88 



CONSCIOUS NERVOUS OPERATIONS 



.V 



Fig. 51. Touch 

 corpuscle in pa- 

 pilla of the skin 

 of the hand. 



C touch corpuscle. 



N nerve fibers 

 winding around 

 the corpuscle. 



which receives a nerve whose fibers wind round and 

 round the capsule before entering it (Fig. 51). Still 

 smaller end bulbs are found in the skin, 

 made up of nerve fibers ending in corpus- 

 cles in which the axis cylinder of the nerve 

 terminates. All the tactile end organs are 

 covered by the epidermis, so that the nerves 

 themselves are not brought into actual 

 contact with the external thing which they 

 feel. If the cuticle were stripped off arid 

 pressure applied to a naked nerve end- 

 ing, there would be, not a sense of touch 

 with ability to judge of the properties of 

 the body causing the sensation, but in- 

 stead a sense of pain. Certain portions 

 of the skin are more fully supplied with 

 end organs for touch than are others, and the epidermis 

 there is thinner, so that the sense of touch is more deli- 

 cate. The tip of the tongue, the skin of the face, and 

 the ends of the fingers are most sensitive. A pair of 

 blunt-pointed compasses applied to the end of the tongue 

 will be distinguished as two points even when they are 

 separated by only one twenty-fourth of an inch, while 

 they would be felt as but one point on the finger ; and 

 on the arm or back of the hand the two points much 

 further apart would seem but one. 



116. Sensations of Heat and Cold. Sensations of touch 

 arise from pressure, but through the skin we have, besides, 

 sensations of heat and cold ; that is, we perceive changes 

 of temperature. It is thought that experiments indicate 

 in the skin a separate set of end organs stimulated by 

 heat, and another set which is stimulated by cold. 



117. The Muscular Sense. Still another sensation asso- 



