56 NERVOUS SYSTEM. 



commencement of asphyxia. Some have endeavored to ex- 

 press this difference by applying to the latter form of sensa- 

 tion the name of sentiment, and reserving for the former that 

 of sensation properly speaking. But a similar influence may 

 give rise at the same time to a general localized sefisation and 

 a vague sensation or sentiment. Thus it is that hunger is 

 manifested by a sensation that we localize at the epigastrium 

 (stomach), and also by a vague and indefinite sentiment that 

 is experienced throughout the organism and which spreads to 

 the extremities in the form of fatigue. The same is true 

 concerning thirst, which sensation is referred to the throat and 

 also to a general sentiment of languor. 



The general non-localized sensations are a very interesting 

 study for the physician ; one of the most curious of these in 

 the light of its pathological modifications is the sentiment of 

 our existence ; this sensation passes ordinarily unnoticed, 

 because it is habitual and constant ; it is pretty much the 

 same as with the miller who does not notice the noise of his 

 mill. When this sensation is noticed it indicates usually a 

 pathological condition whose seat is most generally in the 

 cerebro-spinal centre (hypersesthesia), and makes us expe- 

 rience to a painful degree all the phenomena going on in our 

 organism ; this feeling of habitual malaise constitutes hypo- 

 chondria. 



Localized sensations are ordinarily produced under the 

 influence of an external action on some definite portion of 

 the surface of the body, and are conveyed to the nerve-cen- 

 tres by means of nerves which are always definitely deter- 

 mined. But should some cause act upon these nerves in any 

 portion of their extent, we perceive the sensation which occurs, 

 just as if the action were brought to bear upon the point 

 where these nerves originate. If, for instance, the ulnar nerve 

 is suddenly compressed at the posterior portion of the elbow 

 on its inner aspect (epitrochleo-olecranon groove, or groove 

 near the inner condyle of the humerus), we localize the pain- 

 ful impression so caused at the cutaneous extremity of this 

 nerve, or, in other words, at the inside of the hand (and espe- 

 cially in the little finger). This phenomenon constitutes what 

 is called the eccentricity of the sensations / whatever may 

 be the point where the nerve is attacked, the sensation inva- 

 riably is eccentric ; even when the central portion is attacked 

 we localize the sensation at the peripheral end of the sensitive 

 nerve in question. Patients struck down by cerebral apoplexy 

 complain of peripheral pains whose cause is wholly central. 



