100 
HALF HOURS WITH INSECTS. 
[Packard. 
That the antennae besides being feelers are also ears has 
been proved by Prof. A. M. Mayer. At a late meeting of 
the National Academy of Sciences, held in New York, he 
made a series of exceedingly ingenious experiments, which 
confirm the theorem of Fourier as applied by him in his 
propositions relating to the nature of a simple sound, and to 
the analysis by the ear of a composite sound into its ele¬ 
mentary pendulum-vibrations; and which elucidate the hy¬ 
pothesis of audition of Helmholtz. Placing a male mosquito 
under the microscope, and sounding various notes of tuning 
forks in the range of a sound given by the female mosquito, 
the various fibres of the antennae of the male mosquito 
vibrated sympathetically to these sounds. The longest 
fibres vibrated sympathetically to the grave notes, and the 
short fibres vibrated sympathetically to the higher notes. 
The fact that the nocturnal insects have highly organized 
antennae, while the diurnal ones have not; and also the fact 
that the anatomy of these parts of insects shows a highly 
developed nervous organization, lead to the highly probable 
inference that Prof. Mayer has here given facts which form 
the first sure basis of reasoning in reference to the nature of 
the auditory apparatus of insects. 
“These experiments were also extended in a direction 
which added new facts to the physiology of the senses. If 
a sonorous impulse strike a fibre so that the direction of the 
impulse is in the direction of the fibre, then the fibre remains 
stationary. But if the direction of the sound is at right 
angles to the fibre, the fibre vibrates with its maximum in¬ 
tensity. Thus, when a sound strikes the fibrils of an insect, 
those on one antenna are vibrated more powerfully than the 
fibrils on the other, and the insect naturally turns in the di¬ 
rection of that antenna which is most strongly shaken. The 
fibrils on the other antenna are now shaken with more and 
more intensity, until, having turned his body so that both 
antennae vibrate with equal intensity, he has placed the axis 
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