THE NEKVOUS SYSTEM. 173 



pared with the weight of the body, does not, in all instan- 

 ces, exceed that of the inferior animals; the canary and 

 other singing-birds have a greater relative amount of nerv- 

 ous matter than man ; bnt man surpasses all other crea- 

 tures in the size of the hemispheres of the cerebrum, and 

 .in the amount of gray substance which they contain. 



54. It is a singular fact that this cerebral substance is 

 insensitive, and may be cut without causing pain. The 

 removal of a considerable quantity of the brain has taken 

 place, as the result of accident, without causing death, and 

 without even affecting seriously the intellect. A remark- 

 able case of injury of the brain is recorded, in which, 

 from the accidental explosion of gunpowder used in blast- 

 ing a rock, the " tamping-iron" was driven directly through 

 the skull of a man. This iron rod, three feet and seven 

 inches long, an inch and a quarter in diameter, and weigh- 

 ing more than thirteen pounds, entered the head below the 

 ear and passed out at the top of the skull, carrying with it 

 portions of the brain and fragments of bone. The man 

 sustained the loss of sight on one side, but otherwise 

 recovered his health and the use of his faculties. More- 

 over, disease has occurred, compromising a large portion 

 of the brain, without impairing the faculties of the mind, 

 when the disease was limited to one side only. 



55. Impressions conveyed to the hemispheres from the 

 external world arouse the mental operations called 

 thought, emotion, and the will. These are the god- 

 like attributes which enable man to subjugate a world, 

 and afterward cause him to " sigh for other worlds to con- 

 quer;" which enable him to acquaint himself with the 

 properties of planets millions of miles distant from him, 

 and which give him that creative power by which he 

 Guilds and peoples the new worlds of poetry and art. 



54. Sensitiveness of the brain substance? The removal of a portion of the 

 train ? State the remarkable case mentioned ? 



55. Thought, emotion, and will ? What power do they give us ? 



