THE PERCEPTION OF SPACE. 



245 



the original color by the inducing color is due to the dis- 

 appearance of the jjhysiological conditions under which the 

 first color was produced, and to the induction, under the 

 new conditions, of a genuine new sensation, with which the 

 * suggestions of experience ' have naught to do. 



Fig. 64. 



That processes in the visual apparatus propagate them- 

 selves laterally, if one may so express it, is also shown by 

 the phenomena of contrast which occur after looking upon 

 motions of various kinds. Here are a few examples. If, 

 over the rail of a moving vessel, we look at the water rush- 

 ing along the side, and then transfer our gaze to the deck, a 

 band of planks will appear to us, moving in the opposite 



