1 82 COMPARATIVE PHYSIOLOGY OF THE BRAIN 



does not fly into the flame out of " curiosity," neither 

 is it " attracted " by the light ; it is only oriented by it 

 and in such a manner that its median-plane is brought 

 into the direction of the rays and its head directed 

 toward the source of light. In consequence of this 

 orientation its progressive movements must lead it to 

 the source of light. 



We now come to the most important question in 

 this chapter, namely, the relation of the central 

 nervous system to the instincts. As long as such 

 apparently complex things as the instincts are not 

 analysed but treated as entities, it is easy to believe 

 that they are based upon very mysterious nervous 

 structures. It would harmonise with the centre- 

 theory to assume for the moth a " flying-into-the- 

 tlame centre," * and to seek for its localisation in the 

 central nervous system. The fact that the flying of 

 the moth into the flame is nothing but positive helio- 

 tropism, and the fact that the positive heliotropism of 

 animals is identical with the positive heliotropism of 

 plants, proves that this reaction must depend upon 

 conditions which are common to animals and plants. 

 Plants, however, possess no central nervous system, 

 therefore I believe that it is impossible for the helio- 

 tropic reactions of animals to depend upon specific 

 structures of the central nervous system. It is much 



'Steiner tries indeed to "explain" the righting motions of the starfish by 

 the assumption of a "righting centre " in the central nervous system. He 

 does not consider the possibility that contact stimuli and the irritable structures 

 at the periphery may be sufficient for this reaction, and that the nerves act 

 only as protoplasmic conductors between the skin and the muscles. 



