333 



CHAPTEE I. 



PECULIARITIES IN THE ANATOMY AND PHYSIOLOGY OF THE DOG. 



The Skeleton including the Teeth. — The Muscular System. — Tiie Brain and 

 Nervous System. — The Digestive System. — The Heart and Lungs. — The 



Skin. 



THE SKELETON*, INCLUDING THE TEETH. 



In the skeleton of the 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 everj" thorax, as this part is called scien- 

 tifically, is that of dilatation and contraction, bj^ 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 in- 

 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 arises 

 that a narrow-chested horse or dog may have better wdnd 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 greatest 

 expansion, and though it can contract it cannot dilate its volume, 

 while the chest that is too flat can expand rapidly, but then it 



* See next page. 



