THE BRAIN. 83 



beyond it on each side, will be seen a portion 

 of the cerebellum. 



207. Remove the brain entirely from the skull cav- 

 ity, breaking away the bones as may be required. 

 Note that, on its dorsal aspect, the dura mater adheres 

 closely to it as far back as the prosencephalic lobes ex- 

 tend, and that so far there is no separate periosteum 

 for the inner surfaces of the cranial bones. Farther 

 back, on the contrary, the membrane splits into two 

 layers, one of which adheres to the bones as a thin 

 membrane while the other invests the brain as a sep- 

 arate dura mater, and between the two there is a con- 

 siderable space. 



208. Remove the dura mater, the pineal gland, and 

 the processes of the meninges which dip between the 

 main subdivisions of the brain, and study the parts of 

 the encephalon carefully (170-179). Now that it is re- 

 moved from the skull and hardened, it can be better 

 examined than before. Note: ^ 



a. The olfactory lobes {rhlnencephalon), which are 

 separated by a shallow groove from one an- 

 other and from the prosencephalon. 



b. Beginning on the dorsal side, push apart the 

 prosencephalic lobes where they lie in contact 

 in the middle line, until the optic commissure 

 comes into view ; note the absence of any 

 corpus callosum uniting them. 



c. The posterior end of each cerebral hemisphere 

 {prosencephalic lobe) is free, and diverges from 

 the median plane so as to pass outside the 

 mesencephalon, to the posterior border of 



