78 THE PROTECTIVE STRUCTURES OF THE FOOT. 



are continuous, the result is to produce at the heel a strong 

 three-cornered mass of horn, from which the bar runs obliquely 

 downwards and forwards, in contact with the posterior part of 

 the corresjDonding limb of the frog. 



The bars are a continuation of the wall, which turns inward 

 at the angle just mentioned. They run forward on either side 

 of the frog, following its general direction, though, as they 

 gradually become continuous with the horny sole, they do not 

 actually reach the point of the frog. The bars are inclined to 

 the perpendicular, so that their upper borders approach more 

 nearly to the middle line of the foot than the low^er, which 

 are closer to the wall. In other words, tlie lower borders 

 are wider apart than the upper. Each bar, therefore, has one 

 surface turned towards the middle line of the hoof, and one 

 turned from it, the former being the lower or inner, the 

 latter the upper or outer (figs. 45 and 46, c). The upper sur- 

 face lies within the horny capsule and bears horny laminae. 

 The lower, on the other hand, is free, and is bounded on one 

 side by the furrow marginating the frog (lateral lacuna of the 

 frog) ; its upper part unites with the upper part of the corre- 

 sponding side of the frog (compare with the light-shaded portion 

 in fig. 47, a to a'). The upper border (fig. 48, c) is to be regarded 

 as a prolongation of the coronary groove, and is punctated ; 

 the lower border comports itself like the bearing surface of 

 other portions of the wall (figs. 45 and 46). 



The relations of the bars are often erroneously described. 

 Certain authors believe that they extend as distinct and well- 

 defined portions of the wall to the point of the frog, and 

 there come in contact. This, however, is certainly not the 

 ease, though it might appear so on superficial examination. 



Their real extent is at once seen by studying the inside of a 

 hoof after removal. As only those parts which exliibit laminae 

 can be regarded as wall, the presence of lamina may be taken 

 as showing exactly how far the bars extend. A study of 

 the lower sensitive surface, on the other hand, may easily lead 

 to errors, and for two reasons. Firstly, because the bars, like 

 every other part of the wall, grow in an oblique direction 

 downwards and forwards, but also towards the bearing surface 

 of the wall. Under these circumstances, they extend further 

 forward on the ground than on the upper surface of the sole. 



