204 BIOLOGY FOR BEGINNERS 



General tendency of nervous development: 



1. Fewer ganglia. 



2. Increasing complexity (centralizing control). 



3. Location in anterior (first contact with environment). 



General functions of nervous system. 



1. To receive impressions from without (sensation). 



2. To control and originate motion (motor impulses). 



Life History: 



1. Kgg, fertilized, buried in earth by ovipositors. 



20-30 in two masses, in autumn. 



Functions: to reproduce and to pass winter protected. 



2. Nymph, like adult but small and wingless. 



Growth by moults, development of wings. 



Complete and incomplete metamorphosis compared. 

 Economic Importance. 



