SIR CHARLES BELL. 271 



tends " that the cerebrum and the cerebellum are 

 different in function as in form ; that the parts of 

 the cerebrum have different functions ; and that the 

 nerves which we trace in the body are not single 

 nerves, possessing various powers, but bundles of dif- 

 ferent nerves, whose filaments are united for the con- 

 venience of distribution, yet are distinct in office, as 

 they are in origin from the brain." 



In speaking of the nerves springing from the 

 spinal cord, Mr. Bell says that the anterior column 

 presides over the motor functions, and the posterior 

 column sends out sensory nerves having ganglia upon 

 them ; and that often the two sets from one side of 

 the cord have united in one bundle ; both motor and 

 sensory filaments can be traced to the periphery of the 

 body, where they may be said to be distributed. 



Before Bell's discoveries it was supposed that the 

 nerves of special sense, as the optic, for instance, could 

 bestow sensation or pain, or even motion, as well as 

 vision. A careful dissection of the nerves of the face 

 aiad head revealed the origin and distribution of sen- 

 sory and motor filaments ; and experiments upon ani- 

 mals clearly proved what was the function of any 

 given nerve. Bell demonstrated that the sixth and 

 ninth pairs of cranial nerves were exclusively motor 

 the one going to the external rectus of the eyeball^ 

 and the other to the deep parts of the tongue to the 

 muscles of the organ, and having nothing to do with 

 the sense of taste. In studying the fifth pair the 

 trifacial he found on each side of the median line 

 two nerves, one, the larger, having a ganglion upon it, 

 and the other, the smaller, without a knot, and like a 

 motor nerve coming from the anterior columns of the 

 cord. The large trunk, having a ganglion upon it, he 



