

 an important structure, being the source from whence 

 the wall is produced. Upon the healthy condition of 

 "this band depends the soundness of the wall, and any 

 interference with its integrity must lead to defects or 

 ^deformities in the wall. 



The Sensitive Sole (Fig. 12) is that portion of the 



