252 BODY CONTROL AND HABIT FORMATION 



Close your eyes and allow some one to place bits of various 

 substances on your tongue. Can you distinguish between the 

 different substances? 



Look at this page. How do you get your knowledge of what is 

 on this page? 



At how great a distance can you hear a watch tick? 



Conclusion. — Through what organs do we become aware of 

 the world around us? 



Problem 221 : To determine what parts of the tody are most 

 sensitive to {a) touch, (6) heat and cold. 



a. Touch 



Materials. — Compass. 



Method and Observations. — Blindfold a pupil. Then lightly 

 touch the back of his hand with the two points of a compass. 

 Begin with them close together and gradually move them apart. 

 Have the blindfolded subject tell as soon as the points appear to 

 the touch as two. Experiment further on different parts of the 

 body, and record the results in the form of a table. 



Conclusion. — ■ Which part of the body seemed most sensitive 

 to touch? 



b. Heat and Cold 



Materials. — Large wire nail, pen, ink, and ruler. 

 Method and Observations. — With a ruler and a pen, draw a 

 square inch on the under side of your wrist. Heat a wire nail so 



