94 ORGANS OF HEARING IN INSECTS. 



That these plumose hairs, then, really serve for hear- 

 ing may be inferred, not only from their structure and 

 position, but also from the observed fact that they 

 respond to sound-vibrations. 



Hensen's observations* have been repeated and 

 verified by Helmholtz. 



The Organs of Hearing in Insects. 



I now pass on to insects. There has been great 

 difference of opinion as to the seat of the organ of 

 hearing in this group. 



The antennae have, as already mentioned, been re- 

 garded as ears by many distinguished authorities, 

 including Sulzer, Scarpa, Schneider, Bolk-Hausen, 

 Bonsdorff, Carus, Strauss-Durkheim, Oken, Burmeister, 

 Kirby and Spence, Newport, Landois, Hicks, Wolff 

 and Graber, who have supported their opinion by 

 numerous observations. 



Kirby states that once " a little moth was reposing 

 upon my window ; I made a quiet, not loud, but distinct 

 noise : the antenna3 nearest to me immediately moved 

 towards me. I repeated the noise at least a dozen times, 

 and it was followed every time by the same motion of 

 that organ, till at length the insect, being alarmed, 

 became more agitated and violent in its motions." 

 And again : " I was once observing the motions of an 

 Apion (a small weevil) under a pocket microscope ; on 

 seeing me it receded. Upon my making a slight 

 but distinct noise, its antennae started. I repeated tl e 

 noise several times, and invariably with the same 

 effect." t 



* " Sensations of Tone." 



t Introduction to " Entomology," Kirby and Spence, vol. iv. 



