ture. It is the result of the interaction of such organisms 

 and their media. The organism and the media constitute a 

 manifold which, though constantly operating, so functions as 

 to prevent disintegration of the organism. The life-long sta- 

 bility of arrangement possessed by the organism and its 

 offspring further differentiates it from the media and makes 

 most significant the distinction between biology and the 

 inorganic sciences. The field of the science of animal be- 

 havior of which the processes in such a manifold constitute 

 the data, is in part hardly to be distinguished from some of 

 the subject-matter of dynamic biology. The former science, 

 however, always classifies these processes on the basis of the 

 regulation which they display. 



Negative Regulation 



Regulation occurs when any process in the manifold 

 which reduces the stability of the organism results in such 

 a change, either in the media (through the organism's mi- 

 gration or otherwise) or in the organism itself, that the 

 stability of the organism is regained, so that the deviation 

 toward instability has come to be the cause of its own remedy. 

 Such regulation is the avoidance of those states in the or- 

 ganism or of those conditions in the media which are or have 

 become unfavorable to the stability of the organism, so let 

 us call it negative regulation. 



Frequent examples of negative regulation are found in 

 the behavior of inorganic manifolds, of plants, and of the 

 lower animals. When a boat in a heavy sea rolls to one side 

 it rights itself into the perpendicular again. It does this 

 because of the fact that the further it tilts from the per- 

 pendicular the greater is the leverage by which the pull of 

 gravity, which tends to bring it back, is applied. Its behavior 

 conforms to our definition of negative regulation. The way 

 in which paramoecium retains favorable conditions must be 

 described by the same principle. 2 The valve action at the 

 boundary of the optimum will work for the animal's good in 



2Jennings, "Behavior of Lower Organisms." 



[FOUR 



