REDINTEGRATION IN ALBINO RAT— A STUDY IN RETENTION 63 



individual may be placed in the same environment, but 

 repertoire of actions is so limited that the individual can 

 not respond. Examples of each of these cases may be 

 seen in records of the inclined plane already cited, where 

 some learned rapidly, some more slowly, and some failed 

 entirely. 



In regard to responses of individuals, as above con- 

 sidered, it is an open question whether the muscular or 

 the sensory aspect of the endowment is the most important. 

 The object of the sensory experiments by Vincent (22) 

 and others would indicate that the response of the individual 

 in the acquirement of the maze habit, for example, is for 

 the most part sensory. It is undeniable that the sensory 

 endowment of the individual conditions reception of stimuli 

 to a great extent; but the fact should not be over- 

 looked that the muscular endowment of movement is of 

 equal if not of greater importance, because upon this 

 the habit depends first and always, while the sensory 

 response is confined more particularly to the beginning 

 of the learning. Individual differences in endowment 

 would thus result in individual differences in behavior, 

 in the establishment of integrations, as may be seen in 

 the number of " errors," in rapidity of the process of 

 establishing integrations, as may be seen in the number 

 of trials and in speed of movement, and as may be seen in 

 the time totals. This is true because of the persistence 

 of the dominant " error," and the difficulty of the rat 

 to establish the integrations of movement at the locus of 

 dominant " error." For example, the rat has all the sen- 

 sory cues of going to the plane and coming from the plane 

 after it is plunged, and these are usually established at 

 approximately the 9th trial, yet the integrated movement 

 of plunging the plane is not yet established. Evidently 

 the sensory cues are present, but integrated movement 

 required in plunging the plane remains imperfect for 

 many subsequent trials. 



Numerous other cases could be cited to illustrate con- 

 cretely the fact that scarcely, if ever, are two individuals 

 found to exhibit the same behavior in any given environ- 

 ment. One individual may learn as rapidly as another, 



