THE METHOD OF REGULATION IN BEHAVIOR AND 

 IN OTHER FIELDS. 



BY 



H. S. JENNINGS. 



The results set forth in the preceding paper, together with 

 certain other relations found in the behavior of lower organisms, 

 that have been detailed in previous papers by the present writer, 

 suggest a certain point of view in regard to the general method 

 of regulation or adjustment in organisms. Everywhere in the 

 study of life processes we meet the puzzle of regulation. Organ- 

 isms do those things which advance their welfare. There are 

 some exceptions, but this is certainly true in a general survey. 

 If the environment changes, the organism changes to meet the 

 new conditions. If the mammal is heated from without, it cools 

 from within; if it is cooled from without it heats from within, 

 maintaining the temperature that is to its advantage. The dog 

 which is fed a starchy diet produces digestive juices that are rich 

 in the enzyms which 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 biology. How can the organism thus provide for its own needs ? 

 To put the question crudely, how does- it know what to do when a 

 difficulty arises, so as to overcome this difficulty.^ 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, 

 determining 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 character that has given us the theories of 

 vitalism. By these theories the principles controlling the life 



