76 THE PROTECTIVE STRUCTURES OF THE FOOT. 



toe to h, and figs. 45 and 46 from a to a) extends on either side 

 of the middle line for a distance equal to about one-tenth of 

 the entire circumference of the foot ; it, therefore, comprises 

 about one-fifth of the whole extent of the wall. 



(b) The quarter (fig. 44, h to c, and ligs. 45 and 46, a to h) ex- 

 tends backwards from tlie boundary of the toe, on either side, 

 for a like distance. 



(c) The heel (fig. 44, c, e, and tigs. 44 and 45, h, d) includes 

 the parts between tlie boundary of the quarter and the inflec- 

 tion of the ]^ars. 



{d) The inflection of the bars (figs. 45 and 46, d, 47, ^^ &) is the 

 spot where the wall turns in a forward direction, forming an angle. 



{e) The continuation of the wall in a forward direction 

 between the sole and horny frog is named the bars (figs. 45 

 and 46, c, and fig. 47, c). 



The direction, length, and thickness of the wall at the toe, 

 quarters, and heels respectively, vary not only in the fore and hind 

 feet of the same horse, but even in the two halves of the same hoof. 



In the normal lioof the wall of the toe has the s^reatest in- 

 clination to the oround surface, forrain**- in fore-feet an an^ie of 

 45° to 50°, in hind-feet of 50° to 55°. This inclination is less 

 at the quarters and heels, where the wall becomes nearly perpen- 

 dicular. It may, indeed, surpass a right angle, the wall in such 

 cases running from above downwards and inwards. The angle 

 between the quarter and the ground surface is always greater in 

 the outer portion of the wall, the reason being that the outer wall 

 describes a larger circle than the inner (compare figs. 45 and 46). 



The fact that the wall slopes outwards renders it evident 

 that the circumference of the foot must be lijreater at the bear- 

 ing than at the coronary margin (compare fig. 44). 



The height of the wall decreases from the toe to the inflec- 

 tion of the bars, and to a greater proportionate extent in fore 

 than in hind feet. No exact measurements can be given, as so 

 nmch depends on the race, age, use, conformation, etc., of the 

 animal, and great differences may exist without necessarily 

 rendering the hoof abnormal. The length of the toe, as 

 compared with that of the quarters and heels, depends on the 

 angle of the foot, and is about in the proportion of 3 : 2 : 1, as 

 2i : 2 : 1 or as 2 : li : 1. 



The thickness of the wall varies greatly ; from the toe to 



