CHAPTEE XI 



BEHAVIOR AND BODY TEMPERATURE 



Behavior is the term used to characterize the move- 

 ments which animals make in response to stimuli. In 

 general behavior shows adaptation in that it is so cor- 

 related with usual environmental changes that it helps 

 an animal to iind food, escape dangers, and produce off- 

 spring. By behaving in accordance with its hereditary 

 pattern an animal usually continues to live. Considering 

 the animal kingdom as a whole, behavior becomes more 

 complex and nervous control becomes of increasing im- 

 portance. The protozoa depend on cell responses; 

 sponges have tissues which act as responding units; 

 coelenterates have their behavioristic responses con- 

 trolled to some extent by a rather loosely coordinated 

 nerve net ; worms show increasing domination of activi- 

 ties by polarized neurones which make up the ganglionic, 

 segmental type of nervous system, which is so character- 

 istic of annelids and reaches its climax in arthropods; 

 the tubular central nervous system of chordates readily 

 lends itself to the building up of controlling centers which 

 produce general responses in particular types of organs, 

 rather than in particular bodily segments (Parker, 1919). 

 JYet in the most complex and highly coordinated of ani- 

 mals there are certain types of behavior which remain 

 primitive. Even in man, where a specialized brain has 

 made it possible for intelligence to serve as the finest 



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