GENERAL OBSERVATIONS 65 
screws, moved to the various positions indicated in the 
drawings, the following conclusions were arrived at: 
1. Bewaviour or tHE Coronary Enon. 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 tendency 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, b, 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. Beyaviour or tHE Souar Epex.—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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