312 BEHAVIOR OF THE LOWER ORGANISMS 



3. RESUME OF THE FUNDAMENTAL FEATURES OF BEHAVIOR 



We have considered in the three foregoing chapters, first the deter- 

 mining factors of movements, and second the movements themselves. 

 Let us now attempt to put together the most important points in both, 

 so as to reach a general characterization of behavior. 



The three most significant features of behavior appear to be (i) the 

 determination of the nature of reactions by the relation of external 

 conditions to the internal physiological processes, and particularly the 

 general principle that interference with these processes causes a change 

 in behavior; (2) reaction by varied or overproduced movements, with 

 selection from the varied conditions resulting from these movements 

 or, in brief, reaction by selection of overproduced movements ; (3) the 

 law of the readier resolution of physiological states after repetition. The 

 first of these phenomena produces the regulatory character of behavior. 

 The second and third furnish the mainsprings for the development of 

 behavior, the second being constructive, the third conservative. 



The activity of organisms we found to be spontaneous, in the sense 

 that it is due to internal energy, which may be set in operation and even 

 changed in its action without present external stimuli. In reactions 

 this energy is merely released by present external stimuli. What form 

 the activity shall take is limited by the action system, and within these 

 limits is determined by the physiological state of the organism. Physio- 

 logical states depend on many factors. The two primary classes of 

 states depend on whether the internal life processes are proceeding unin- 

 terruptedly in the usual way. Interference with these processes produces 

 a physiological state of a certain character ("negative"), while release 

 from interference or assistance to those processes produces a different 

 state ("positive"). Within or beside these contrasted primary classes, 

 many subsidiary variations of physiological condition are possible, each 

 with its corresponding method of behavior ; at least five of these have been 

 distinguished in a unicellular organism. Any change, external or in- 

 ternal, may modify the physiological state, and hence the behavior. 



The effects of external agents depends largely on their relation to the 

 normal course of the life processes whether aiding or interfering, 

 or neither. A primary fact is that interference with the life processes 

 produces progressive changes in physiological state, inducing repeated 

 changes in behavior. This is in itself regulatory, tending to relieve the 

 interference, whether due to internal or external causes ; it is a process 

 of finding a reaction fitted to produce a more favorable condition. When 

 through such changes a fitting reaction is found, the changes in physio- 

 logical state and hence of behavior cease, since there is no further cause 



