484 PHYSIOLOGY. 



partly from the deficiency of a satisfactory proof of a different function 

 of the organ. Thus we recognised in the palpi organs of touch, in the 

 tongue the seat of taste, in the mucous membrane of the tracheee the 

 sense of smell, and in the antennae, lastly, we discovered the instru- 

 ments of hearing. The mode whereby the insect receives perceptions 

 through these organs will certainly not divaricate from that found in 

 the superior animals. Touch, taste, and smell require the direct appli- 

 cation of the investigating organs to the investigated object, and so 

 soon as this takes place the insect perceives. We have convinced our- 

 selves by experiment that an insect feels objects all over with its palpi 

 which it wishes to inspect for food or other purposes, but that the 

 tongue tastes, and the mucous tunic of the tracheae smells, can only be 

 made probable. With respect to the latter, it is contradictory to the 

 views of very learned naturalists, namely, Kirby and Spence * and 

 Treviranus, who both adopt as the organ of the sense of smell a pecu- 

 liar one standing in connexion with the mucous tunic of the mouth. 

 With respect to its situation above the mouth, it has certainly the 

 analogy of all the other animal classes in favour of it, and their opinion 

 would even on that account merit entire approbation if absolutely the 

 organ of which these authors speak could there be found. But this is 

 not the case, and even Treviranus convinced himself by multitude of 

 experiments of its absolute deficiency, and so suggested the opinion that 

 the mucous tunic of the mouth was likewise the organ of smell, and 

 that therefore the sense of smell was especially to be ascribed to haus- 

 tellate insects only. Kirby and Spence, however, to whom the striking 

 contrary proof exhibited in the extremely keen smell of the bury- 

 ing beetle was probably present, decide absolutely in favour of a 

 peculiar organ of this sense, lying beneath the clypeus, and which 

 they call the nose, and which borders upon the mucous tunic of the 

 mouth. In the burying beetle they say they have discovered this organ 

 in the form of two circular fleshy cushions, which are covered by a beau- 

 tiful and finely transversely striped membrane; the same also in 

 Dyticus marginalis, in which it is further provided with a pair of 

 warts ; as also in (Eschna viatica. But the investigations of other 

 anatomists do not confirm these discoveries. If such an organ really 

 existed at the spot indicated, Straus would certainly have seen it in the 

 cockchafer; and I believe I may assert, that in several endeavours 



* Introduct. to Kntom. iv. Letter xlv. 



