150 W'hildkcr : TJtc Devclopincnf of the Srnscs i)i Bdts. 



expanse of the wing- membranes —the wing's being- literally a 

 mass of nerves. In support of this, it is worth noting; that 

 those species which seek the darkest retreats in the daytime, 

 and fly the latest at nig^ht, are furnished not only with larg-e and 

 sensitive ear membranes, but have additional developments of 

 sensitised skin which appears expressly desig-ned to aid this 

 mvsterious sense. This additional development of sensitive 

 skin, which is frequently of a leaf-like shape, is undoubtedly 

 placed in the position where it will be of most use, /.<'., on the 

 top of the nose, so that these creatures, at least, can safely be 

 advised to follow their noses when in a dark place. 



Whatever explanation be accepted of the power of bats 

 to recog-nise the nature and locality of objects independently of 

 sig^ht, it is a wonderful thing", for all other living- creatures, so 

 far as we know, derive such impressions almost exclusively 

 through the medium of light and reflection. That this is not 

 so with bats is easily shown. As their early prog-enitors became 

 more and more nocturnal in habits, and darker retreats came to 

 be soug-ht in the daytime, more acute perception of objects in 

 the dark became necessary to them. If lig-ht had played any 

 part in this essential perceptive development, the eyes and 

 optical nerves already sensitised to it would have been de- 

 veloped to the required degree, and not the nerves in other 

 parts of the body, sensitive not to light but to touch. 



It is most difficult to estimate to what extent the true eye- 

 sight of bats is developed, the sense we haxe just been con- 

 sidering and classed with touch approximating so closely in the 

 impressions it conveys to the sense of sight, that, although we 

 know that a bat has received certain knowledge of its surround- 

 ings, it is often very difficult to say through which medium the 

 impression has been conveyed to it. Nevertheless, a bat has 

 eyes and can see, and the saying 'as blind as a bat' is 

 certainlv anything but a happy one, for it is almost certain that 

 it is, partly at least, by sight that a bat is enabled to catch the 

 minute insects on which it feeds, when fl\ing rapidl\ , in ainiost 

 total darkness. 



Still it is strange, very strange, that whilst in the case of 

 niost nocturnal animals the eyes have become exceptioiially 

 large and convex in order to take in as much lig^ht as possible, 

 in the case of bats, where one would have looked especially for 

 such development, the eyes have become reduced to the most 

 minute size. We can understand the similar paradox in the 

 case of the mole, for in its subterranean workings it can rely 



Naturalist, 



