THE NERVOUS SYSTEM. 143 



CHAPTER IX. 

 THE NERVOUS SYSTEM. 



SECTION I. 1, An injury to the head, if violent 

 enough, will kill at once. If less violent, it will stun the 

 victim. He will drop, limp and helpless, and will know 

 nothing for a time; but his heart will continue to beat 

 feebly, and he will still breathe. In time he will get his 

 senses, and his power over his muscles again. 



2, An injury to the backbone, if violent enough, will 

 paralyze the lower limbs. The man is not stunned ; and 

 he breathes, and his heart beats. He can move with all 

 the muscles above the injury: but those below are useless, 

 though they have not been hurt ; and perhaps he will have 

 no feeling in those parts. In the case of the injury on 

 the head, the part that is hurt is the brain. In the case 

 of the injury on the back, the part that is hurt is the 

 spinal cord. 



3, The brain fills the chief cavity of the skull. It is 

 not one mass, but several masses joined together. The 

 largest mass is called the cerebrum. The next in size is 

 the cerebellum (little brain), which lies behind and beneath 

 the cerebrum. The pom Varolii is a mass in front of the 

 cerebellum and beneath the cerebrum. The medulla 

 oblongata is beneath the cerebellum, and behind the pons 

 Varolii. 



SUGGESTION TO TEACHERS. SECTION I. 3. Get a sheep's or calfs brain. 

 The chief divisions, the convolutions, and the gray and white matter, can be 

 shown. 



