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ANTENNA. 
these animals are still to be considered as belong- 
ing to the insect tribe: whence, the later ento- 
mologists have rather been disposed to reject the 
antenne as a constant and invariable character- 
istic. The horns of snails, and other animals of 
the genus Mollusca, do not strictly come under 
the description of antenne, from being retractile, 
and wanting articulations. Most larvae want an- 
tenne ; and although present in several, they are 
of a very different quality from what they appear 
in the perfect insect; from this, however, there 
are some exceptions, in which they are the same 
in both. 
In the mature insect, the antenne are ex- 
tremely diversified in size, shape, and organiza- 
tion. In the Notonecta, or boat-fly, they can 
with difficulty be discovered; and in the Nepa, 
or water-scorpion, they are so minute that intel- 
ligent naturalists have been induced to deny their. 
existence. Some consist of only two or three 
articulations, such as those of the common fly; 
others of between two and three hundred, such 
as those of the lobster. From this diversity in 
appearance they are denominated cetaceous, ser- 
rated, clavate, filiform, pectinated, and the like. 
In a few instances they are short, and terminated 
by a single hair, as in the gadfly; others are 
beautifully pectinated, as in various phalence; or 
resemble tufts of feathers, as in musquitoes and 
tipule. Such antenne form the most elegant 
microscopical objects. Not only is there a great 
difference among the antenne of insects in gen- 
eral, but also in those of the same genus, and 
even of the same species. The queen-bee and 
workers have fourteen articulations, while the 
males have only thirteen. The structure of those 
of the male is likewise sometimes found different : 
the male musquito has feathered antenna, those 
of the female are filiform and plain. We should 
also observe, that the antenne of quite different 
kinds of insects are known to resemble each other. 
The substance of the antenne is not muscular: 
they are composed of a series of minute cylinders 
jointing into each other, and enclosing an ap- 
paratus of nerves, muscles, air-pipes, and cells. 
Nothing has been the source of greater specu- 
lation than the use of the antennze; nor is this 
surprising, considering the variety constantly ex- 
hibited in their structure, occupation, and appear- 
ance. Some insects seem to keep them in con- 
tinual employment ; in others they are preserved 
in a quiescent state. Those of the ichneumon 
show an incessant tremulous, vibratory motion, 
anxiously searching into every crevice; while 
those of the carrion fly scarcely appear endowed 
with flexibility. They have successively been 
considered as the organs of hearing, feeling, smell, 
and taste; or of an unknown and indefinite sense. 
Bonnet seems to think the antennz the organ 
of smell. Different insects, he observes, have an 
exquisite sense of smelling; the organ of which 
is yet undiscovered. May it not reside in the 
antenne? Insects are unquestionably affected 
201 
by the emanation of odours; the wasp is attracted 
by honey, the bee by flowers, and the fly by car- 
rion. Nay, a plant which exhales the smell of 
carrion, deceives the fly, which alights on it to 
deposit its eggs. Yet we should reflect that the 
means of perception are not indispensably the 
same in animals provided with antenne as in 
those of larger size, or those without them, pro- 
vided with an organ exclusively adapted to re- 
ceive such impressions. Lehmann, from the result 
of experiments on this subject, denies that the 
antenne are the olfactory organ. He judges that 
the olfactory organ must be sought in the spira- 
cula; “for what else,” says he, “is the sense of 
the particles inspired than smelling?” Lehmann 
also denies that the antennz are at all connected 
with the sense of taste. But it is evident, he 
thinks, that they are adapted for feeling in an 
eminent degree. On attending to the motions of 
the curculio, an animal which advances with slow 
and cautious steps, the antennee are always seen 
extended before it, as if feeling the way. When 
the cerambya is at rest, no use is made of them; 
when it begins to move they are stretched out, 
and employed in examining what is fit for each 
progressive step. The aphides rarely move; but 
no step is ever made until the ground is ascer- 
tained by the antennze. Those of the ichneumon 
flies are in unremitting action, exploring all the 
surrounding objects, and leaving nothing un- 
touched. Marsham has observed the Jehnewmon 
investigator, in searching out a proper place for 
depositing its eggs, approach a hole in a wooden 
post, and thrust in its long antennee up to the 
head ; then retire and try other holes and crevi- 
ces, until a suitable one was found. If the onis- 
cus is withdrawn from its dark retreats, it refuses 
to advance a single step, until the safety of its 
march has been ascertained by means of its an- 
tenne. On touching the Sepha germanica, it 
immediately closes up, counterfeiting death ; and 
all the limbs, along with the antenne, are closely 
contracted. But when its apprehensions of dan- 
ger diminish, the antenne are cautiously unfold- 
ed; if nothing threatens, the whole members 
gradually expand, and the animal makes its 
escape; if still uncertain of security, the anten- 
nee are replaced down the thorax. The utility 
of such a sense, residing to an exquisite degree 
in the antenne, may readily be appreciated, 
on attending to the natural abode of numerous 
animals provided with them. Many dwell in 
dark, irregular chasms, clefts, or crevices, which 
requires an organ of extreme sensibility to ex- 
plore their way. 
Although feeling may thus be the principal 
office of the antenne, those of some insects are 
so small, and placed in such a situation, that for 
this office only they can apparently be of very 
little use. Lehmann thence supposes, that they 
may be adapted for conveying impressions of the 
state of the air. The opinions of those, he ob- 
serves, who maintain the possibility of other senses 
