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ORIGINAL COMMUNICATIONS. 



Auditory Apparatus of the Culex Mosquito. By Chris- 

 topher Johnston, M.D. Baltimore, United States. 



It is more tlian presumable that creatures endowed with the 

 faculty of producing and voluntarily modifying distinct sounds, 

 should also possess organs for the apprehension and ap- 

 preciation either of rhythmic or irregular sonorous vibrations. 

 The insect tribes are precisely in this category ; the apparatus 

 by which is produced their song, their hum, or their chirp, is 

 extremely varied, and the sounds which emanate from it offer 

 a great diversity, even in the larger individuals, or, in other 

 words, so far as our own auditory organs permit our sense to 

 follow the rising scale. That these sounds are in some Avay 

 perceived by insects themselves we have abundant evidence 

 in the Cricket {Gryllus\ the Grasshopper (Cicar/a), and espe- 

 cially in the Bee, which responds to another individual in a 

 particular note.* Some insects are supposed to be silent ; 

 while the smaller varieties, fi-om the exceeding minuteness 

 of their parts, give rise to vibrations so rapid as to be in- 

 appreciable by our ears. 



It will readily be admitted that if there be a limit for acute 

 sounds, corresponding with the smallest number of vibrations 

 capable of producing an auditory impression, there must also 

 be a limit to the development of an acoustic apparatus ; and 

 " we cannot," as Duges remarks, " conceive of a true micro- 

 scopic ear." In the Protozoa, therefore, and possibly in the 

 most diminutive insects, we may abandon the idea of a cen- 

 tralization of the faculty of perceiving vibrations, and feel 

 assured that the sense of touch, generally distributed, stands 

 in the stead of a " sensorial speciality." 



From analogy, pursued downwards, we might expect to 

 discover the localization of the " sensorial speciality," when 

 it exists, in the head of insects, or else from analogy, pursued 

 upwards, might we sometimes look for its seat elsewhere. In 

 fact we find numerous descriptions of an auditory apparatus 

 situated in the head of certain species, and in parts connected 

 with the thorax of other species ; but many of the observers 

 have failed to convince others than themselves ; and other 

 writers have assigned, in some instances, a different function 

 to the organs spoken of as being concerned in audition. 



* Duges. Physiol. Comp. 

 vol. III. H 



