GENERAL AND SPECIAL SENSIBILITY. 479 



rate points, but the two sensations were confounded into one. The 

 distance, however, at which the two points failed to be distinguished 

 from each other, was much shorter for some parts of the body 

 than for others. Prof. Valentin's measurements, 1 which are the 

 most varied and complete, give the following as the limits of dis- 

 tinct perception in various parts : 



PARIS LINE. 



At the tip of tongue .483 



" palmar surface of tips of fingers .... .723 



" " " of second phalanges . . . 1.558 



" " " of first phalanges .... 1.650 



" dorsum of tongue 2.500 



" dorsal surface of fingers 3.900 



" cheek 4.541 



" back of hand 6.966 



" skin of throat 8.292 



" dorsum of foot 12.525 



" skin over sternum 15.875 



" middle of back 24.208 



This method cannot, of course, give the absolute measure of the 

 acuteness of sensibility in the different regions, since the two points 

 might be less easily distinguished from each other in any one re- 

 gion, and yet the absolute amount of sensation produced might be 

 as great as in the surrounding parts ; still it is undoubtedly a very 

 accurate measure of the delicacy of tactile sensation, by which we 

 are enabled to distinguish slight inequalities in the surface of solid 

 bodies. AVe find, furthermore, that certain parts of the body are 

 particularly well adapted to exercise the function of general sen- 

 sation, not only on account of the acute sensibility of their integu- 

 ment, but also owing to their peculiar formation. Thus, in man, 

 the hands are especially well formed in this respect, owing to the 

 articulation and mobility of the fingers, by which they may be 

 adapted to the surface of solid bodies, and brought successively 

 in contact with all their irregularities and depressions. The hands 

 are therefore more especially used as organs of touch, and we are 

 thus enabled to obtain by their aid the most delicate and precise 

 information as to the texture, consistency, configuration, &c., of 

 foreign bodies. 



But the hands are not the exclusive organs of touch, even in the 

 human subject, and in some of the lower animals, the same func- 



1 In ToHd's Cyclopaedia of Anatomy and Physiology, vol. iv., article on Touch, 

 by Dr. Carpenter. 



