GENEEAL OBSEEVATIONS 65 



screws, moved to the various positions indicated in the 

 drawings, the following conclusions were arrived at : 



1. Behaviour of the Coronary Edge. — During uniform 

 weighting of all four hoofs the coronary edge shows a 

 tendency to contraction in the anterior and lateral regions 

 of the hoof, and a tendeaicy to expansion posteriorly. With 

 heavy weighting of the hoof, which is shown by a backward 

 inclination of the fetlock, contraction in the anterior and 

 lateral regions is slight, but the expansion behind, in the 

 region of the heels, is distinct, commencing gradually in 

 front, becoming stronger, and diminishing again posteriorly. 

 The coronary edge of the heels becomes slightly bulged 

 outwards. The bulbs of the heels swell up and incline a 

 little backwards and downwards. 



When the fetlock is raised the expansion of the coronary 

 edge of the heels disappears from behind forwards, passing 

 forwards like a fluid wave. In the lateral and anterior 

 regions of the coronary edge the contraction disappears ; 

 and when the weight is thrown off the foot it passes into a 

 gentle expansion of the coronary edge of the toe. During 

 the opposite movement of the fetlock, that of sinking 

 backwards, this change of form is executed in the converse 

 manner. 



In short, the coronary edge resembles a closed elastic 

 ring, which yields to pressure, even the most gentle, of the 

 body-weight, in such a way that a bulging out of any one 

 part is manifested by an inward movement of another 

 part. 



In Fig. 37, h, the dotted line represents the changes of 

 form in comparatively well-formed and sound hoofs at the 

 moment of strongest over-extension* of the fetlock- joint. 



2. Behaviour of the Solar Edge. — Under the action of 

 the body-weight this is somewhat different from that of 

 the coronary edge. Anteriorly, and at the sides, as far as 

 the wall forms an acute angle with the ground, the tendency 



* The term 'over-extension,' as employed by Lungwitz, is intended 

 to indicate that position assumed by the fetlock-joint when the opposite 

 foot is raised from the ground. 



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