LOCUSTS AND GRASSHOPPERS {ACRIDIID.E, 



93 



produced by others of its own species. No doubt the 

 effective sound-producing instruments are, apparently, 

 confined to the male, while the ears exist in both sexes. 

 But this need give rise to no difficulty, for it is generally 

 thought that the female has pleasure in the music of the 

 male. The real obstacle at present to the acceptance 

 of these organs as being special structures for the per- 

 ception of the music of the species, lies in the fact of the 

 existence of the acoustic organs in species that do not, 



Fig. 20.— TcratoJes inontkollis. 



so far as we know, possess phonetic organs, and are 

 incapable of stridulation in either sex. 



The difficulty at once vanishes should these species 

 really produce some sound, though we are ignorant as to 

 their doing so. It is well known that sounds inaudible 

 to some human ears are perfectly audible to others. 



