RELATION TO PSYCHIC BEHAVIOR 333 



example is the following: Organisms react appropriately to repre- 

 sentative stimuli. That is, they react, not merely to stimuli that are in 

 themselves beneficial or injurious, but to stimuli which lead to bene- 

 ficial or injurious conditions. This is as true of positive as of negative 

 reactions. It is true of Amceba when it moves toward a solid body that 

 will give it an opportunity to creep about and obtain food. It is true of 

 Paramecium when it settles against solids (even bits of filter paper), 

 because usually such solids furnish a supply of bacteria. It is true of 

 the colorless flagellate Chytridium and the white Hydra, when they move 

 toward a source of light and thus come into the region where their prey 

 congregate. There seems to be no general name for this positive re- 

 action to a representative stimulus. In man we call various subjective 

 aspects of it by different names, foresight, anticipation, prudence, 

 hope, etc. 



The fact that lower as well as higher organisms thus react to repre- 

 sentative stimuli is of the greatest significance. It provides the chief 

 condition for the advance of behavior to higher planes. At the basis 

 of reaction of this character lies the simple fact that a change, even though 

 neutral in its effect, may cause reaction (p. 294). This taken in con- 

 nection with the law of the resolution of physiological states (p. 291) 

 permits the establishment of a negative or positive reaction, as the case 

 may require, as a response to a given change. The way in which this 

 may take place we have attempted to set forth on page 316. 



Related to these reactions to representative stimuli are certain other 

 characteristics distinguished in the behavior of man and higher animals. 

 The objective side of memory and what is called habit is shown when 

 the behavior of an organism is modified in accordance with past stimuli 

 received or past reactions given. If the behavior is merely changed in 

 a way that is not regulatory, as by fatigue, we do not call this memory. 

 In memory the reaction is modified in such a way that it is now more 

 adequate to the conditions to be met. Habit and memory in this ob- 

 jective sense are clearly seen in the Crustacea, and in the low accelous 

 flatworm Convoluta (p. 255). Something of a similar character is seen 

 even in the protozoan Stentor. After reacting to a weak stimulus which 

 does not lead to an injurious one it ceases to react when this stimulus 

 is repeated, while if the weak stimulus does lead to an injurious one, 

 the animal changes its behavior so as to react next time in a more effec- 

 tive way; and it repeats this more effective reaction at the next inci- 

 dence of the stimulus. Habit and memory, objectively considered, 

 are based on the law of the resolution of physiological states (p. 291), 

 which may be set forth in application to the present subject as follows : 

 If a given physiological state, induced by a stimulus, is repeatedly 



