16 FISTULA AND POLL-EVIL 
without change of arrangement into the neck 
and back. Thus pus within the withers after 
filtering downward finds its only exit by trav- 
eling first in either of these two directions, and 
ultimately to the surface of the body at points 
remote from the seat of development. It is 
this complex arrangement that affords the im- 
pregnable intrenchment of pathological prod- 
ucts and that is responsible for the refractory 
character, the extreme seriousness and the un- 
varying chronicity of the disease known as fis- 
tula of the withers. 
_ ‘The Skin 
The skin covering the withers possesses noth- 
ing unusual except the thickness of the subcut- 
em along the median line anteriorly where the 
heavy connective tissue of the mane begins. Pos- 
terior to the summit of the withers the skin is of 
normal thickness, but is separable only with 
difficulty from the aponeurosis of the fleshy 
panniculus whose fixed attachment is at the 
level of the fourth or fifth spine. Very often, 
however, the skin is the seat of scars superven- 
ing harness and collar injuries which fuse it 
into the underlying ligaments, fascia or mus- 
cles as the location may determine. 
Panniculus Carnosis (Cutaneous Muscle) 
This muscular structure is a prominent feat- 
ure of the withers in that its chief attachment 
