PROBLEM I. The S}?fiplest For7m of Behavior in Animals 267 



9. Describe a case of reflex behavior in an ameba. Name five stimuli 

 that can cause a response in a paramecium. 



10. Why do the responses of paramecia seem to be intelH^cnt? 



11. Make four or five short statements to sum up this problem. 



Exercises 



1. Why is the knee jerk an example of a simple human reflex? Let 

 someone gently tap your knee just below the kneecap when your legs 

 are crossed. What happens? Can you keep from jerking your leg when 

 the knee is tapped? Explain. 



2. In a fairly dark room, examine the pupil of a student's eye. Then 

 direct the beam of a flashlight into it. Explain what happens. 



3. What type of behavior is displayed by the secretion of saliva? This 

 experiment will be especially successful before lunch or late in the after- 

 noon. Display some tempting portion of food or talk about food. What 

 happens? What receptors are stimulated? Which efl^ectors respond? 



4. (a) How do paramecia respond to various chemicals? You should 

 have a rich paramecium culture for all these experiments. See directions, 

 page 69. Find a paramecium which has come to rest near some food 

 particles. Run a drop of blue fountain-pen ink slowly under the cover 

 glass. Observe the surface of the animal closely. What do you see? How 

 do these structures differ from the cilia? Under natural conditions 

 the trichocysts are used for protection. What is the stimulus? What is the 

 response? Is the behavior you have just seen useful or harmful to the 

 organism? (h) Now run a drop of red ink under the cover of a second 

 slide. What do you observe? Do all foreign chemicals seem to produce 

 the same response? What objections might be raised to drawing conclu- 

 sions from what you observe? Explain fully. 



5. If you have a microprojector, project some paramecia on the screen 

 and run a weak electric current through the water. What is the response 

 of the paramecia? If other protozoa are available find out whether they 

 respond in the same way. 



6. Can you devise an experiment to show the response of protozoa to 

 light? Try it and record your observations. Discuss the experiment with 

 the class. 



7. Discuss the following: (a) If you create a current in the water and 

 the paramecia are pulled along by the current, is their movement a reflex 

 act? Why or why not? (b) Although in instinctive behavior an animal 

 generally responds "correctly" to its environment, under what circum- 

 stances may this type of behavior not be useful to the animal? (c) Cite 

 some instinctive behavior that is injurious or fatal to an animal. Why 

 has the species not died off as a result of this instinct? (d) How could 

 you determine whether a particular act is an unlearned reflex or an act 

 which depends on intelligence? 



