Spatially Determined Reaction 243 



sioned by rays from several different directions acting 

 simultaneously, should issue at once in a resultant move- 

 ment. Would not the accompanying consciousness be 

 a single resultant sensation, rather than a complex of 

 spatially ordered elements? It is a good deal easier, of 

 course, to ask than to answer such questions. 



Again, the power of getting true spatial images seems to 

 be bound up closely with the power of moving the sensitive 

 surface. We get our best tactile space perceptions through 

 active touch, involving movement of the hands and fingers ; 

 our visual space perceptions are profoundly influenced by 

 eye movements. Where the movements of an animal's 

 body as a whole are very rapid, as in the case of winged 

 insects, this fact may compensate for the immovability 

 of its eyes. Forel, as we have seen, thinks that insects 

 which can explore objects by moving the antennae, bearing 

 the organs of smell, over them, may have smell space per- 

 ceptions, such as are unknown to our experience ; they may 

 perceive the shape and size of odorous patches as we could 

 do if our organs of smell were on our hands (233). Now, 

 movement of a sense organ brings about the same result 

 that movement of a stimulus across a resting sense organ 

 does ; that is, the stimulus affects different points of the 

 sensitive surface in succession. But the vital significance 

 of the two is quite different ; movement of an object across 

 a resting sense organ means very likely that the object is 

 alive; it must be instantly reacted to, and the speed of 

 the reaction is unfavorable to the formation of a true 

 space perception. Movement of the sense organ, however, 

 gives a series of impressions on successive points of the sensi- 

 tive surface, from a resting object. While the sense organ 

 is being moved, it is probable that other reactions of the 

 animal will be suspended. Whether any part in the forma- 



