38 EXPERIMENTS. 



The oldest experiments of importance are those of 

 Lehmann. He bored holes through bottles, and then 

 inserted into them the abdomen of various insects, filling 

 up the interspace with wax, and leaving the head and 

 thorax outside. He then introduced into the bottle 

 various powerfal odors, such as burnt feathers, assafoe- 

 tida, burnt sulphur, etc., and as these caused obvious 

 movements of the body, he concluded that the insects 

 perceived the smell by the membrane surrounding the 

 tracheae. The facts have been verified by subsequent 

 observers, and are themselves doubtless correct. They 

 do not, however, prove Lehmann's case, for similar fumes 

 would, as Duges and Ferris justly observe, produce an 

 irritation in our throat, where there is certainly no 

 sense of smell. On the other hand, when substances 

 which have no such irritating properties are used, as, 

 for instance, honey in the case of a bee, decaying meat 

 with a carrion-eating beetle (Silpha), and so on, no re- 

 action has been perceived. On the whole, experiments 

 lend no countenance to Sulzer's theory (see p. 35), 

 and, in the absence also of any anatomical evidence 

 in its support, it has, I believe, now no advocates. 



I pass, then, to the second theory — that which 

 considers that the organ of smell is situated in the 

 mouth parts, either in the mouth itself according to 

 some authors, or the palpi according to others. We 

 have, I think, no clear evidence that the mouth itself 

 possesses any organ of smell. Huber, however, observed 

 that while, if he brought close to the mouth of bees 

 substances which were repulsive, or others which 

 were acceptable to them, such as honey, they were evi- 

 dently affected ; this w^as, on the other hand, no longer 

 the case if the mouth parts were stopped up with paste. 



