169 
the voluntary muscles with the brain. 
as decisive when we apply the irritants to the extremities of 
the divided nerves which are connected with the brain ; for 
all the muscular nerves receive more or less minute filaments 
of sensitive nerves, and these we can trace into them by the 
knife, and consequently, they will indicate a certain degree of 
sensibility when hurt. To expose these nerves near their 
origins, and before any filament of a sensitive nerve mingles 
with them, requires the operator to cut deep, to break up the 
bones, and to divide the blood-vessels. All such experiments 
are much better omitted ; they never can lead to satisfactory 
conclusions. 
Experience on the human subject most abundantly illus- 
trates these facts. For example : — a patient of mine having, 
by a tumour pressing the nerves of the orbit, lost the sensi- 
bility of the eye and eye-lids, she retained the motion of the 
eye-lids by the portio dura coming round externally and 
escaping the pressure which injured the other nerves. Here 
the course of sensibility backwards to the brain was cut off, 
while the course of volition was free ; she could not tell 
whether the eye-lid was open or shut, but being asked to 
shut the eye which was already closed, she acted with the 
orbicular muscle and puckered the eye-lids. When I touched 
the eye there was no winking, because the sensitive fifth pair 
had lost its power, although she could command the motion 
by voluntary exertion. 
In another instance, when the eye was insensible, touching 
the eye gave rise to a blush of redness and to inflammation, 
because the part was excited, but the muscles were not called 
into action : the relations which connect the sensibility of the 
eye with the motions of the eye and eyelid are established 
Z 
MDCCCXXVI. 
