314 NERVES AND THEIR CONTROL 



2. VOLUNTARY REACTION 



Observations. 1. Send any whispered word around the 

 class. Take the time at instant of starting the word, by the 

 instructor, and also again when received, to determine time of 

 transmission. Divide time of transmission by number in the 

 class. What is the average time of voluntary reaction ? 



2. Let members of class stand and touch hands. The in- 

 structor will now send a touch signal, as a long and short pres- 

 sure of fingers, to imitate a telegraph signal. Get the average 

 reaction time as before. How does it compare with the first 

 or ear reaction ? 



Conclusions. 1. How do voluntary reactions differ from in- 

 voluntary ones ? 



2. How do ear reactions compare with touch reactions ? 



c. Frog 



Observation. 1. Refer back to your study of the frog. 

 What reactions have you noticed? Try to classify them, into 

 voluntary and involuntary. 



Conclusions. 1. Tell how the reactions of the frog compare 

 with those of man; that is, which do you think has the better 

 nervous system? 



2. Show how the note at the beginning of the problem may 

 apply to any animal. 



d. Sources of Knowledge and Action 



Note. " The mind is a collective term for the operations of 

 the nervous system." 



Observations. 1. Touch the back of the hand with a pencil 

 point. 



2. Close the eyes and place on different parts of the tongue 

 several substances, as sugar, vinegar, salt, weak ammonia, etc. 

 What part of the tongue is most sensitive to each? 



3. Test your hearing by determining how far off the tick of 

 a watch can be heard. 



