408 BIOLOGY. [Book vi. 



on the palmary and plantary faces of the hand and foot of man, 

 where, by their juxtaposition, they trace curved lines, crowded 

 and i-egular. On the palmary face of the ungual joint of the 

 forefinger, Meissner counted eight hundred corpuscles of touch 

 in the space of a square line. 



These corpuscles are of ovoid form, and each of them is 

 constituted by a dermic bed, covering a small mass of conjunc- 

 tive tissue. A sensitive nervous cord penetrates the corpuscle 

 at its base. It is certain that these tactile corpuscles are 

 apparatus which reinforce sensation, but are not indispensable 

 to it. The different tactile sensations are still experienced by 

 the skin in the regions where the corpuscles are wanting, but 

 much less clearly. The internal surfaces of the terminal joints 

 of the fingers, for example, feel the two points of a compass at 

 a distance of Seven-tenths of a line, while on the level of the 

 dorsal spine a distance of twenty-four lines is required to keep 

 the two sensations from being confounded.^ At the tip of the 

 tongue, on the contrary, the two sensations are still received at a 

 distance of half a line. 



1 E. J. "Weber, De SuUilitate Tadus, in the work entitled : De Pulsu, 

 Besorptione, Auditu, et Taetu. Annotationes Anat. et Physiol., Lipsiae, 1834. 



