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THE AMERICAN NATURALIST [Vol. LIV 



pletely disappeared after a few trials. In brief, the whole 

 series of any one of the subjects here reported displayed 

 an increasing degree of freedom and precision of move- 

 ment, as time went on. All subjects were tested for 

 equilibration after a series had been completed and all 

 responded to being thrown and dropped just as alertly as 

 before rotation. 



It is hazardous to draw general conclusions from an in- 

 troductory study of this kind. Our problem does, how- 

 ever, bear directly and significantly upon the functional 

 integrity of the equilibratory mechanisms. The facts 

 above presented support the contention that nystagmus 

 is closely related to the other organic responses to rota- 

 tion and that it is dependent, as are these other responses, 

 upon a large group of factors. Furthermore, we have 

 found that after-nystagmus in the white rat decreases in 

 intensity and duration (a) from day to day and (b) 

 within the series of a single day. Either intensity or 

 duration may be modified also by certain organic condi- 

 tions, e. g., nausea, by speed and number of rotations, and 

 by such general conditions as antecedent rest and fatigue. 

 The decrease and disappearance of nystagmus are accom- 

 panied by a disappearance of the characteristic rotational 

 posture and of other bodily disturbances, the disappear- 

 ance being signalized by the reappearance of the usual 

 exploratory movements and by such specific events as the 

 scratch-reflex. 



Fisher and Babcock tried to explain away the demon- 

 strated loss of after-nystagmus under repetition (a) by 

 charging that the human subjects were " pathological" 

 and (b) by referring the observed decrease to a vicious 

 practise acquired by "a few subjects" of "gaze-fixing" 

 upon a "distant object." It is not clear just how their 

 explanation can be extended to the white rats. 



