486 On the Nervous Systems of 
b. Neither is sensation cxcited by an impression 
made upon a part, the nerves of which are con 
nected with the spinal marrow, if the -spinak 
marrow be divided, or strongly compressed, 
above the point, where these nerves are joined 
to it. Hence it is equally proved, that the 
spinal marrow below its junction with the brain 
is not the seat of sensation. 
c. If the whole of the nerves of a limb, or any 
part, be divided, or so strongly compressed, as 
to intercept all communication betwixt the limb 
or part, and the brain, no motion can be excited in 
the former by volition: Consequently the power 
of beginning voluntary motion is not in the nerves. 
d. If the spinal marrow be divided, or strongly 
compressed, in the neck or any lower point, none 
of the parts, supplied with nerves from the spinal 
marrow below the injured part, can be excited to 
action by the will. Hence it is proved, that the 
power of beginning voluntary motion is not resi- 
dent in the spinal marrow. 
e. When the spinal marrow is injured in the 
manner just mentioned,, the mental faculties are 
not necessarily impaired, and. sensation may be 
excited and voluntary motion produced in those 
parts, which are supplied with nerves from .the 
_ brain, or from the spinal marrow, above the in 
-jured part. Hence it is demonstrated, that the 
brain, or the junction of this with the spinal mar- 
