Vo/. XV. September, igo8. No. 4.. 



BIOLOGICAL BULLETIN 



SOME HABITS AND SENSORY ADAPTATIONS OF 

 CAVE-INHABITING BATS. II. 



WALTER LOUIS HAHN. 



PAGE. 



Experiments on Avoiding Obstacles 165 



Object of Experiments 166 



Method 166 



Kinds of Mutilation 168 



Avoidance when Normal 168 



Avoidance when Blindfolded 169 



Avoidance with Ears and Tragi Removed 170 



Avoidance with Meatus Stopped 170 



Avoidance with Hair Covered 173 



Probable Percentage of Hits 17^ 



Additional Observations 177 



Experiments on Association and the Sense of Direction 178 



Visual Associations I?^ 



Sound Associations 178 



Place Associations I79 



Method 179 



Details of Experiment 180 



Reversing Cage 183 



Results of Experiments 185 



Evidence as to Kind of Associations Formed 186 



Memory 1 87 



Utility of Sense of Direction 189 



Conclusions 189 



Literature 191 



Experimental Studies. 



I. Avoidance of Objects. 



As early as 1 794 Spallanzani experimented with bats in which 

 one or more of the senses had been destroyed. I have not had 

 access to the original account of his experiments. According to 

 the account of these experiments given by Godman ('26) and 

 Flower and Lydekker ('91), bats deprived of sight, hearing and 



165 



