243 
Antenna of Insects. 
foot-stalk of the organ is considerably elongated. That the an- 
tennae can hardly be said to be used as tactors when of the petio- 
lated form, appears from the experiments on the Sylplia before 
noticed. Now nearly the whole of the Diptera have the antennae 
either too short for the purpose, or of a form entirely unadapted 
to be used as tactors, while the greater number of a numerous 
class of animals nearly allied to, but now separated from, insects — 
although composing the Aptera of Linnaeus — have no antennae at 
all. If the sense of touch, therefore, were the primary use of the 
organs, one would have thought they would more have resembled 
each other in structure ; at all events would never have been 
wanting, or so short as not to be applicable to the intended pur- 
pose, and it must hence appear that their use in every species 
that possesses them cannot be simply for the sense of touch. 
Now by what means is it that animals are endowed with the 
faculty of hearing ? This, as examination will prove, is purely 
mechanical. It consists in a means of feeling the vibrations of the 
atmosphere, for which I conceive the structure of the antennae in 
every species might entirely adapt them. But it may be objected 
that we have not proved insects to possess the faculty of hearing, 
before attempting to point out the particular part in which the 
sense resides. One proof must suffice, — the sexual call of the 
Ptinidce , — although many other instances might be adduced from 
almost every order and genus of insects. Entomologists are aware 
that a male of this family when in search of the female fixes his 
anterior legs firmly, and by striking with his head makes a noise 
like the tapping with one’s finger against old partitions, paste- 
board, or wainscoting. This call is perceived and returned by the 
female, often at several yards distance. The male advances and 
repeats the tapping, which is returned by the female, and this is 
alternately continued until the two have met. I do not allude to 
this in proof of the antennae being the organs of hearing, but only 
to show that insects, and even those with the simple filiform an- 
tennae, are susceptible of sound the same as the larger animals. 
Grass-hoppers and butterflies are as sensible of sound as the 
Ptinidce ; on the occurrence of any loud and sudden noise they 
immediately erect the antennae, and, when deprived of them, but- 
terflies are evidently severely affected by the loss. I once plucked 
oft’ the antennae close to the head from two or three specimens of 
Pontia Napi, Steph., when they immediately rose in the air to a 
great height, apparently having no means of directing their flight, 
and were carried in a line before the wind. I tried some of the 
Vanessa Urlicce ; and they, after rising a little, dropped down, as 
