CHAPTER XXII. 

 THE BRAIN. 



The Coverings of the Brain. There are two coats of 

 the brain, the dura mater, a tough membrane, adhering to 

 the inside of the skull; and the pia mater, next to the 

 brain, a much thinner membrane, traversed by blood 

 tubes, and dipping down into the grooves between the 

 convolutions of the cerebrum. 



The Parts of the Brain. The parts of the brain are the 

 cerebrum, the cerebellum, and the spinal bulb. 



The Cerebrum. The cerebrum consists of two lateral 

 hemispheres, separated by a deep groove in the middle 

 line. The surface of the cerebrum is in irregular ridges, 

 the convolutions. The outside of the brain consists of 

 gray matter. The inner part of the brain is white, and 

 the two halves are connected by a broad band which con- 

 sists of many white fibers. 



The Cerebellum. Back of, and below the cerebrum is 

 the cerebellum. It is much smaller than the cerebrum, 

 and has fine transverse ridges and grooves in place of the 

 convolutions of the cerebrum. It is also of a deeper color, 

 a reddish gray. 



The Spinal Bulb. The enlarged beginning of the 

 spinal cord is the spinal bulb. It is white, like the rest of 

 the cord. 



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