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ANATOMY AND PHYSIOLOGY 
that this is one of the uses to which they are emin- 
ently subservient. 
Still, however, touch is only a secondary function 
of the latter ; the generality of authors now agree in 
regarding them as the appropriate organs of hearing . 
When a beetle with long antennae is suddenly sur- 
prised by a loud sound, it stretches these members 
outwards and holds them immoveable as if listening, 
and moves them carelessly again when the noise has 
ceased. They are two in number, in this, as well 
as in their prominent situation, corresponding to the 
ears of the vertebrata. On close examination a soft 
articulating membrane can be detected at their base, 
beneath which the antennal nerve is conducted; 
this may be considered as the last vestige of a tym- 
panum, and the nerve alluded to, as an acoustic 
nerve. Viewed in this light, the stalk of the anten- 
nae must be employed to collect the pulses or vibra- 
tions of the atmosphere and transmit them to the 
sensorium, an office for which their branched, plu- 
mose, and other delicate structures all tending to 
increase the extent of their surface, eminently fit 
them. This view receives strong confirmation from 
the circumstance of the auditory organ of the Crus- 
tacea being placed at the base of the antenme, some- 
times even in the radical joint. It has been well 
observed also that the organs in question are almost 
always very fully developed in such insects as emit 
sounds as a signal call to the sexes a case in which 
hearing requires to be more than usually acute. 
Crickets, Grylli, and Cerambycidse, may be given as 
