434 THE NERVOUS SYSTEM IN THE LOWEK ANIMALS 



development seen in the vertebrates lower than man. 

 The featm-e which strikes the eye as most vital in this 



FROG 



Fig. 203 — A comparison of vertebrate brains; O.L. olfactory lobes; C.B., cere- 

 bral bemisplieres; Q.L. optic lobes; C,L. cerebellum; il/, medulla; S.C. spinal 

 cord. 



comparison is that the changes have arisen mainly in 

 order to accommodate the increasing brain suiface to the 

 limits of the inclosing cavities. For example, in the 



A B 



Fig. 204 — Comparative wrinkling of cerebral surface of cat (A), and man (.8). 



