THE NERVOUS SYSTEM. 99 



(2) Its structure. Are there any convolutions 



and fissures ? Is it divided into hemi- 

 spheres ? 



(3) Its relative size. Compare with the 



human brain. 

 2. The medulla oblongata, or spinal bulb. 



(1) Its shape. Raise the cerebellum, push it 



gently forward, and remove the thin 

 epithelial covering from the dorsal side 

 of the medulla. 



(2) The fourth ventricle is the chamber in the 



medulla. What is its shape ? Where 

 does it open posteriorly? 



(3) The diverging posterior columns, or pyramids, 



are on either side of the fourth ven- 

 tricle. 



(4) The restiform bodies, a rounded eminence 



in each column. Anteriorly find where 

 they pass into the inferior peduncles of 

 the cerebellum. 



(5) The superior peduncles of the cerebellum, 



one on each side, proceed from the 

 cerebellum and pass beneath the poste- 

 rior corpus quadrigeminum of the same 

 side. 



(6) On the under, or ventral, surface of the 



medulla notice two cords, the anterior 

 pyramids. Compare them with the pos- 

 terior pyramids. 



(7) The pons Varolii. In which direction do 



its fibres run? Follow its fibres on 



