388 SENSATION IN GENERAL. 
monly refer our various sensations to the parts at which the — 
impressions are made,—as, for instance, when we say that we 
have a pain in the hand, or an ache in the leg,—we really 
use incorrect language ; for, though we may refer our sensa-— 
tions to the points where the impression was made on the 
nerve, they are really felt in the brain. This is evident from 
two facts; first, that if the nervous communication of the — 
part with the brain be interrupted, no impressions, however 
violent, can make themselves felt ; and, second, that if the 
trunk of the nerve be irritated or pinched anywhere in its 
course, the pain which is felt is referred, not to the point 
injured, but to the surface to which these nerves are distri-— 
buted. Hence the well-known fact that, for some time after — 
the amputation of a limb, the patient feels pains which he 
. refers to the fingers or toes that have been removed ; this con- 
tinues until the irritation of the cut extremities of the nervous — 
trunks has subsided. q 
487. Among the lower tribes of Animals, it would seem 
probable that there is no other kind of sensibility than 
that which is termed general or common, and which exists, in 
a greater or less degree, in almost every part of the bodies of 
the higher. It is by this that we feel those impressions, | 
made upon our bodies by the objects around us, or by actions 
taking place within, which produce the various modifications 
of pain, the sense of contact or resistance, the sense of varia- 
tions of temperature, and others of a similar character. From 
what was formerly stated (§ 63) of the dependence of im: 
pressions made on the sensory nerves upon the action of the 
blood-vessels, it is obvious that no parts destitute of the latter 
can receive such impressions, or (in common language) cam 
possess sensibility. Accordingly we find that the hair, nails, | 
teeth, tendons, ligaments, fibrous membranes, cartilages, and 
bones, whose substance either contains no vessels, or but ver’ 
few, are either completely incapable of receiving painful 
impressions, or have but very dull sensibility to them. Or 4 
the other hand, the skin and other parts which usually receive 
such impressions, are extremely vascular; and it is interesting — 
to observe that some of the tissues just mentioned, when new 
vessels form in them in consequence of diseased action, 
become acutely sensible. It does not necessarily follow, how- § 
ever, that parts should be sensible in a degree proportional to — 
aie 
