THE- NERVOUS SYSTEM. 



153 



with the convolutions unfolded, is'cornputed to be equal to 

 four square feet; and yet it is easily enclosed within the 

 narrow limits of the 

 skull. When it is 

 stated that the gray 

 matter is the' true 

 source of nervous 

 power, it becomes 

 evident that this 

 arrangement has an 

 important bearing 

 on the mental ca- 

 pacity of the indi- 

 vidual. And it is 

 noticed that in 

 children, before the 

 mind is brought 

 into vigorous use, 

 these markings or 

 furrows on the sur- 

 face are compara- 

 tively shallow and 

 indistinct; the same fact is true of the brain in the less 

 civilized races of mankind and in the lower animals. It is 

 also noticeable, that among animals, those are the most 

 capable of being educated which have the best develop- 

 ment of the cerebrum. 



10. The Cerebellum. The "little brain" is placed 

 beneath the posterior part of the cerebrum, and, like the 

 latter, is divided into hemispheres. Like it, also, the sur- 

 face of the cerebellum is composed of gray matter, and its 

 interior is chiefly white matter. It has, however, no con- 

 volutions, but is subdivided by many crescentic, parallel 

 ridges, which, sending down gray matter deeply into the 



-II. Ui'PKK SURFACE OF THE CEREBRUM. 



A, Longitudinal Fissure. 



B, The Hemispheres. 



10. Location of the " little brain ?' 

 Its subdivisions ? Its size ? 



How divided ? Its surface and interior ? 



7* 



