REGULATION IN BEHAVIOR 345 



regulatory is selected, through the operation of physiological laws, from 

 among many performed by the same individual. In natural selection 

 the same reaction is selected from among many performed by different 

 individuals — in both cases because it is regulatory — because it 

 assists the life processes of the organism. The two factors must then 

 work together and produce similar results.^ In both, the essential point 

 is a selection from among varied activities. 



We must here notice the fact that we often find in organisms be- 

 havior that is not regulatory. How are we to account for this ? With- 

 out going into details, it is clear that there are a number of factors that 

 would produce this result. First, interference with the life processes is 

 not the only cause of reaction. The organism is composed of matter 

 that is subject to the usual laws of physics and chemistry. External 

 agents may of course act on this matter directly, causing changes in 

 movement that are not regulatory. Second, the organism can perform 

 only those movements which its structure permits. Often none of these 

 movements can produce conditions that relieve the existing interference 

 with the life processes. Then the organism can only try them, without 

 regulatory results, and die (see, for example, such a case in the flatworm, 

 p. 244). Further, certain responses may have become fixed, in the way 

 described above, because under usual conditions they produce adjust- 

 ment. Now if the conditions change, the organism still responds by 

 the fixed reaction, and this may no longer be regulatory. The organ- 

 ism may then be destroyed before a new regulatory reaction can 

 be developed by selection from varied movements. This condition of 

 affairs is of course often observed. 



All together, the regulatory character of behavior as found in many 

 animals seems intelligible in a perfectly natural, directly causal way, on 

 the basis of the principles brought out above. We may summarize these 

 principles as (i) the selection through varied movements of conditions 

 not interfering with the physiological processes of the organism ("trial 

 and error"); (2) the fixation of the adaptive movements through the 

 law of the readier resolution of physiological states after repetition. 



3. Requlation in Other Fields 



Is it possible that individual regulation in other fields is based on 

 the same principles that we have set forth above for behavior? Bodily 

 movement is only one of the many activities that vary, and variations 

 of any of the organic acti^vities may impede or assist the physiological 



• For a discussion of the relation of these two factors, see Chapter XIX. 



