TOUCH 



247 



THE SENSE ORGANS OF THE SKIN 



Touch. Of the four senses of the skin, touch alone 

 has a relatively simple mechanism. It consists of spe- 

 cial nerve endings, many of which are located within 

 rounded elongated masses called touch corpuscles. Each 

 touch corpuscle is made up of a large number of layers, 

 somewhat after the 

 fashion of an onion, 

 within which are the 

 terminal branches of 

 the nerve. It is about 

 one-twelfth of an 

 inch in length and 

 one twenty-fourth of 

 an inch in diameter, 

 and so very elastic 

 that the slightest 

 touch tends to change 

 its form. The touch 

 corpuscles are found 

 all over the body in 

 the papillae of the dermis and are especially numerous on 

 the palms of the hands, on the soles of the feet and on 

 the tongue. 



The touch corpuscles are not the only terminal organs 

 of the sense of touch. Where there are hairs, for ex- 

 ample, the touch corpuscles are much less frequent, 

 since the hairs themselves serve to transmit 'pressure 

 to the ends of the nerves, the branches of which sur- 

 round their roots. It has been estimated that there are 

 500,000 points sensitive to touch, including the hairs 

 and the touch corpuscles, scattered over the body's sur- 

 face. In addition, smaller bodies very similar to the 



FIG. 132. Section of skin showing two papillae 

 of dermis and some deeper cellt of epidermis. 

 At left side are nerve fibres leading to cor- 

 puscle. 



