STUDY OF BRAIN OF SHEEP. 93 



2. Is it divided into two parts like the fore- 



brain ? 



3. What is the appearance of its outer surface? 



(Compare with the surface of the cerebral 

 hemispheres.) 



4. In the section of the cerebellum describe 



the distribution of gray and white mat- 

 ter. 



5. On the ventral surface of the hind-brain, 



just beneath the cerebellum, note a band 

 of white matter (the pons = bridge) con- 

 necting the lateral portions of the cere- 

 bellum. Does the pons, therefore, run 

 crosswise or lengthwise of the brain? 



6. The rest of the hind-brain is called the me- 



dulla (or medulla oblongata) . Name and 

 locate, now, each of the three regions of 

 the hind-brain. 



7. The portion of the nervous system which 



forms a posterior continuation of the 

 medulla is the spinal cord. What is the 

 general shape of the cord? Describe its 

 cross section. Can you distinguish gray 

 and white matter? If so, locate each. 

 D. Mid-brain. 



i. Carefully bend the brain near the middle 

 in such a way as to enable you to look 

 down between the cerebral hemispheres 

 and the cerebellum. This connecting 

 isthmus is the mid -brain. Describe its 

 position with reference to fore- and hind- 

 brain. 



