210 ARTERIES, VEINS. 



Questions. 



Is standing a voluntary action ? 



What order of muscles keep us erect ? 



Why do we so soon feel tired by standing ? 



Why is walking easier to us than standing? 



Have you any idea by what means you walk ? 



How do running and leaping differ from walking? 



Can you tell how you manage to leap ? 



What muscles lift us up by their action ? 



What benefit do we derive from exercising our bodies ? 



What is this exercise called? 



Why should we be careful in exercising ? 



LESSON V. 



VESSELS OP THE HUMAN BODY IN GENERAL- 

 ARTERIES VEINS. 



NOTHING is more surprising than the vast num- 

 ber of vessels, filled with different kinds of fluids, 

 which crowd our bodies in every part. If we 

 prick ourselves with the finest needle, blood is 

 sure to follow, a proof that it has wounded some 

 vessel. 



Vessels are tubes having thin yet strong coats. 

 One set of vessels carries the blood from the heart 

 these are called arteries ; another set receives 

 it, and carries it back these are called veins ; a 

 third takes up the nourishing juices from our intes- 

 tines these are called lacteals ; a fourth set rises 

 from the surfaces of the joints and other places, and 



