8 To show that sensitiveness to temperature may be influenced by temporary 

 conditions, place both hands in a basin of lukewarm water, after one hand has 

 been for a time in very hot water, while the other has been kept in cold water. 

 Describe the sensations in each hand and explain the difference between them. 



9 To observe your own progress in learning, time yourself on successive 

 efforts to perform a given task — as writing the alphabet backwards — until further 

 progress is no longer possible. Plot a graph to show the relation of the number 

 of trials to the reduction in time of performance. 



QUESTIONS 



1 How is an organism equipped to receive significant stimuU, external and 

 internal? 



2 To what kinds of stimuli do the specialized sense organs of higher 

 animals respond? 



3 What kinds of organs act as effectors? 



4 What is a reflex arc? 



5 What is meant by a chain of reactions? 



6 What is known about the nature of the impulse transmitted by different 

 nerve cells? 



7 Of what does the central brain-spine system consist? 



8 How are the voluntary movements of our bodies brought about? 



9 In what respects is the autonomic nervous system like the brain-spine 

 system? In what respects different? 



10 How are the activities of the specialized organs and tissues of higher 

 animals co-ordinated? 



11 How do modern living conditions bring special dangers to our sense 

 organs ? 



300 



