THE SENSE OF SMELLING. 
431 
proves that the sensibility to the acrid or stimulating gases was not 
destroyed, although the sense of smell was gone. This was put 
satisfactorily to the test. A piece of meat was rolled in paper and 
placed before the dog, but he did not take any notice of it. 
The experiment was reversed. The nasal branch of the fifth 
pair was divided in another dog. He was almost insensible to the 
substances from which the acrid gases were eliminated; but food 
well rolled in paper, was presented to him, and he unrolled the 
paper, and got at the food, and ate it, — proving most satisfactorily 
that it was the common sensibility of the part that was destroyed, 
while the olfactory nerve remaining untouched, the dog was fully 
sensible to the odour of the meat. 
I used, however, to think that there was, notwithstanding this, 
some mysterious connexion between the nerves of common and 
special sensation ; and that their agency must occasionally be com- 
bined in order to render the function of either complete. I used 
to fancy that I saw the nerves of common and peculiar sensation 
combining for the perfection of the sense of smell. The influence 
of the fibrils of common sensation on the tissue might dispose the 
nervous pulp of peculiar sensation more acutely to receive the 
impression, and to cause it to be conveyed more energetically to 
the common sensorium : but I am now disposed — at least, the parts 
being in a state of health — to doubt or to deny this; and my pre- 
sent feeling undoubtedly is, that the fifth nerve has no influence 
either on vision, hearing, or smell. The records of human medi- 
cine contain well-authenticated instances of disease of the whole 
trunk of the fifth pair, and insensibility of one side of the head, 
while vision and smell remained perfect. 
It is a singular circumstance, and illustrative of our present sub- 
ject, and shewing likewise the perfect distinctness of character be- 
tween the nerves of common and of special sensibility, that this .very 
nerve, in common with the optic nerve, may be divided without 
the animal experiencing the slightest pain, or being immediately 
conscious of the fact. For a knowledge of this we are indebted to 
Dr. Magendie. 
In my younger years, I was much associated with a gentleman 
who had been blind almost from his infancy. I used to admire how 
beautifully his other senses almost fully compensated for the loss of 
sight. I was sometimes almost incredulous as to his perfect loss of 
sight : but I did not afterwards easily pardon myself for my incre- 
dulity ; and he once gave me a striking proof of the acuteness of his 
common sensation. I did not mean to hurt him, but I wanted to 
try whether I could not lead him plump against a loaded waggon 
that was standing in our road. Ere he was within six feet of it, I 
had a rap on my pericranium, which I richly deserved, and did not 
