The Sight of Bats 309 



attention by throwing a light stone into the water, or better 

 still, if it were near enough, a large artificial fly that would 

 not sink, and dragging it over the surface in imitation of 

 the rippling track made by a " Sedge." When this was 

 tried, the Bat would generally stoop to, and sometimes touch 

 the fly, but would never lift it. Their perception is re- 

 markably quick ; for though this species, and the Pipistrelle, 

 will often fly at a small artificial fly dangled in the air in 

 front of them, I have never seen one hooked by the mouth. 

 I believe it may occasionally happen, but it must be very 

 rare, all those I have seen caught on a fly having been 

 foul-hooked, usually in some part of the wing. A natural 

 insect is picked off the hook with the greatest neatness, 

 almost without jerking the line ; but, as just stated, I have 

 never seen a Bat hooked in the mouth even in that way. 



The exceedingly small eyes possessed by all our native 

 Bats are in marked contrast to those of most other nocturnal 

 creatures, in which the organs of sight are very large and 

 full ; and on this account it has sometimes been thought 

 necessary to suppose that, in Bats, the vision is aided by " the 

 possession of a sixth sense unknown to us." Spallanzani long 

 ago demonstrated that " Bats, when deprived of sight, and, 

 as far as possible, of hearing and smell also, still flew about 

 with equal certainty and safety, avoiding every obstacle, 

 passing through passages only just large enough to admit 

 them, and flying about places previously unknown, with the 

 most unerring accuracy, and without ever coming into 

 collision with the objects by which they passed." He also 

 stretched threads in various directions across the apartment 

 with the same result. In no case were the Bats observed 

 to come in contact with the threads ; and from these experi- 

 ments it was assumed that " it is by means of the pulsations 

 of the wings on the air that the propinquity of solid bodies 

 is perceived, by the manner in which the air reacts upon 

 their surface." * Commenting upon the above, Professor 

 St George Mivart 2 says : " Certainly, if the wing does possess 

 such sensibility, the great extent of its surface must intensify 

 it to a high degree. Now, the wing is richly supplied with 

 1 Bell's British Quadrupeds. 2 Types of Animal Life. 



