INSECTS. 281 
For touch, in some Insects the sucker serves as the organ; in 
others the palps which belong to the organs of the mouth, in many 
the antenne. Of taste, smell and hearing, little is known. Taste 
has its seat in the internal surface of the mouth. In some Insects 
there is a part present, which may be compared to a tongue}. 
Respecting smell different opinions are offered. On theoretical 
grounds, from presumed analogy with vertebrate animals in which 
the first pair of cerebral nerves always goes to the olfactory organ, 
BLAINVILLE has concluded, that the antenne, to which the first 
nerves from the cerebral ganglion proceed, must be the organs of 
smell*, Basrer, Rermmarus, DumeEri and Srravs place the 
sense of smell in the air-slits (stigmata), which admit the external 
air to the air-tubes. TREVIRANUS however has with reason alleged 
against this opinion, that the stigmata, inasmuch as they are 
dispersed over the body, must be useless for determining the place 
from which the odorous matter proceeds ; also that in Insects, which 
have no stigmata and which respire by tracheal gills, it would be diffi- 
cult thus to account for the sense of smell. RosENTHAL discovered 
in flesh-flies (Musca carnaria) a red-brown, folded membrane, which 
is situated in the head beneath the setting on of the antenn’. 
TREVIRANUS thinks that in sucking Insects, which are especially 
distinguished by their acute sense of smell, the seat of this sense 
ought to be sought for in the sucking organ itself, or in the 
cesophagus. If these animals suck in air, then they may smell 
with the same organ, by means of which, when they imbibe fluids, 
For the theory of vision with compound eyes it is necessary that the partial images 
be erect; hence Jon. MuELLeR (Zur vergl. Physiol. des Gesichtsinnes) has concluded 
that insects see with their compound eyes not by refraction of the rays, but by keeping 
separate the rays of light that come from different points. Hence he denies to the 
fagettes of the cornea, which are true lenses, a refractive power; yet that vision in 
insects with compound eyes occurs by dioptric means, has been shewn by Dr. A, 
Brants, and established by means of an instrument constructed on the plan of the 
insect’s eye.  Tuydschr. voor natuurl. Geschied. en Physiol., XD., 1840, pp. 12—56, 
PLE 
1 See this part figured and described in some hymenopterous insects by G. R. 
TREVIRANUS, Verm. Schriften Il. 8. 125, 131—133, Tab. x11. fig. 1, L, fig. 4, 7; Tab. 
Iv. fig. 5, 7, 8, 9, LU’ and L. 
2 See Ducus, Physiol. compar, 1. 1833, pp. 157—161, who endeavoured to establish 
the same views by experiments, as also LEFEBVRE, Ann. de la Soc. entomol. de France, 
138. 
3 Rer’s Archiv f. die Physiol. X. 8s. 427—439. 
