174 WALTER LOUIS HAHX. 



with the hair covered, and 24.4 per cent, when normal. For five 

 P. subflaviis the proportions were 32.4 per cent, and 25.2 per cent. 



The difference of proportion for these three species is consider- 

 able and there is no reason apparent. It is not safe, however, to 

 infer that there is any important difference in the sensibility of 

 the hairs of these species for there is a large individual variation, 

 both the lowest and highest individual percentages being found 

 in My Otis hicifugns. 



The figures indicate that the organs of touch, located in the 

 skin and probably associated with the hairs, are of value in en- 

 abling the animals to avoid objects, though of lesser value than 

 the auditory organs. However, it is necessary to take into con- 

 sideration the mechanical effect of the vaseline in making the 

 wing membranes sticky. Invariably the flight of the bat became 

 more labored, it stopped more frequently and was less readily 

 dislodged from its perch after being covered with the vaseline, 

 although the animals were able to equilibrate and alight on either 

 vertical or horizontal surfaces as well as when in the normal 

 condition. 



In order to check the experiments made at the "University 

 Farm " and to determine some points that were overlooked, addi- 

 tional experiments were made in the laboratory at Bloomington, 

 in December, 1907. In place of the wires spaced at irregular 

 intervals, white cotton tapes, 15 millimeters in width, were 

 stretched from floor to ceiling and spaced regularly, the distance 

 between them being 12 inches. The average expanse of Myohs 

 hicifugiis is 10 inches and there was thus an allowance for error 

 of 2 inches, supposing the bats aimed at the middle of the space. 

 However, the percentage of hits for five individuals, of M. luci- 

 fugus in 50 trials each was 58.4 when normal and 60 with the 

 eyes covered, as against an average of 25 per cent, in the earlier 

 experiments. 



This discrepancy can perhaps be accounted for in part by the 

 method of counting hits. When the wires were used the hits 

 were counted only when audible. With the tapes it was necessary 

 to adopt some other method of counting and a " hit " was recorded 

 every time that the moderately loose tapes were set in motion by 



