786 DISEASES AND THEIR TREATMENl'. 



out of twenty-four, and sometimes for sevcnil consecutive days. 

 Let this be compared with the few hours during which the feet of 

 a horse at pasture are in a quiescent state, and there will be no 

 cause of surprise in the change of form and position, and character, 

 and the state of conli'action which takes i>lace in the foot deprived 

 of its natural pressure and motion. 



" The first indication of contraction is the gradual disj^lacement 

 of the navicular and coffin-bones. They ascend within the lioof An 

 unnatural arch is formed by the ascent of the frog, and the delicate 

 synovial membrane lining the joint is crushed and bruised by the 

 ver}^ matei"ial Avhich nature has bestowed as a defense. This bruise 

 of the sj^novial membrane lining the joint is the veritable source of 

 the complaint, the actual cause of the whole not consisting in the 

 wear and tear of the part, but having its origin in rest. It is en- 

 gendered in the stable, but it becomes permanently established by 

 sudden violence out of it. General contraction of the foot of the 

 horse may take place to a great extent with comparative impunity; 

 but it is a ])artial contraction or jiressure which is the root of evil." 



Prof. Williams, our best modern authority, in relation to the 



cause, says: — 



" I have stated my oinnion that generall}^ the alteration of the di- 

 rection of the bony column by the shoe, or by a natural u])i-ight con- 

 formation of pastern, is the great cause. In addition to this violent 

 interference with the designs of nature, the elevation oft he heels fur- 

 nishes additional cause of concussion to those already stated, by 

 removing the frog from the ground; the Irog being elastic, tough, 

 and strong, intended to touch the ground and diffuse concussion, 

 as well as to prevent slipping at each step the animal takes. When 

 left in its natural condition, it is a large, tough, sottish body, giv- 

 ing Avay to the pressure of the fingers Avhen manipulated, expand- 

 ing each time the foot is put to the ground, the commissures at its 

 sides admitting of this expansion Avithout the other jjarts of the foot 

 being interfered Avilh. So long as it touches the ground, the sen- 

 sitive ])arts within, and particularly the navicular bursa, ibr which 

 it furnishes a soft bed, rests upon a resilient body, free from con- 

 cussive danger. Besides furnishing this soft bed, it ])erforms 

 another impoi'tant function, being elastic within and Avithout, it 

 assists the flexors in the first act of elevating the foot from the 

 ground, and it does this in virtue of its inherent poAver of assuming 

 its original shape Avhei\ the superincumbent Aveight is taken aAvay 

 from it. Thus, Avhilst on the ground, and bearing its proportion of 

 weight, it is flattened from side to side, bulging into the commis- 

 sures and cleft, ready at every moA^ement, like a piece of india- 

 rubber, to assume its proper form Avhen the least jiortion of the 

 weight is taken :^'om it. When the flexoi^s are acting, it becomes 

 narroAved from side to side, and deeper from surface to surface, and 

 during this assumption of its natural form, it gives an ujiAvard im- 

 petus to the foot, Avhich is of essential importance to its easy eleva- 

 tion. The removal of this frog pressure during long periods of rest 



