THE REASON WHY. 243 



" The works of the Lord are great, sought out of all them that have pleasure 

 therein." PSALM cxi. 



1005. In what parts of tlie lody does the sense of touch 

 wore especially reside ? 



In the points of the fingers and in the tongue. By laying a 

 piece of paper upon a table, and upon the paper a piece of cloth, on 

 the piece of cloth a bit of silk, and on the bit of silk a piece of 

 leather, so that the edge of each would be exposed to the extent of 

 half-an-inch, it would be possible by the touch to tell when the 

 finger passed successively over the leather, silk, cloth, or paper, and 

 arrived on the table. 



Those impressions of touch must have been communicated, with 

 their extremely nice distinctions, to the sensitive nerves that lie 

 underneath the skin, and must have been transmitted all the way 

 through the arm to the brain, although the touch itself was so 

 light as scarcely to be appreciable with regard to the force applied. 



A hair lying on the tongue will be plainly perceptible to the touch 

 of the tongue ; and the surface of a broken tooth will often causes 

 the tongue great annoyance, by the acute perception it imparts 

 of the roughness of its surface. 



The toes are also highly sensitive, though their powers of touch 

 are seldom fully developed. Persons who have lost their arms, how- 

 ever, have brought their feet to be almost as sensitive as fingers. 

 Blind persons increase, by constant exercise, their powers of touch 

 to such a degree that they are able to read freely by passing their 

 fingers over embossed printing ; and they have been known to 

 distinguish colours by differences in their grain, quite unappreciable 

 by other persons. 



1006. Why is feeling impaired ivhen the Tiands are cold? 



*J / / x 



Because, as the blood flows slowly to the nerves, they are less 

 capable of that perception of touch which is their special sense. The 

 skin contracts upon the nervous filaments, and impairs the contact 

 between them and the bodies which they touch. 



1007. WTiy do the fingers prick and sting when they again 

 become warm ? 



Because, as the warmth expands the cuticle, and the blood begins 

 to flow more freely through the vessels, the nerves are made 

 conscious of the movements of the blood, and continue to be so 

 until the circulation is equally restored to all the parts. 



