NERVE CENTERS 509 



exceedingly complex system of communicating fibers. The cerebro-spinal 

 axis may in fact be regarded as a segmental chain of nerve centers, the com- 

 plexity increasing from the cord toward the brain, and the coordinating con- 

 trol culminating in the cerebral cortex. 



FIG. 357. 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 membranes 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.) 



