Auditory Apparatus of the Culex mosquito. 355 
ning air. Thus, if the fibrille on the antenne of an insect 
should be tuned to the different notes of the sound emitted by 
the same insect, then when these sounds fell upon the antennal 
fibrils the latter would enter into vibration 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 1s, it would have the power of 
analyzing a composite sound by the covibration of its various 
fibrillee 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 fibrille on the antenne of nocturnal 
insects are highly developed, while on the antenne of diurnal 
insects they are either entirely absent or reduced to mere rudi- 
mentary filaments, caused me to entertain the hepe that I should 
be able to confirm my surmises by actual experiments on the 
effects of sonorous vibrations on the antennal fibrille; also the 
well-known observations of Hensen* encouraged me to seek in 
aérial msects for phenomena similar to those he had found in 
the decapod the Mysis, 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 antennz 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 antenne of these insects are twelve- 
jomted ; 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 I saw certain of the fibrils enter into vigorous 
vibration, while others remaimed comparatively at rest. 
* “Studien tiber das Gehororgan der Decapoden,”’ Siebold und KOlliker’s 
Zeitschrift fur wissenschaftliche Zoologie, vol. xiii. 
