SENSORY ADAPTATIONS OF BATS. 



175 



the animal. This could happen without actual contact with the 

 tapes. However, it is improbable that this difference in method 

 alone would account for so great a difference in results. The 

 greater rigidity of the wires would doubtless make them easier to 

 distinguish if the air condensing theory be correct, but not if sight 

 were relied on. The bats would also have less cause to avoid 

 the tapes because striking them would cause no pain. In this set 

 of experiments a distinction was made between " hits " in which 

 the animal struck the tape squarely with the body or upper part 

 of the arm, and "touches" in which the obstruction was merely 

 brushed with the tip of the wing. The preponderance of the latter 

 bears out the assumption that no attempt was made to avoid the 

 objects. 



In these experiments each set of fifty trials was divided into five 

 groups of ten each, the object being to see whether there was a 

 progressive decrease of the percentage of hits due to experience. 

 An examination of the table shows that there is no progressive 

 decrease either in the " hits " or " touches," nor for the normal 



or blinded condition. 



Table IV. 



Avoidance of Tapes. 



Per cent, of totals for normal condition, 60.8. 

 Per cent, of totals for blinded condition, 60. 



