328 
ILLUSTRATED STOCK DOCTOR. 
appearance as regards breadth of forehead and prominence of the eye. 
This design of nature is intended for the base of the horns, though in 
breeds known as hornless, or polled, the same formation is observable. 
The room from eye to eye is occasioned by the frontal bones (5, 5, of 
polled sheep) reaching as far below the range of vision as above it, and 
very materially shortening the nasal (10, 10,) bones. These reach up- 
ward to the parietal bones (2) which latter constitute an important portion 
of the posterior, slanting portion of the skull, just below the junction of 
the frontal and parietal bones ; the head falls off in fullness — a backward 
sloping, so to speak, and the part of the frontal bone most important be- 
cause covering the brain, is removed from the danger resulting from 
concussion of the head in fighting. The form of the brain in the sheep, 
is similar to that of the horse and ox, but is longer in proportion to size, 
and broader in the back than in the front. The brain of the sheep so 
closely resembles, in its conformation and structure, that of aman, though 
smaller in proportion, that it furnishes the medical student with a good 
substitute for the human subject. The membrane covering the brain i 3 
technically called the pia mater. The dura mater lines the skull , and be- 
tween the latter and the former is a delicate membrane called ternica 
arachmides. The nerves, of which ten pairs are connected with the brain, 
and thirty with the spinal cord, supply the sense of feeling, seeing, hear- 
ing, tasting, smelling, &c., and a portion conveying the volition of the 
brain to all parts of the body, are termed nerves of motion. 
Diseases of tho Head and Brain. 
In Europe, and especially in Great Britain, sheep arc subject to a long 
category of diseases. Fortunately, in this country sheep thus far have 
been subject to comparatively few diseases, and especially so in the West ; 
owing probably to the fact that, except in the Spring, and sometimes for 
a short period in the Autumn, the climate and the soil are dry. Mr. 
Spooner, the able English veterinary writer, remarks upon the rarity of 
inflammatory diseases in American sheep. This he attributes to tho 
muscular and vascular structure of the sheep, comparing the indifferently 
kept sheep of his day with highly fed British sheep. The real cause, 
however, of exemption from disease lies more in the climate than anything 
else. Another special reason probably is that our flock masters are, as a 
rule, men of intelligence, who trust but little to ignorant shepherds, as 
is not the case in Great Britain and on the continent. We shall therefore 
touch lightly upon mail}” diseases specially treated of in foreign works, 
and pay more particular attention to that class of diseases most prevalent 
with us, 
