.'{(!<• Prut. A. M. Mayer's Experimenttt on the supposed 



lory nerve differentiated as higlily 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 

 tvmpanic membrane and chain of ossicles in receiving and trans- 

 mittnig vibrations; while llelniholtz'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 Alysis (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 covibrations of the antennal 

 fibrillse 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- 

 scopical Society,^ entitled "Auditory Apparatus of the Culex 

 mosquito" by Christopher Johnston, M.D., Baltimore, U. S. 



In this excellent paper I found clear statements showing that 

 its talented author had surmised the existence of some of the 

 physical facts which my experiments and observations have 

 establishedf. To show that anatomical facts conform to the 



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

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

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

 the organ of Corti is the appreciation of those comi)Osite sounds whose 

 signification mammals are constantly called ui)on to interpret. 



t A short time before the death of my friend Professor Agassiz, he wrote 

 rae these words : — " I can hardly exjjress my delight at reading your letter. 

 1 feel vou have hit upon one of the most fertile mines for the elucidation 

 of a problem wliich to this «iay is a puzzle to naturalists, the seat of the 

 organ of hearing in Articulates." 



