SENSORY ADAPTATIONS OF BATS. 1 87 



they are developed to a degree which we know nothing about 

 from direct experience. 



Watson ('07) found that the ability of white rats to learn a 

 maze was not impaired by the destruction of either the eyes, the 

 olfactory lobes, the middle ear or the vibrissae, or by anesthetizing 

 the paws or nose, or eliminating temperature and air currents. 

 When the maze was rotated through an angle of 90 degrees, they 

 were confused, but when it was rotated through i8o degrees they 

 were again able to find their way. Watson believes that " static 

 sensations or some non-human modality of sensation " are neces- 

 sary to explain the behavior of these rats. 



Watson and Carr ('08) believe that in the white rats, orien- 

 tation is attained by traversing a unit of the maze. In man, a 

 train of acts which have become habitual may be set off by some 

 visual or other sensory impulse. In the lower animals such acts 

 may be set off by a " kinaesthetic sensation," such as traversing a 

 unit of the maze and getting the appropriate "feel " of direction 

 from some combination of motor impulses or acts. 



Bats are more difficult to work with than rats because their 

 reactions, always uncertain, are seriously disturbed by any kind 

 of operation. Those that I have had have also lacked vitality 

 and have died before extensive experiments could be completed. 

 However, the experiments here described seem to warrant the 

 assumption that they also have something akin to "static sensa- 

 tions" which enables them to retrace their way to a point at which 

 they have been before, without depending on the other five senses. 



It is not the purpose of the present paper to discuss the nature 

 of this sense. It may be the same as the " kinsesthetic " sense 

 of Watson. However it is not necessary for a bat to perform 

 an act similar to that of the rats traversing a unit of the maze 

 in order to obtain orientation. The only movements of the bats 

 which seemed to have any connection with orienting was a slow 

 turning of the head in various directions. The purpose of this 

 I could not determine. It is conceivable that if the sense of loca- 

 tion is situated in the semicircular canals, a rotation of the head 

 might arouse various sensations, one of which would serve as a 

 clue to position. 



There is reason to believe that bats have good memory. On 



