THE BODY TEMPLE 47 



transmitting it to every part of the body. Each cor- 

 puscle has the ability to carry a load of oxygen much 

 larger than itself. It is only while the corpuscles are 

 loaded with oxygen that the blood is red. It becomes 

 a dark purple color after the oxygen has been removed. 

 It is for this reason that the blood is red in the arteries 

 and dark purple in the veins. 



The colorless portion of the blood, called plasma, 

 contains the various substances out of which the mus- 

 cles, bones, and other tissues are formed. These sub- 

 stances are derived from the food which we eat and 

 digest. This portion of the blood also contains various 

 waste substances, which result from the wear and tear 

 of the body, and are being carried to the several organs 

 set apart for the business of removing them, and thus 

 keeping the vital fluid pure. 



How the Blood Circulates. — The business of the 

 heart is to circulate the blood, which it does so rapidly 

 that a quantity of blood equal to the whole amount in 

 the body passes through the organ every half minute. 

 The heart of a vigorous man pumps not less than three 

 hundred barrels of blood daily, in doing which it ex- 

 ercises as much energy as would be required to lift 

 one thousand stones, weighing one hundred pounds 

 each, from the ground to the shoulder. 



At each heart beat, a wave of blood starts from the 

 heart, and travels to the most remote ends of the arter- 

 ies. "V\^iere the arteries come near the surface, this 

 wave can be felt, and is called the pulse. The pulse 

 rate is usually about seventy beats per minute. It is 

 somewhat more rapid in young children, and is in- 

 creased by exercise. 



The blood starts out from the lower chamber of the 

 left side of the heart, from which it is propelled through 



