4 66 TEXT-BOOK OF PHYSIOLOGY. 



in the gray matter; the pathway for tactile impressions has been 

 located in the posterior columns, though this is not beyond dispute. 

 The pathway for pain sensations has been located in Powers' t ra r*- * 



The relation of the motor and sensor pathways to each other in 

 the spinal cord and brain are shown in Plate II. The afferent fibers 

 which decussate at various levels through the spinal cord are not 

 represented. 



