242 COMPARATIVE PHYSIOLOGY OF THE BRAIN 



solving of the problem as to whether sensations of 

 space are purely a matter of memory, as Helmholtz, 

 among others, assumes, or whether they are deter- 

 mined by inherited structural conditions, as Hering, 

 for instance, maintains. The question is of great im- 

 portance for the further investigation of the mechanics 

 of the brain, and for this reason we mention it in 

 passing. It has been assumed that space-sensations 

 are acquired because the new-born infant does not 

 immediately show signs of orientation in space. The 

 fact is overlooked that the new-born infant comes into 

 the world incomplete that is to say, certain structures 

 become complete during the first year or even later. 

 The same erroneous conclusion was drawn in regard 

 to walking. The child was supposed to " learn " to 

 walk. The fact that the chick can walk when it 

 comes out of the egg would have sufficed to prevent 

 this error on the part of the empiricists, if physiolo- 

 gists had earlier appreciated the importance of com- 

 parative physiology. The difference between the 

 chick and the human suckling consists in the fact that 

 the structural development of the former is more 

 complete at the moment of hatching than the struct- 

 ural development of the latter at the time of its 

 birth. The child can begin to walk only when the 

 nerves, muscles, etc., have reached the required de- 

 gree of development. The same is true of visual 

 space-perception. The newly hatched chick has vis- 

 ual perception ; that is, it picks at points that differ 

 from their environment in colour and intensity of light. 



