SENSES OF INSECTS. 247 
the same end; something perhaps between it and touch. 
In some, however, as has been found in the Crustacea, 
an organ of hearing, in the ordinary sense, may exist at 
the base of the antennze, which may act the part in some 
measure of the external ear, and collect and transmit 
the sound to such organ ?. 
That numerous antenne, as a secondary function, ex~- 
plore by ¢ouch, is admitted on all hands, and therefore I 
need not enlarge further upon this point; but shall pro- 
ceed to inquire whether insects do not possess some other 
peculiar organs that are particularly appropriated to this 
sense. First, however, I must make some general ob- 
servations upon it. Of all our senses, touch is the only 
one that is not confined to particular organs, but dispersed 
over the whole body: insects, however, from the indu- 
rated crust with which they are often covered, feel sen- 
sibly, it is probable, only in those parts where the nerves 
are exposed, by being covered with a thinner epidermis, 
to external action. Not that they cannot feel at all in 
their covered parts; for as we feel sufficiently for walk- 
ing, though our feet are covered by the thick sole of a 
boot or shoe, so insects feel sufficiently through the crust 
of their legs for all purposes of motion. Besides, the 
points that are covered by a thinner cuticle are often nu- 
merous; so that touch, at least in a passzve sense, may be 
pretty generally dispersed over their bodies; but active 
or exploring touch is confined to a few organs, as the 
antenne, the palpi, and the arms. The two last I shall 
now discuss. 
~ * Marcel de Serres thinks he has discovered an organ of hearing 
in most insects, but he does not state its situation. Mem, du Mus. 
1819. 99. 
4 
