BATS 45 



bat ? We suppose that they are sense-organs, but 

 all we know, or half know, about the matter is 

 ancient history ; it dates back to the eighteenth 

 century, when Spallanzani, finding that bats were 

 independent of sight when blinded and set flying 

 in winding tunnels and other confined places, 

 conjectured that they were endowed with a sixth 

 sense. Cuvier's explanation of these experiments 

 was that the propinquity of solid bodies is per- 

 ceived by the way in which the air, moved by the 

 pulsations, reacts on the surface of the wings. 

 Thus the sixth sense was a refinement, or extension, 

 of the sense of touch — an excessive sensitiveness in 

 the membrane. Blind men, we know, sometimes 

 have a similar extreme sensibility of the skin of the 

 face. I have known one who was accustomed to 

 spend some hours walking every day in Kensington 

 Gardens, taking short cuts in any direction among 

 the trees and never touching one, and no person 

 seeing him moving so freely about would have 

 imagined that he was totally blind. 



My own experiments on bats in South America 

 were inconclusive. I used to collect a dozen or 

 twenty at a time, finding them sleeping by day 

 on the trees in shady places, and after sealing up 

 their eyes with adhesive gxmi, liberate them in a 

 large room furnished with hanging ropes and 

 objects of various sizes suspended from the rafters. 

 The bats flew about without touching the walls, 

 and deftly avoiding the numerous obstacles ; but 

 I soon discovered that they were able when flying 



