No. 635] 



BODILY ROTATION 



533 



inhibition of all movement and a tenseness of position 

 leading to what one might call the ' ' rotational posture. ' ' 

 There is no change in the position until the end of the 

 after-nystagmus, save that the head swings to the oppo- 

 site side as rotation ceases. This second type of response 

 can be easily induced in subjects manifesting the first 

 kind by slightly increasing the speed of rotation. As the 

 series proceeds, the more striking features of the rota- 

 tional posture begin to drop out. The head tends to swing 

 less and less in the direction opposite to rotation and very 

 early the return movements — even the bringing of the 

 head back to a straight position — disappear. Finally, 

 the original swing itself becomes quite listless and may 

 not occur at all provided the attention of the rat is else- 

 where directed. The exploratory movements return 

 slowly, beginning with the post-rotary period and finally 

 entering the rotary period itself. 



5. The scratch-reflex affords an excellent indication of 

 the extensity and intensity of the bodily disturbance pres- 

 ent during, and subsequent to, rotation. Early in a series, 

 a scratch movement initiated before rotation is suddenly 

 arrested as rotation begins. I have not observed any 

 scratching during the earlier trials of a series. Subject 

 "J" endeavored to scratch on the fourth day's rotation; 

 but the effort was poorly localized and uncoordinated. 

 At the end of the series, an accurately localized scratch- 

 movement was begun and carried to completion by sev- 

 eral subjects, and successful attempts were frequently 

 made to cleanse the face, etc., in spite of rotation or stop- 

 ping. As the exploratory movements came back to their 

 own, the rat frequently stretched up on its hind legs. In 

 such a position, the stopping of rotation caused a definite 

 compensatory reaction on the part of the rat; but there 

 was nothing here to indicate that this was more than a 

 natural response to the effect of inertia. All of the spas- 

 modic and uncoordinated qualities of an early event of 

 this kind were gone. The tendency of some of the sub- 

 jects to run in the direction opposite to rotation com- 



