THE GREAT SPINAL ORGANIC NERVE. 
59 
a voluntary nerve. If the lingual nerve is divided, all the motions 
of the tongue connected with deglutition cease, and the food placed 
on the dorsum of it will remain there, in. spite of every effort of the 
muscles of the pharynx ; but by this excito-motory power, wisely 
and kindly given to the more important nerves of organic life, 
the voluntary muscles of the tongue were summoned to the as- 
sistance of the organic ones of the pharynx, before the will had 
any influence over them ; and they still continue to act, not in 
defiance of the will, but independent cf its commands. 
Let it also be recollected that these branches of the great 
spinal organic nerve are beginning to discharge here, what they 
do more perfectly in other parts, the functions of a sensitive as 
well as a motor nerve. They preside over the organic sensibi- 
bility of the mucous membranes, as much as over the action of 
the various muscles, and there are sufficient anastomoses very 
soon to connect with these the sensibilities of animal life also. 
These are considerations of which the student should have a 
clear conception. The sensibilities of the organic nerves is the 
capability of receiving impression from the various substances, 
solids, fluids, and even the minutest molecules which come 
in contact with them ; — it is the principle of irritability . The 
different organs re-act upon these agents or substances, and 
arrest them, and work upon them, and transform them, as the 
purposes of life may require — this is the operation of the princi- 
ple of contractility ; but no knowledge of the impression or 
the re-action is conveyed to the sensorium. It is conveyed to 
certain masses or ganglions, which preside over these acts of or- 
ganic life, and direct them to useful purposes, and have the 
power, if need be, of calling to their aid the assistance of other 
nerves connected with the will. But we must proceed. 
The superior Laryngeal Nerve . — At a very short distance from 
the pharyngeal branch, another is sent off, which takes its course 
behind the carotid artery, and in front of the lower extremity of 
the superior cervical ganglion. It communicates with this gang- 
lion, for the purpose of carrying its secretive and nutritive in- 
fluence to the important part to which it is directed. It commu- 
nicates also with a branch of the lingual nerve, connecting with 
the functions of the larynx the action of the tongue, both volun- 
tary and by means of the excito-motory system, and without the 
command of the will. As this branch pursues its course, it passes 
over one of the pharyngeal muscles, thus connecting — and a most 
important connexion it is — the functions of the pharynx with 
that of the larynx. We see the advantage of this in the voice of 
those animals in whom it is capable of much varied intona- 
