180 MOVEMENTS OF DEGLUTITION. 
be even made to take place against the will. This may seem | 
contrary to every one’s daily experience ; but it is nevertheless 
true. The movement by which the food is carried back, | 
beneath the arch of the palate, into the pharynx, is effected by 
the will ; but when the food has arrived there, it is laid hold of, — 
as it were, by the muscles of the pharynx, and is then carried — 
down involuntarily. It has several times happened, that a 
feather, with which the back of the mouth was beitig tickled — 
to excite vomiting, having been introduced rather too far, has 
been thus grasped by the pharynx, and has been swallowed. — 
Moreover, we cannot perform the act of swallowing, without 
carrying something backwards upon the tongue ; and it is the © 
contact of this something, even if it be only a little saliva, 
with the membrane lining the pharynx, that produces the — 
muscular movement in question. 
195. This action is one of the kind now denominated reflex 
(§ 430). It is produced through the nervous system ; for if 
the nerves supplying the part be divided, it will not take 
place. But it does not depend upon the Brain; for it may 
be performed after the brain has been removed, or when its 
power has been destroyed by a blow. It is caused by the 
conveyance to the top of the Spinal Cord, of the impression 
made on the lining of the pharynx ; this impression, brought 
thither through one set of nerves, excites in the spinal cord a 
motor impulse; which, being transmitted thence through 
another set of nerves, calls the muscles into action. 
196. This action is, therefore, necessarily connected with 
the impression, so long as this portion of the spinal cord, and 
the nerves proceeding from it, are capable of performing their 
functions : and it is one of those to which we may give the 
name of instinctive, to distinguish it from those which are 
effected by an effort of the Will, intentionally directed to 
accomplish a certain purpose. It may even take place without 
the animal being aware of the contact of any substance to be. 
swallowed with the lining of the pharynx ; for there is good | 
reason to believe that when the brain has ‘been destroyed, or 
paralyzed by a blow, all sensibility is destroyed ; and we have 
also sufficient reason to consider it as suspended in profound 
sleep or apoplexy, in which states swallowing is still per-_| 
formed. In the severest cases of apoplexy, however, th 
power of swallowing is lost; and this is a symptom of g 
/ 
