DR. MARSHALL HALL. 
619 
“You observe this living frog. Its sentient and voluntary 
functions are obvious. I will divide the spinal marrow below 
the occiput with these scissors: — all is still. There is not a trace 
of spontaneous motion. The animal would remain in this very 
form and position, without change, until all signs of vitality were 
extinct. But now I pinch a toe with the forceps. You see how 
both posterior extremities are moved. All is now still again ; 
there is no spontaneous motion, no sign of pain from the wound 
made in the neck. It is without sensibility — without volition ; 
the power to move remains — the will is extinct. I now pinch 
the integument. You observe the result — the immediate recur- 
rence of excito-motory phenomena. — I now destroy the whole 
spinal marrow with this probe. It is in vain that I pinch the 
toes : the animal, the limbs, are motionless. — Could the former 
excited motions be those of irritability 1 I will try the truth of 
this suggestion, by seeing whether, now that the axis of the ex- 
cito-motory system (the spinal marrow) is destroyed, with its 
phenomena, the application of a slight galvanic shock will prove 
the subsistence of irritability. You see how instantaneously and 
forcibly the muscles are stimulated to contraction. Is not the 
proof from these experiments, of the distinction between the mo- 
tions of volition of the excito-motory system, and of those of 
irritability, perfectly and unequivocally complete V* 
The amount of knowledge we derive through this experiment, 
supposing the deductions of the Doctor to be legitimate, is, indeed, 
of the utmost value to us both in a physiological and pathological 
point of view : we now know — or appear to know — that there 
exist three kinds of nervous power or influences,— a cerebral, 
a spinal, and a purely nervous or ganglionic one; and that these 
may not be supposed to reside only in inferior, but also pervade 
the superior animals, the Doctor made the following experiment 
on a horse : — 
“A horse was struck with the poll-axe over the anterior lobes 
of the brain. It fell instantly, as if struck with a thunderbolt : 
it was convulsed, and then remained motionless. It shortly be- 
gan to breathe, and continued to breathe freely by the dia- 
phragm. When lacerated or pricked by a sharp or pointed in- 
strument, as a pin or a nail , on any part of the face or surface of 
the body, it was totally motionless, manifesting no evidence of 
sensation or volition. When, on the other hand, the eyelash was 
touched with a straw, the eyelid was forcibly closed by the action 
of the orbicularis. When the cornea was touched, the eyeball 
revolved outwards by the action of the abducens. When the verge 
of the anus was touched, the sphincter contracted forcibly, the 
tail was raised and the vulva was drawn towards the anus. The 
