the voluntary muscles with the brain. 169 



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 



MDCCCXXVI. Z 



