Aiiilifnrii Apjiiirdtns i if the (Jiilcx mosquitn. ,'».")."> 



iiing air. Thus, if the fibrillae on the anteniue of an insect 

 should be tuned to the different notes of the sound emitted by 

 the same insect, tlien when these sounds fell upon the antenna! 

 fibrils the latter would e/iter into viljration with those notes of 

 the sound to which they were severally tuned; and so it is evi- 

 dent that not only could a properly constructed antenna serve 

 as a receptor of sound, but it would also have a function not 

 possible in a membrane; that is, it would have the power of 

 analvzinj; a composite sound by the covibration of its various 

 tibrillaj to the elementary tones of the sound. 



The fact that the existence of such an antenna is not only 

 supposable, but even highly probable, taken in connexion with 

 an observation I have often made in looking over entomolo- 

 gical collections, viz. that fibrillse on the antennje of nocturnal 

 insects are highly developed, while on the antenna3 of diurnal 

 insects they are either entirely absent or reduced to mere rudi- 

 mentary filaments, caused me to entertain the hope that 1 should 

 be able to confirm my surmises by actual experiments on the 

 effects of sonorous vibrations on the antennal fibrillEe; also the 

 well-known observations of Hensen* encouraged me to seek in 

 aerial insects for phenomena similar to those he had found in 

 the decapod the Mijs'is, and thus to discover in nature an appa- 

 ratus whose functions are the counterpart of those of the appa- 

 ratus with which I gave the experimental confirmation of 

 Fourier's theorem, and similar to the supposed functions of the 

 rods of the organ of Corti. 



The beautiful structure of the plumose antennae of the male 

 Culex mosquito is well known to all microscopists ; and these 

 organs at once recurred to me as suitable objects on which to 

 begin my experiments. The antennrc of these insects are twelve- 

 jointed; and from each joint radiates a whorl of fibrils; and the 

 latter gradually decrease in their lengths as we proceed from 

 those of the second joint from the base of the antenna to those 

 of the second joint from the tip. These fibrils are highly elastic, 

 and so slender that their lengths are over three hundred times 

 their diameters. They taper slightly, so that the diameter at the 

 base is to the diameter near the tip as 3 to 2. 



I cemented a live male mosquito with shellac to a glass slide, 

 and brought to bear on various fibrils a one-fifth objective. I then 

 sounded successively, near the stage of the microscope, a series 

 of tuning-forks with the openings of their resonant boxes turned 

 towards the fibrils. On my first trials with an Ut^ fork of 512 

 vibrations per second, I was delighted with the results of the 

 experiments ; for 1 saw certain of the fibrils enter into vigorous 

 vibration, while others remained comparatively at rest. 



* " Stiulien iiber das Gehororgan der Decapoden," Siebold und Koiliker's 

 Zeitscfirift fur wisseftschaftUclie Zooloc/ie, vol. xiii. 



