THE ORGANS OF SENSATION 



supply of touch-corpuscles (Wiedersheim), 1 for in animals the 

 hairs which are freely provided with nerves act as touch-organs, 

 and the touch-papillse occur almost exclusively on non-hairy 

 parts. 



In the chimpanzee and gorilla rows of touch-papillae lie 

 among the rough furrows in the palm of the hand (see Fig. 85). 



Pacinian corpuscles are found widely distributed in the 

 Mammalia generally. Meissner's corpuscles, on the other hand, 

 small oval bodies measuring in man O'o66-crii mm. long and 

 O'O34-O'O56 mm. broad, appear to be confined to man, apes (on 



FIG. 85. Touch-bulbs in the 

 hand of the ape. (Koll- 

 mann.) 



J 



FIG. 86. Touch-bulbs in the human hand. 

 (After Hibert.) i, first; n, second; 

 in, third row. 



the hand) and elephants (in the papillae of the tongue) 

 (Corti) 2 (see Fig. 86). 



The tongue serves as an organ of touch and feeling not 

 only in reptiles but also in birds and mammals, and for this 

 purpose the tongue is supplied partly with touch-corpuscles, and 

 partly with free nerve endings in the epithelium. The anterior 

 part of the snake's tongue, with its papillae and touch-corpuscles, 

 is specially adapted to the perception of tactile sensations. The 

 papillae in the bird's tongue are richly supplied with touch-buds 

 and Pacinian corpuscles. Meissner's corpuscles occur on the 



1 Wiedersheim, loc. cit., p. 149. 2 Bonnet, op. cit., p. 448. 



