376 Prof. A. M. Mayer's Researches in Acoustics. 



character of the surface of a body and of its temperature — or like 

 the tongue, which at the same time distinguishes the surface, 

 the form, the temperature, and the taste of a body. Finally, I 

 take objection to this statement : — li Newport and Goureau think 

 that the antennae serve both as tactile and as auditory organs. But 

 this view is inadmissible, as Erichson has already stated, except 

 in the sense that the antennae, like all solid bodies, may conduct 

 sonorous vibrations of the air." Here evidently Siebold had 

 not in his mind the physical relations which exist between two 

 bodies which give exactly the same number of vibrations ; for it 

 is well known that when one of them vibrates, the other will be 

 set into vibration by the impacts sent to it through the interve- 

 ning air. Thus if the fibrillae on the antennae 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 is, it would have the power of 

 analyzing a composite sound by the covibration of its various 

 fibrillae 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 fibrillae on the antennae of nocturnal 

 insects are highly developed, while on the antennae of diurnal 

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

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

 be able to confirm my surmises by actual experiments on the 

 effects of sonorous vibrations on the antennal fibrillae ; 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 Mysis 3 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 antennae 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 



* " Studien liber das Gebororgan der Decapoden," Siebold und Kolliker's 

 Zeitschrift fur wissenschaftliche Zoologie, vol. xiii. 



