CHAPTER XVIII 



ANALYSIS OF BEHAVIOR (Continued) 



2. The Nature of the Movements and Reactions 



In the preceding section we have dealt primarily with the causes and 

 conditions of movements and reactions ; here we are to deal with the 

 movements and reactions themselves. 



A. The Action System 



Every organism has certain characteristic ways of acting, which are 

 conditioned largely by its bodily structure, and which limit its action 

 under all sorts of conditions. This perhaps seems a mere truism. 

 Amoeba of course cannot swim through the water like Paramecium, and 

 the latter cannot fly through the air nor walk about on dry land. But 

 the behavior of any given lower organism is actually confined in this way 

 within narrower limits than is frequently recognized. Formulae have 

 at times been proposed to explain the movements of various organisms, 

 when the latter are incapable of performing the movements called for 

 by the formulae. It is usually possible to determine with some approach 

 to completeness the various movements which a given organism has at 

 command. These form as a rule a coordinated system, which we have 

 called in previous pages the action system. The action system of an 

 organism determines to a considerable extent the way it shall behave 

 under given external conditions. Under the same conditions, organisms 

 of different action systems must behave differently, for to any stimulus 

 the response must be by some component of the action system. Thus, 

 Amoeba, the bacteria, Paramecium, Hydra, and the flatworm have ac- 

 tion systems of different character, and their behavior under given con- 

 ditions must differ accordingly. This matter has been dealt with in 

 detail in the descriptive portion of the present work, so that we need not 

 dwell upon it here. In studying the behavior of any organism, the first 

 requisite to an understanding is the working out of the action system. 1 



1 The action system corresponds largely to what Putter (1904) calls the " Symptoma- 

 tology" of organisms. 



