322 



COORDINATION AND SENSATION 



10. Compare voluntary and reflex action. In what sense are all the 

 activities of the body reflex ? 



11. In what sense is walking voluntary ? In what sense is it reflex? 



12. How does secondary reflex action lessen the work of the nerv- 

 ous system ? 



13. State the special functions of the nerves, ganglia, spinal cord, 

 bulb, cerebellum, and cerebrum. 



14. State the importance of the 



formation of correct habits. 



PRACTICAL WORK 



To demonstrate Nerve Pathways. 

 A smooth board, 2x6 ft., is painted 

 black, and upon this is drawn in white 

 a life-size outline of the body. Pieces 

 of cord of different colors and lengths 

 are knotted to represent mon-axonic 

 and di-axonic neurons. These are 

 then pinned or tacked to the board in 

 such a manner as to 'represent the con- 

 nections in the different kinds of nerve 

 pathways. Fig. 143 shows such a 

 board with connections for a reflex 

 action and a voluntary action of the 

 same muscle. 



Study of the " Knee Jerk " Reflex. 

 A boy is seated on a chair with the 

 legs crossed. With a small pointer he 

 is given a light, quick blow on the 

 upper margin of the patella at the point 

 of connection of the tendon. The 

 stroke will usually be followed by a 

 reflex movement of the foot. Does 

 this take place independently of the 

 mind ? (The one upon whom the ex- 

 periment is being performed should 

 assume a relaxed condition and make 

 no effort either to cause or prevent the 

 movement.) Can the movement be 



Fin. 143. Nerve board for 

 demonstrating nerve pathways. 



