Prof. A. M. Mayer's Researches in Acoustics. 381 



The auditory apparatus we have just described does not in the 

 least confirm Helmholtz's hypothesis of the functions of the 

 organ of Corti ; for the supposed power of that organ to decom- 

 pose a sonorous sensation depends upon the existence of an audi- 

 tory nerve differentiated as highly as the covibrating apparatus, 

 and in the case of the mosquito there is no known anatomical 

 basis for such an opinion. In other words, my researches show 

 external covibrating organs whose functions replace those of the 

 tympanic membrane and chain of ossicles in receiving and trans- 

 mitting vibrations ; while Helmholtz's discoveries point to the 

 existence of internal covibrating organs which have no analogy 

 to those of the mosquito, because the functions of the former 

 are not to receive and transmit vibrations to the sensory appa- 

 ratus of the ear, but to give the sensation of pitch and to de- 

 compose a composite sonorous sensation into its elements ; and 

 this they can only do by their connexion with a nervous de- 

 velopment whose parts are as numerous as those of the co- 

 vibrating mechanism. Now, as such a nervous organization 

 does not exist in insects, it follows that neither anatomical nor 

 functional relations exist between the covibrating fibrils on the 

 antennae and the covibrating rods in the organ of Corti, and 

 therefore that neither Hensen's observations on the Mysis (as- 

 sumed by Helmholtz to confirm his hypothesis) nor mine on the 

 mosquito can be adduced in support of Helmholtz's hypothesis 

 of audition*. 



The above- described experiments were made with care; and 

 I think that I am authorized to hold the opinion that I have 

 established a physical connexion existing between the sounds 

 emitted by the female and the co vibrations of the antennal 

 fibrillar of the male mosquito ; but only a well-established phy- 

 siological relation between these covibrating parts of the animal 

 and the development of its nervous system will authorize us to 

 state that these are really the auditory organs of the insect. At 

 this stage of the investigation I began a search through the zoo- 

 logical journals, and found nearly all that I could desire in a 

 paper in vol. iii. (1855) of the ( Quarterly Journal of the Micro- 



a vertical axis. Other mammalia, however, having the axis of rotation of 

 the head more or less horizontal, have the power of facilitating the de- 

 termination of motion by moving the axis of their outer ears into differ- 

 ent directions. It is also a fact that, when one ear is slightly deaf, the 

 person unconsciously so affected always supposes a sound to come from 

 the side on which is his good ear. 



* Also, the organ of Corti having disappeared in the lower vertebrates, 

 it is not likely that it would reappear in the Articulate ; and especially will 

 this opinion have weight when we consider that the peculiar function of 

 the organ of Corti is the appreciation of those composite sounds whose 

 signification mammals are constantly called upon to interpret. 



