PERCEPTIONS OF ANIMALS. 567 



of smell, in particular, is often spread over a 

 vast extent of surface, in a cavity occupying the 

 greatest part of the head ; so that the per- 

 ceptions of this sense must be infinitely diver- 

 sified. 



Bats have been supposed to possess a peculiar, 

 or sixth sense, enabling them to perceive the 

 situations of external objects without the aid 

 either of vision or of touch. The principal facts 

 upon which this opinion has been founded were 

 discovered by Spallanzani, who observed that 

 these animals would fly about rapidly in the 

 darkest chambers, although various obstacles 

 were purposely placed in their way, without 

 striking against or even touching them. They 

 continued their flight with the same precision as 

 before, threading their way through the most 

 intricate passages, when their eyes were com- 

 pletely covered, or even destroyed! Mr. Jurine, 

 who made many experiments on these animals, 

 concludes that neither the sense of touch, of 

 hearing, or of smell, was the medium through 

 which bats obtain perceptions of the presence 

 and situation of surrounding bodies ; but he 

 ascribes this extraordinary faculty to the great 

 sensibility of the skin of the upper jaw, mouth, 

 and external ear, which are furnished with very 

 large nerves.* 



* Sir Anthony Carlisle attributes this power to the extreme 

 delicacy of hearing in this animal. 



