88 VETERINARY LECTURES 



ence on the newly-secreted horn, and should never be destroyed by 

 the rasp. The internal portion of the wall is a leaf- like, or 

 laminated, structure, which dovetails into the sensitive laminae sur- 

 rounding the coffin bone. It has been estimated that there are 

 between 500 and 600 of these non-sensitive horny laminae and a like 

 number of sensitive ones, each being again studded with about 100 

 secondary ones, like the barbs of a feather, making the dovetail more 

 complete. These give a surface to the foot, estimated to be equiva- 

 lent to 8 square feet, or a total area for the 4 feet of 32 square feet. 



169. The Sole {Plate XL, No. 5, F) is the under or ground 

 portion of the hoof, and is slightly concave, filling up the space 

 between the bars (Plate XL, No. 5, D) and the ground surface of 

 the crust or wall. On the ground surface a white rim is seen, 

 called the 'white line,' which marks the union of the sole with the 

 wall (Plate XL, No. 5, E). The sole consists of thin plates of horny 

 material, which flake or fall off successively, when they have done 

 their work, at the ground surface. The internal surface presents a 

 sort of very fine honeycombed appearance, with little depressions, 

 into which dip the papillae of the sensitive sole, and by which the 

 horny matter is secreted, The sole is supposed to contain about 

 37 per cent, of moisture. 



170. The Frog" (Plate XL, No. 5, G) is the triangular elastic pad 

 of horn, containing about 43 per cent, of moisture, fitting into the 

 space between the bars. It runs to a point towards the toe, and at 

 the back forms the bulbs (Plate XL, No. 5, K) of the heels. The 

 deep cavities between the frog and the bars are called commissures 

 (Plate XL, No. 5, H) of the frog. Along the middle of the ground 

 surface runs the cleft (Plate XL, No. 5, i"), corresponding to an 

 elevation on the internal surface, which is called the frog-stay 

 (Plate XIL t No. 2, M), and is attached to the fatty frog or sensitive 

 cushion. 



171. The Sensitive Structures of the foot are : (1) The coronary 

 band ; (2) the sensitive lamina ; (3) the sensitive sole ; (4) the fatty frog ; 

 (5) tendons and ligaments; (6) bones and cartilages — all of which are 



