The Senses of Animals. 



247 



are specially modified to form tactile cells, or tactile 

 corpuscles, in contact with or surrounding the axis-fibre or 

 its expansion (Fig. 23). 



Hairs are delicate organs of touch, though, of course, 



Pig. 23. — Tactile corpuscles. 

 1. In the beak of a goose. 2. In the finger of a man. 3. In the mesentery of a cat. 



this is not their only function. They act as little levers 

 embedded in the skin. 



Turning now to the vertebrate animals other than 

 man, we find in them a sense of touch closely analogous 

 to our own. As in us, so in them,, the specially mobile 

 parts are eminently sensitive and delicate ; for instance, 

 the lips in many animals, such as the horse, and the finger- 

 like organ at the end of the elephant's trunk. In some of 

 them special hairs are largely developed as organs of touch, 

 as in the whiskers of the eat and the long hairs on the 

 rabbit's lip. With the aid of these the rabbit finds its way 

 in the darkness of its burrow ; and it is said that, deprived 

 of these organs, the poor animal 'blunders about, and is 

 unable to steer its course in the dark. 



The wing of the bat is very sensitive to touch ; and it 

 is supposed that it is through this sense that the bat is 

 able to direct its course in the darkness of caves. Miss 

 Caroline Bolton thus describes an experimental trial of 

 this power of the bat at which she was herself present. 

 A room, about twenty feet by sixteen, was arranged with 

 strings crossing each other in all directions so as to form a 

 network with about sixteen inches space between the strands. 

 To each string was attached a bell in such a way that the 

 slightest touch would make it ring. One corner of the room 



