362 



PHYSIOLOGY 



cerebral hemispheres are produced as two hollow pouches The 



the fore-brain to sometimes spoken of as the diencephalon wh.le the antenor pa, 



of the cerebral hemisphere growing from it is the telencephalon. The floor or rmtri 



Optic II.TVO 



Optic commissure 

 Efypophyrifl 



Anterior commissure 

 Foramen of .M<mro 



3rd n<-i-v.> 



Corpus mammilinro 

 3rd ventricle 

 Cerebral peduncle 



P ns 



Superior meduDwry velum 



I i-:. 179. Median section of an adult human brain. (J. SYMINGTON.) 



wall of the fore-brain undergoes moderate thickening to form the nervous structures 

 which occupy the ' in in peduncular space ' at the base of the brain, viz. the posterior 

 |M-rfirated spot, the corpora numimillaria and the tuber cinrivum. The roof of the 

 first coivliral vrsii-lr ivniains thin and in its primitive epithelial condition, like the roof 

 of the back part of the fourth \vntriele. 



In the course of de\ cliipinmt the ccivlnal hemispheres become larger than the 

 whole of the rest of the brain put t-.^.-t he; . growing backwards over the latter EM far 

 as tin- middle of tto cerebellum '!"!.'. IT'.M. Their donal and lateral wralb become much 



