ELEMENTS OF ENTOMOLOGY. 
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Fissile, with the knob divided longitudinally into lamina; or plates ; 
Perfoliate, having the. knob divided horizontally; 
Pectinate, having a longitudinal series of hairs or processes project- 
ing from them in form of a comb; 
Furcate, or forked, having the last joint divided into parts. 
Nothing has been the source of greater speculation than the use of. 
the antenna:: nor is this surprising, considering the variety constantly 
exhibited in their structure, occupation, and appearance. Some insects 
seem to keep them in continual employment; in others they arc pre- 
served in a quiescent state. Those of the ichneumon show an inces- 
sant tremulous vibratory motion, anxiously searching into every cre- 
vice; while those of the carrion-fly scarcely appear endowed with flexi- 
bility. They have successively been considered as the organs of hear* 
ing, feeling, smell, and taste, or of an unknown and indefinite sense. 
Bonnet seems to think the antenna; the organ of smell. “Different 
insects,” lie observes, “ have an exquisite sense of smelling, the organ 
of which is yet undiscovered. May it not reside in the antenna;?’' 
Lehmann, from the result of experiments on this subject, denies that 
the antennae, are the olfactory organ. lie made an opening an inch wide 
in the side of a glass vessel, and surrounded the edge with wax, so 
that a close covering could be applied. An apejturewas made in this 
covering, through which either the whole head, or the antennae only 
of an insect coidd be introduced, By means of a tube the glass was 
filled with penetrating odours, vapours, or heated air; but neither the. 
fumes of sulphur nor burnt feathers produced the smallest effect on 
butterflies, bees, or beetles, whose ai itenrue were exposed to them. He, 
judges that the olfactory organ must he sought in the spiracula; “ for 
what else,” says he, “ is the sense of the particles inspired than smell- 
ing ? ” 
Bonsdorf, in discussing whether the antenna; may be the seat of 
hearing, mentions an experiment where a species of beetle, whose pe- 
culiar property it is to fold in the antenna; when alarmed, did so on a 
loud noise being suddenly made, and fell to the ground, according to 
the nature of the species. But, notwithstanding that the animal pre- 
viously reposed in a tranquil state, his experiment cannot be consi- 
dered altogether conclusive. But terflies are seen to erect their an- 
tenna* on any sudden noise, and many Coleoptera to depress them ; 
which may equally arise from the sudden shock or vibration of tire air. 
Spiders also, which want antenna*, arc extremely sensible of sound. 
Lehmann relates that, on observing one descend from the roof by its 
thread in quest of a female, while he was reading, he began to read 
aloud: the animal, alarmed at the noise, retreated upwards; he was 
silent, and it returned ; on again reading aloud, it testified alarm and 
ascended its thread; nor was its apprehension of danger dispelled,, 
until familiarized with the sound or conquered by the object of jts 
