AND HOW TO KEEP IT SOUND. 69 



Figs. 21, 22, and 23. — I have been induced to add these 

 figures in consequence of meeting with the foot represented 

 in Fig. 21. It presents such an admirable illustration of 

 the effect of shoeing and stabling upon the frog and elastic 

 cushion, that I could not resist the impulse to draw it and 

 pla^e it by the side of the young foot, already represented by 

 Fig. 6 ; and having done so, I was further led to add a sketch 

 of the interior of the hoof, in the hope that bringing the three 

 figures under notice at one view, might enable me to point 

 out more clearly what changes have taken place, and how 

 they have been brought about. Upon a careful comparison 

 of Fig. 21 with Fig. 22, we shall be struck among other 

 things with the great difference observable in the bulk of the 

 elastic cushion or fatty frog in the two feet — both in the heel 

 at Z», and in the portion immediately between the navicular 

 joint and the horny frog at e. I found, however, a difference 

 in the quality or texture of this part in the two feet of far 

 greater importance than any diminution of quantity, — for 

 while Fig. 22 presented a substance resembling throughout 

 its whole extent a mixture of fat and tendon, and yielded to 

 pressure from the point of a knife without being pierced by it 

 — that is, sunk away before it — the corresponding part in 

 Fig. 21, was of a close unyielding texture, offering the resist- 

 ance of firm gristle, and, instead of sinking away from the 

 point of the knife, resisted it with a grating sound : indeed 

 I could perceive no difference between the sound produced 

 by passing the point of the knife over this substance and over 

 the horny frog. I have attempted to mark where the change 

 of structure commences by a variation in the touch upon the 

 figure, by which it will be seen that the texture of the sub- 

 stance at h is pretty much the same in each foot, notwith- 

 standing the great disproportion between their respective 

 quantities. In Fig. 21, where it has suffered under bad treat- 

 ment, and is wasted and dwindled to almost nothing, it soon 

 assumes a close firm texture as it descends from h towards e 

 — until (all its soft parts having been absorbed) it terminates 

 in the hard mass marked in the figure by checkered lines. 



If we now turn to Fig. 23, and with its assistance contem- 

 plate this part in its situation in the hoof, we shall obtain a 

 clear idea of the relation it bears to the other parts of the foot 

 in general, and the navicular joint in particular. 



a. Is a broad flat mass of horn, projecting upwards into the middle 



of the elastic cushion, and is called the " frog stay." 

 b h. Are two horny projections rising into the cavity of the hoof 



