4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 63 



now generally prevalent, that taste and smell are chemical senses, 

 while sight, hearing and touch are purely mechanical. 



Baster (1798), cited from Perris (1850), believes that olfactory 

 stimuli are received by the trache?e, either at their apertures or 

 throughout their whole extent. 



Lehmann (1799), according to Lacordaire (1838), was the first 

 who actually performed experiments to determine the location of the 

 olfactory apparatus. He made a round aperture, surrounded by wax, 

 in a glass bottle, in the center of which was a paper diaphragm. The 

 antennae or entire head of an insect was then inserted into this 

 aperture. He next introduced into the bottle strongly odoriferous 

 substances, such as burnt feathers, burning sulphur, etc. None of the 

 insects subjected to this test reacted, but when the same substances 

 were placed near the remaining part of the insect, the specimen made 

 violent movements which showed the effect these substances had upon 

 it. He concluded, therefore, that the head is not the seat of olfac- 

 tion and that it must lie in the tracheae near their external openings. 

 As the antennae are covered with hard chitin, while the tracheal walls 

 are clothed with very thin, chitinous membranes, critics contend that 

 such strong irritating odors mechanically irritate the tracheae and 

 that these odors cannot so affect the antennae on account of the hard 

 chitin. 



Cuvier (1805) thinks that since all other air-breathing animals 

 have the organs of smell located at the entrance of the respiratory 

 organs, we should find it at the entrance of the tracheae in insects, 

 as Baster suggested. He added that the internal membrane of the 

 tracheae, being moist, appears properly to fulfill this office, and that 

 in the insects in which the tracheae form numerous vesicles these 

 tracheae appear to be excellently suited for the seat of smell. The 

 antennae do not seem to fulfill any of these required conditions. 



Straus-Durckheim ( 1828) believed that the seat of olfaction is 

 located at the entrance of the tracheae because he discovered, in the 

 environs of the spiracles, nerves which are large enough to belong to 

 a special sense organ. 



Lacordaire (1838), after discussing the experiments of Huber and 

 Lehmann, says that from all the preceding we can conclude that we 

 know nothing positive about the seat of smell and that the hypothesis 

 which locates it in the respiratory organs is yet the most rational of 

 all. 



Brulle ( 1840), after briefly discussing the sense of smell in articu- 

 late animals, remarks that the organ of smell is not known in these 



