72 H. G. Knbs 



are a number of investigators, however, who insist that for the sake 

 of a more objective interpretation of the facts of behavior, more 

 emphasis must be given to the orienting force of the external 

 stimulus. Loeb ('88) observing that the hehotropism of many 

 animals was singularly akin to similar phenomena exhibited by 

 plants, suggested that the orienting function of lines of force (lines 

 of diffusion, 1903) expressed by the equation F (i), playing upon 

 asymmetrical parts of an organism would account for the more 

 precise movements exhibited concomitantly with the impinge- 

 ment of the stimulus involved; the "positive" or "negative" reac- 

 tions. Bohn in a series of excellent papers, and many other inves- 

 tigators, in this field, have shown conclusively that the directive 

 force of any reaction which follows any sort of stimulation can be 

 predicted only by a knowledge of the play of the previous forces 

 acting upon the animal economy; by a careful estimate of the 

 arrangement of characteristic internal aggregates which Jennings 

 denominates as the physiological states. A more intimate knowl- 

 edge of these shifting aggregates called physiological states is cer- 

 tainly essential to any far-reaching interpretation of behavior. 

 Our own data does not admit the classification of any of the move- 

 ments of iEolosoma as "orientation" in the tropic sense of the 

 term. Loeb ('97) appreciating this difficulty, added another fac- 

 tor in behavior which he called Unterschiedsempfindlichkeit; 



represented by the formula F , . This factor, however, throws 



at 



the interpretation back to the physiological states, which are 

 included in our analysis as given above. 



More recently Walter ('07), probably representing the view of a 

 number of investigators, defines the theory of "tropisms" as essen- 

 tially based upon "an asymmetrical reaction to an asymmetrical 

 stimlus." Granting to this view all that he would include we 

 seriously question whether such a comprehensive statement can 

 throw much light on the problem of behavior. Any flexible move- 

 ment in nature, whether exhibited by what we call a living object 

 or a dead, may readily be adjusted to this category without 

 acquiring any added significance thereby. There is a wide dis- 

 tinction between an interpretation of a reflex movement as a reac- 



