Sensory Discrimination: Hearing 123 



Normal females ran to the vessel which contained the 

 chirping male, but ignored the other vessel: females 

 whose "tympanal organs" on the forelegs had been 

 operated on did not react to either vessel. That the 

 response was not to an odor liberated by the move- 

 ment of the male's wings in chirping, was shown by 

 removing the edges of the wings, so that their motion, 

 while otherwise unchanged, was noiseless : the response of 

 the females ceased. 



It seems likely that the auditory sense, if it exists in 

 insects, would be confined to those which produce sounds, 

 and its qualities limited within the range of such sounds. 

 Turner (731), however, finds that silkworm moths, alighted 

 on hanging shelves and thus protected from jarring, respond 

 by waving their wings when an organ pipe, a pitch pipe, 

 and various notes on the Gal ton whistle are sounded. 

 One species, which failed to respond, he rendered more 

 excitable by rough handling, and then succeeded in stimu- 

 lating the sound reactions. Several different species of 

 Catocalo moths were found to respond to high notes on the 

 Gal ton whistle, either by flying or by quivering their 

 wings. By touching the insect at the moment when the 

 tone was sounded, thus giving it a " life significance" to the 

 insect, some of the moths were trained to react to a lower 

 organ tone (256 vibrations) even when they were not 

 touched. These moths are not known to make sounds 

 (733). Most species of ants produce no sound that the 

 human ear, even with the aid of a microphone (441), can 

 detect, although certain East Indian species are reported 

 to make a loud hissing noise when disturbed (760), and 

 some American species are said to chirp (202, 782). 

 Ch. Janet maintains that ants of the Myrmicidae make 

 a stridulating noise (357, 358). The weight of evidence 



