THE SPINAL CORD AS A CONDUCTOR 



355 



III 



I! 



IV 



VII 



VIII 



FIG. 175. Diagram of sections of the spinal cord of the monkey showing the position of 

 degenerated tracts of nerve fibres after specific lesions of the cord itself, the afferent 

 nerve roots, and of the motor region of the cerebral cortex. (SCHAFER.) (The degenera- 

 tions are shown by the method of Marchi.) The left side of the cord is at the reader's 

 left hand. 



I. Degenerations resulting from extirpation of the motor area of the cortex of the 

 left cerebral hemisphere. 



II. Degenerations produced by section of the posterior longitudinal bundles in the 

 upper part of the medulla oblongata. 



Ill and IV. Result of section of posterior roots of the first, second, and third lumbar 

 nerves on the right side. Section III is from the segment of cord between the last 

 thoracic and first lumbar roots ; section IV from the same cord in the cervical region. 



V to VIII. Degenerations resulting from (right) semi-section of the cord in the 

 upper thoracic region. V is taken a short distance above the level of section ; VI 

 higher up the cord (cervical region) ; VII a little below the level of section ; VIII 

 lumbar region. 





