412 Mr. Bell's experiments on the structure 
neck, are connected with branches of the spinal nerves, and 
with the respiratory nerves, as may be seen in the adjoined 
plate. 
Its structure. 
When we minutely observe the texture of the respiratory 
nerve of the face, we find it to correspond with the structure 
of the par vagum, and to differ from that of the trigeminus. 
The filaments of this nerve have a very close texture, like a 
minute plexus. The fifth, compared to it, has large free 
round filaments, with less intricacy in their texture. 
If we were barely to consider this distribution of the portio 
dura of the seventh, unbiassed by theory or opinion, we should 
be forced to conclude, that it is not alone sufficient to supply 
any one part with nervous power, for every one of its 
branches is joined by divisions of the fifth. The question 
then naturally arises, whether these nerves perform the same 
function ? whether they furnish a double supply of the same 
property or endowment, or whether they do not perform 
different offices ? having taken all the assistance that the 
knowledge of the human structure and comparative anatomy 
afford, we are prepared to decide the matter by experiment. 
Experiments on the nerves of the face. 
An ass being thrown, and its nostrils confined for a few 
seconds, so as to make it pant and forcibly dilate the nostrils 
at each inspiration, the portio dura was divided on one side 
of the head ; the motion of the nostril of the same side in- 
stantly ceased, while the other nostril continued to expand 
and contract in unison with the motions of the chest. 
On the division of the nerve, the animal gave no sign of 
