56 Organs of Smell in Insects. 



antenna. The function of the antennas is now pretty well 

 if not wholly understood. That they often serve as most 

 delicate touch -organs no observing apiarist can doubt. 

 Tactile nerve-ending hairs are often found in great num- 

 bers. With the higher insects, like most Hyiiienopterons. 

 this tactile sense of the antenniB is doubtless very import- 

 ant. 



It is now fully demonstrated that the sense of smell is 

 located in the antennae. Hulzer in the last century sug- 

 gested that an unknown sense might exist in the antennae. 

 Reaumur, Lyonet, Bonnet, etc., thought this might be the 

 sense of smell. Dumeril, Lehrman, who said that a 

 nerve vessel and muscle entered the antennae, and Cuvier, 

 etc., thought the sense of smell was located in the spiracles 

 or breathing mouths. Huber thought the organ of smell 

 was located in the mouth. Latreille and Newport, of this 

 century, believed the antennae contained the organs of 

 hearing. Strauss-Durkheim located them in the spiracles. 

 While Wolff wrote a beautiful monagraph to prove that 

 the sense of smell was situated in the hypo-pharynx beneath 

 the labrum. Erichson in 184S discovered pits in the 

 antennae — pori — covered with a membrane (Fig. 11, p) 

 which he thought organs of smell. The next year Bur- 

 meister found hairs in these pits in beetles, which varied 

 according as the beetle ate plant-food or carrion. 



Leydig in 1855 showed that Erichson was correct, that 

 there were pits also on the antenna and pegs (Fig. 11,^) 

 or tooth-like hairs, perforated at the end — olfactory teeth. 

 It remained for Hauser (1880) to complete the demonstra- 

 tion. He experimented with insects by the use of carbolic 

 acid, turpentine, etc. He found that this greatly disturbed 

 the insects when their attennae were intact, and that even 

 after he had withdrawn the offensive substance the insect 

 would continue to rub its antennae as if to remove the dis- 

 turbing odor. A sort of holding its nose. He then cut 

 off the antennae to find that the insect was now insensible 

 to the irritant. He next put food before the insects, which 

 was quickly found and appropriated; but after the antennas 

 were cut off the food was found with difficulty if at all. 

 Experiment showed that in mating the same was true. 



