THE NERVOUS SYSTEM. 109 



into these dividing lines, so that the two surfaces of the 

 gray matter are in contact. The quantity of gray matter in 

 the brain is the true measure of brain power. Not only 

 does the depth of the folds vary in different brains, but also 

 the thickness of the gray matter. To ascertain, therefore, 

 the extent and amount of gray matter, it would be necessary 

 to open out the convoluted mass and measure its thickness. 

 In view of these facts, the value of phrenology, as practised 

 by bump-feelers, may be duly estimated. To define a per- 

 son's character and mental ability by the outward appearance 

 of the skull is impossible. In order to arrive at a correct 

 estimate, it would be necessary to know the thickness of the 

 skull, the depth of the frontal space, x he thickness of the 

 gray matter, and the depth to which the layer dips down 

 between the convolutions. 



3. Function of the Gray Matter of the Brain. The 

 gray matter of the brain is the seat of the will. Here, in a 

 measure, is generated the nerve force. It is the seat of the 

 intellectual faculties, the throne of reason. At this seat of 

 power resides the authority by which the body is governed. 

 Messages are continually arriving in the brain from every 

 part of the body, far and near, regarding the welfare of the 

 several parts or dependencies. At these headquarters due 

 notice is taken of everything concerning its welfare, and 

 orders are issued to muscles and other tissues, by which the 

 interests of the body are looked after. The gray matter is 

 made up of minute cells and of vascular tissue. 



4. Function of the White Matter of the Brain. 

 The white fibrous matter upon which the gray is laid receives 

 the directions and instructions from the seat of power, and by 

 white cords laid to every part of the frame, like telegraph 

 wires, transmits the nervous influence to whatever part of the 

 body it may be necessary. By the same nerve wires, intel- 

 ligence is received from every station in the body, even the 



