274 HARVEY CAHR 



make low error scores in every experiment. This consistency 

 is limited to comparatively few animals; irregularity and incon- 

 sistency obtain for the majority of the rats and for the groups 

 taken as a whole. 



Adaptability to these alterations is the general rule. The 

 rate of adaptability is a function in general of the magnitude 

 of the disturbance. Stability of the novel conditions aids 

 adaptation, while any further change delays it; animals kept in 

 a novel situation eliminate the disturbance more quickly than 

 when they are shifted back and forth between the novel and 

 the normal conditions. Continuous alterations of the novel 

 conditions as in the various rotation experiments operate to 

 delay the adaptation. Adaptation to any novel situation is 

 in the main specific and not general ; the animals become adapted 

 to that particular alteration and not to all novel situations. 

 There is no conclusive evidence that the adaptation secured 

 in one experiment operates to give complete immunity in other 

 experiments. Complete adaptation to one series of positions 

 in the rotation experiment did not involve a complete immunity 

 for alterations between another series of positions. Any 

 adaptation to a particular situation is retained with some degree 

 of perfection over a period of time devoted to securing adjust- 

 ments to other novel conditions. Any acquired immunity is 

 thus mainly specific and refers only to that situation under which 

 it was acquired; it is retained after the interpolation of other 

 tests with some degree of perfection, but it gives no certain 

 aid to the mastery of other novel situations. 



The degree of disturbance was a function of the kind of alter- 

 ation. As a general rule alterations while running the maze 

 were more effective than changed conditions of the rat's environ- 

 ment before being placed in the maze. It is rather surprising 

 that pronounced changes in method of handling and of route 

 from cage to maze should be without effect, while alterations 

 of the living cage in relation to its environment were provocative 

 of error. The difference in the results may be due to the fact 

 that the animals were not subjected to a sufficient duration of 

 exposure to the novel conditions in the former two experiments. 

 The maximum duration of exposure never exceeded a few minutes, 

 while the minimum exposure in the cage experiments was fifteen 

 minutes. Covering the maze produced no effect, while con- 



