274 



PRACTICAL ANATOMY. 



THE BRAIN. 



The brain is the organ of the intellect and will. It 

 consists of four parts, the cerebrum, cerebellum, pons 

 Varolii, and the medulla oblongata, and is contained 

 within the cavity of the cranium. The brain weighs, in 

 the adult male, about fifty ounces ; in the adult female, 

 about forty-five ounces. It increases in weight up to the 





WHITE SUBSTANCE' 



or THE CEREBRAL HEMISPHERE 

 (FORMED OF NERVE FIBRES) 



FIG. 118. DIAGRAM OF BRAIN. 



fortieth year. After the sixtieth year it generally de- 

 creases, it is estimated, to the extent of an ounce to an 

 ounce and a half in each decade. The brain of the 

 human species is heavier than the brain of any other 

 creature except in the elephant and the whale. The 

 brain of the elephant weighs about eight pounds. 



In comparison with the bulk of the body, the brain 

 of some birds and small vertebrates is relatively larger 



