CHAPTER III 



The nervous system of the Star-fish Purposive move- 

 ments dependent on presence of sensory organs 

 Development of head in animals Earth-worms 

 Rudimentary brain Hereditary instinctive move- 

 ments Crayfish Increased complexity of brain 

 corresponding to higher order of instinctive move- 

 ments Labyrinth experiments The brain of 

 insects Their sensory organs Highly developed 

 instinctive processes in Ants, etc. Automatic 

 processes. 



IN the preceding chapters we have endeavoured 

 to show that some of the elements of living 

 protoplasm possess a special aptitude for 

 becoming adapted to the incidence of recurring 

 modes of energy; in this way the sensory and 

 nervous structures of the ascending classes of 

 animals have become moulded on a uniform 

 plan. The changes in structure thus effected 

 have led to corresponding modifications in the 

 work which these structures perform, the move- 

 ments of the advancing orders of animals thus 



