rit^n tirnr'. imis-trir.t. llALF HOURS WITH IXSECTS. [Packard. 



^ ulWMAHY. . / 



s.,^e. _ . . T-fia|^-4ife antennse besides being feelers are also ears has 

 l5een proved by Prof. A. M. Mayer. At a late meeting of 

 tiie 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 b}^ the ear of a composite sound into its ele- 

 mentary pendulum-vibrations ; and which elucidate the Iw- 

 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 

 antennre, 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 ph3'siology 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. Tims, 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 ai*e now shaken with more and 

 more intensity, until, having turned his body so that both 

 antennas vibrate with equal intensity, he has placed the axis 



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