THE FORE LDIBS. 81 



the cone and extending backwards. The cone is 

 made np of bones, having the backbone and upper 

 end of the ribs for a roof, the ribs for sides and the 

 breast bone for the floor. This bony framework 

 contains those vital organs, the heart and lungs. 

 In animals used for speed and power the chest must 

 be very large, because speed and power expend much 

 oxygen, which the lungs have to procure for the 

 blood from the atmosphere. As the blood feeds 

 upon oxygen and consumes more when the body is 

 in active movement, it is necessary that the heart 

 be large and strong to receive and send the blood 

 in large quantities to its airing or feeding ground, the 

 lungs ; also that the lungs be large to receive both 

 it, also the air from without, which has to meet the 

 blood and deliver up most of its oxygen to the blood, 

 and in return receive impurities from the blood and 

 carry them from the lungs. Besides being large 

 and strong, the heart and lungs have to submit to 

 quickened rhythmical movement during the exercise 

 of speed and power, therefore we have to see that 

 the walls of the chest, which we saw were formed 

 by the ribs, are freely moveable. 



71.— The belly contains the organs for the con- 

 version of food into the substantial elements for re- 

 pair of the waste of tissue which the body is always 

 undergoing, but which goes on more quickly when 

 the animal is in greater activity. These organs are 

 for the most part, the stomach and intestines witli 

 the largest gland of the body, namely, the liver. 



G 



