AUDITORY AND SOUND-PRODUCING 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 antenne in many insects, espetialiy in those 
which feed on dry food. 
The Antenne as Tactile Organs.—Although the antennz 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 antennz 
and all solid bodies. Certainly the more complex forms of 
antenne 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 sete 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. 
