504 'Journal of Comparative Neurology and Psychology. 



may cease to act, but until the appropriate reaction is given 

 let the organism be such that it runs through the gamut of 

 the others until the appropriate reaction is brought about. As 

 there are N possible reactions the chances are that the appropriate 

 reaction will be given before all N are performed. At the next 

 appearance of the stimulus, which we may call Sj, those reactions 

 which were in the last case performed, are, through habit, more 

 likely to be again brought about than those w^hich were not per- 

 formed. Let u stand for the unperformed reactions. Then we 

 have N-w probable reactions to So. Habit rendering the previously 

 most performed reactions the most probable throughout we should 

 expect to find the appropriate reaction in response to: 



Si contained in N. 



52 contained in N-Wi. 



53 contained in N-Wi-W2- 



Sn contained in N-ww, which approaches one as a limit. 



Thus the appropriate reaction would be fixed through the laws 

 of chance and habit. This law of habit is that when any action 

 is performed a number of times under certain conditions it be- 

 comes under those conditions more and more easily performed. 



There are two main roads leading to the hypothesis of animal 

 consciousness. One is traveled by the psychologist in his effort 

 to extend the limits of the introspective science, and the other is 

 followed by the biologist who would find in the conscious fiat some 

 explanation of selective movements or of regulation in behavior. 

 Hence the criteria of consciousness applied by the two investi- 

 gators are different. 



LoEB* holds that a psychology of the lower forms must be a 

 science of tropisms, and that even in the higher forms conscious- 

 ness is no explanation of behavior but merely a function of the 

 mechanism of associative memory.^ Whether or not the behavior 

 of any form of life has a definite significance to the psychologist, 

 the complexity of its functions must decide its rank in a science of 

 behavior, and for this classification the limits of such complexity 



*Loeb: Dynamics of living matter, p. 158. 

 « Ihid., p. 6. 



