CHAPTER XXI 

 BEHAVIOR AS REGULATION, AND REGULATION IN OTHER FIELDS 



i. INTRODUCTORY 



EVERYWHERE in the study of life processes we meet the puzzle of 

 regulation. Organisms do those things that advance their welfare. If 

 the environment changes, the organism changes to meet the new condi- 

 tions. If the mammal is heated from without, it cools from within ; if 

 it is cooled from without, it heats from within, maintaining the tempera- 

 ture that is to its advantage. The dog which is fed a starchy diet pro- 

 duces digestive juices rich in enzymes that digest starch ; while under a 

 diet of meat it produces juices rich in proteid-digesting substances. 

 When a poison is injected into a mouse, the mouse produces substances 

 which neutralize this poison. If a part of the organism is injured, a 

 rearrangement of material follows till the injury is repaired. If a part 

 is removed, it is restored, or the wound is at least closed up and healed, 

 so that the life processes may continue without disturbance. Regulation 

 constitutes perhaps the greatest problem of life. How can the organism 

 thus provide for its own needs? To put the question in the popular 

 form, How does it know what to do when a difficulty arises ? It seems 

 to work toward a definite purpose. In other words, the final result of 

 its action seems to be present in some way at the beginning, determin- 

 ing what the action shall be. In this the action of living things appears 

 to contrast with that of things inorganic. It is regulation of this charac- 

 ter that has given rise to theories of vitalism. The principles control- 

 ling the life processes are held by these theories to be of a character 

 essentially different from anything found in the inorganic world. This 

 view has found recent expression in the works of Driesch (1901, 1903). 



2. REGULATION IN BEHAVIOR 



Nowhere is regulation more striking than in behavior. Indeed, the 

 processes in this field have long served as the prototype for regulatory 

 action. The organism moves and reacts in ways that are advantageous 

 to it If it gets into hot water, it takes measures to get out again, and 



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