244 The Animal Mind 



tion of that complex conscious content which we call a 

 spatial image, consisting of different sensations simul- 

 taneously apprehended, is played by the " las ting over" 

 of the impressions on one sensitive point after the stimulus 

 has passed on to the next, a phenomenon which we find 

 both in touch and in sight sensations, it is impossible to 

 say. We are, however, apparently justified in the state- 

 ments that the essence of space perception, as distinct from 

 other conscious processes that may accompany spatially 

 determined reactions, is the presence of an image in the 

 sense above defined, and that a movable sense organ is 

 an important condition for the production of such an image. 



