A UDITOR Y AND SO UND-PROD UCING MECHANISMS. 595 



watch-glass is very convincing that they use these organs in 

 seeking it. 



The search for water is probably one of the most important 

 functions of the antennae in many insects, especially in those 

 which feed on dry food. 



The Antennae as Tactile Organs. Although the antennas are 

 popularly known as ' feelers,' it is very doubtful if they are 

 ever used as tactile organs in the great majority of insects. 

 Except in the Ants and Bees, I have never seen them so used, 

 and most insects carefully avoid contact between the antennas 

 and all solid bodies. Certainly the more complex forms of 

 antennae are ill adapted for such a purpose. 



10. AUDITORY AND SOUND- PRODUCING MECHANISMS. 



a. Chordotonal Organs. 



Johannes Miiller in 1826 [197] and Siebold in 1844 [278] 

 first described a tympanic ear in some Orthoptera, and in 1860 

 Leydig [269] concluded that certain organs described by 

 Braxton Hicks [292-293] in the wing nervures of some insects, 

 and in the bases of the halteres of the Diptera, are auditory 

 in function. Graber [284] made a comparative study of the 

 nervous end organs of these structures, and of others frequently 

 present in larval insects, and designated the essential nerve- 

 terminals chordotonal organs. He held that the nerve- 

 terminals of the tympanic ear, of the halteres, and of what he 

 termed the primitive chordotonal organs of larval insects, are 

 essentially similar in structure ; and he classified these as 

 primitive, poriferous, and tympanic chordotonal organs ; and, 

 reasoning from the manner in which chordotonal organs are 

 scattered over the body, concluded that the general integu- 

 ment and setae are more or less affected by sound-waves. 

 He regarded the chordotonal organs as segmental in the sense 

 that they may be present in any or in several segments, or 

 in their appendages, and held that the tympanic organs are 

 highly modified forms of the primitive and poriferous organs. 



