230 THE CAUSES WHICH PROPAGATE 



CHAPTER VI. 



THE OEGAN OF HEARING IN INSECTA. 



That insects may communicate the emotions which stir them 

 by instrumental music^ and produce the phenomena we witness, 

 it is necessary they shoukl have an organ of hearing. And that 

 an organ of hearing may be found in lusecta, we infer when we 

 notice those provided Avith musical files perform in turn, or on 

 reconnoitre, and when we find them respond to their notes, or 

 to those of a slightly different pitch, artificially imitated.^ A 

 little observation enables us to detect this feature in the music 

 of cicadae, grasshoppers, and leaf -crickets, and it exists doubtless 

 in that of the crickets or cockroaches. We may likewise observe 

 it in the stridor of some longicorn beetles sith divo, and in 

 some lamellicorns when boxed together. That the required 

 organ should present structural variety I think we may con- 

 clude from the diverse pitch, colour, and rhythm of the notes, 

 or from their range of expression. We shall also, perhaps, find 

 reason to look for an auditory organ in those flies and bees 

 whose whining, spiracular music presents kindred phenomena, 

 or in certain butterflies, moths. Solitary Ants, and Neuroptera (?), 

 with a capacity for music. Similar deductions may be also 

 drawn from the wing-beating employed by some moths in 

 pairing. 



Many seeking their inference in the Vertebrata, however, have 

 been predisposed to look for organs of sense with constant 

 position in the cephalic ring; and thus the antennae have come 

 to be attributed with the faculty of hearing. This idea was 

 once very prevalent. Professor J. Rennie has proposed to dub 

 them ears, chiefly because insects adduct them at certain 



* See previous chapters. 



