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CHAPTER I. 
PECULIARITIES IN THE ANATOMY AND PHysioLocy OF THE DOG. 
The Skeleton, including, the Teeth—The Knee System—The Brain and 
Nervous System—The Digestive System—The Heart and Lungs—The 
Skin. 
THE SKELETON,* INCLUDING THE TEETH. 
In the skeleton ofthe dog, and in that of the horse, as well as of 
all other animals remarkable for their speed, there is a peculiar 
formation of the chest which deserves to. be noticed. The prin- 
ciple of construction in every thorax, as this part is called scien- 
tifically, is that of dilatation and contraction, by which its entire 
contents are lessened or increased, and thereby air is made to pass 
in and out. In man this is chiefly caused by the front of the 
chest rising and falling, and in this way increasing the diameter 
from before backwards, but in the dog, horse, deer, -&c., the im- 
crease is from side to side, the ribs being sickle-shaped, and. acting 
‘laterally like the gill-covers of a fish. From this it often ariges 
that a narrow-chested -horse or dog may have better wind than 
‘another with a round barrel, because he is able to alter the cubic 
contents of his chest more rapidly, and thus inspire and expire 
a larger volume of air. “A round barrel is nearly at its greatést 
expansion, and though it can contract it cannot dilate its volume, 
while the chest that is too flat can expand rapidly, but then it 
has not the power of contraction beyond its natural limits. A 
“medium transverse diameter is therefore to be desired, and is 
practically found to. de advantageous, i in allowing a better action 
of the shoulder-blades rolling: upon the surface on each side: On 
the ‘other hand, man requires great depth of chest from | before 
* See next page. 
