v SPINAL CORD AND NEKVES 345 



persistence of tactile sensibility, while sensibility to pain is wholly 

 abolished. 



(c) The converse experiment, that is section of the posterior 

 columns only, while the rest of the spinal cord is left intact, pro- 

 duces immediate and permanent loss of tactile sensibility, while 

 pain sensibility persists. 



(d) Section of the ventro-lateral columns does not abolish 

 tactile or pain sensibility. 



(e) Two lateral hemisections, right and left, at different levels, 



FIG. 192. Section of ventral and thoracic columns with nearly the whole of the grey matter in 

 rabbit level of last dorsal vertebra. (Woroschiloft'.) 



at a certain distance from one another, reduce sensibility to pain 

 on both sides, while tactile sensibility is entirely abolished. 



(/) Median longitudinal section of the lumbar cord at the 

 level at which the nerves to the lower extremities pass out, 

 diminishes sensibility to pain, while tactile sensibility and motility 

 remain intact. 



From these experiments Schiff formulated the following 

 theoretical conclusions : Tactile sensibility is carried to the brain 

 by the fibres of the dorsal columns on the same side, which, there- 

 fore, do not cross in the cord ; pain sensibility is transmitted by 

 the grey matter of both sides, but chiefly through the opposite 

 side ; motor impulses are transmitted by the grey matter and by 

 the ventro-lateral columns; the ventro-lateral columns do not 

 transmit sensory impressions. 



