NERVE CENTERS 579 



It is by means of the nerve centers that the activities of the differentiated 

 parts of the human body are brought into intimate correlation. The nerve 

 centers exercise their influence through the power of inhibiting or decreasing 

 activity; or, on the other hand, of augmenting or increasing the activity in the 



FIG. 359. View of the Cerebro-spinal Axis of the Nervous System. The right half of 

 the cranium and trunk of the body has been removed by a vertical section; the mem- 

 branes of the brain and spinal cord have also been removed, and the roots and first part of 

 the fifth and ninth cranial, and of all spinal nerves of the right side, have been dissected 

 out and laid separately on the wall of the skull and on the several vertebrae opposite to the 

 place of their natural exit from the cranio-spinal cavity. (After Bourgery.) 



