SENSATIONS TOUCH 



195 



The largest of these are oval bodies having a diameter of from i to i O f 

 an inch. They are called Pacinian bodies, after Pacini, their discoverer, and 

 are abundantly distributed in the skin of the hands and feel. Other smaller 

 bodies, called touch corpuscles or tactile corpuscles, are abundant in highly 

 sensitive parts of the skin. 



In the most sensitive parts of the skin papillae are very abun- 

 dant, and the epidermis lying over them is thin. Many of the 

 papillae are also supplied with touch corpuscles. In other parts, 

 as in the heel, the outer skin is so thick that the sense of touch is 

 dulled. 



The degree of sensitiveness of the skin may be measured by 

 the power of distinguishing between two or more sensations pro- 



Fig. 178. Papillae of the Skin from the Palm of the Hand. 

 Magnified 60 diameters. 



The epidermis has been removed. 



duced at points very near each other. For instance, open a pair 

 of compasses till the points are one inch apart. Apply these 

 points to the palm of the hand, and two distinct sensations are 

 produced. Now apply the points to the skin of the arm, and the 

 sensation is such as would be produced by the application of a 

 single point. Hence we say that the hand is more sensitive to 

 touch than the arm. Two distinct sensations may similarly be 

 produced 



On the tip of the tongue, at a distance of 5 \ of an inch, 

 fore-finger A ,, 



1 



2 > 



\\ inch. 



2 inches. 

 ai 



*2 > 



3 ,, 



As a further illustration of the varying sensitiveness of the 

 skin, move the compass points over the skin, from the cheek to 

 the lips, and the distance between the points appears to be 

 gradually increasing. This power of distinguishing between 

 sensations is not due to the thinness of the epidermis, but to the 

 abundant distribution of the nerve filaments. 



O 2 



nose 



palm of the hand 



back of the hand 



back of the neck 



thigh 



back 



