384 DR. J. B. HICKS ON THE ORGANS 



horny organ, displaying no nerve upon its surface, cannot possibly be the instrument of 

 smell, for we always find in the olfactory organs a soft, moist mucous membrane fur- 

 nished with niuuerous nerves. No such tunic is to be found in insects, at least in their 

 head, or upon the surface of their bodies." 



Robineau Desvoidy (see Ray Society vol. for 1845) considers there is still doubt on the 

 the point. " He has already shown, in year 1827, that in the Crabs, as the outer antennae 

 are evidently the seat of hearing, so the inner ones are the seat of smelling ; and afterwards 

 proved, in his ' Recherches sur I'organisation vert^brale des Crustac^s, des Arachnides, 

 ft des Insectes,' 1828, that in the Isopodes the sense of hearing is no longer doubtful ; 

 in the Ai'achnides it is wanting, while, on the other hand, the parts pointed out as the 

 mandibles are here organs of smelling, and the poison-canal in them corresponds to the 

 laciymal passage of the higher animals. In the Insects the antennae are organs of 

 smelling, and usually also of tovicb. They have no organs of hearing at all." 



Kiister (see Ray Society vol. for 1847, p. 306) assigns to the feelers (antennae) of 

 insects the function of smelling. In some experiments with turpentine in glass tubes 

 the reporter says, " If these experiments show that the feelers betray a sensibility to the 

 effect of powerful odours, it is not yet proved that these act on them directly ; and so the 

 evidence that the sense of smell has its seat in the feelers is defective." 



Newport has given us a valuable paper on the use of the antennae of insects, in the 

 ' Transactions of the Entomological Society,' vol. ii. p. 229 (read in 1838, but prepared in 

 1831). He examined the antennae of Ichneumon Atropos ; he found all the joints, except 

 the second, perforated all arovmd by very minute holes. This, he says, is the structure of 

 nearly all the setaceous antennae. He observed two tracheae passing up its whole length, 

 which gave off branches at every joint, and which seemed to him — but of that he was not 

 quite certain — to communicate with the holes in the antenna-wall. He also noticed a 

 nerve passing throughout its length. 



From this, and from analogy with other animals, he judged it probable that the antennae 

 were not organs of smell. He instituted a series of interesting experiments which led 

 to the same conclusion, and mentions that " Co/jris Molossus" when in motion, ex- 

 tends the plates on the end of its antenna, as if to direct the insect in its course ; but 

 that on the occurrence of any loud and sudden sound, it instantly closes the plates and 

 retracts the antennae, as if injured by the percussion, while the insect stops and assumes 

 the appearance of death. The Geotrupides also behave in like manner. He says, " In 

 conclusion, from all that has been observed of the antennae, it seems probable that in all 

 insects these are the auditory organs, and that the means by which they are fitted for the 

 function of hearing are varied in different insects, to adapt them to the perception of 

 soimds, according to the habits of the species ; that in some species they are endowed 

 also with the sense of touch ; that they are of great, although not of vital importance to 

 the insect ; and that the loss of both of them, more particularly when endowed also with 

 the sense of touch, will clearly explain in every instance the agitation, delirium, or stupor 

 of the insect, it being in fact tantamount to a total deprivation of the faculty of hearing, 

 feeling, and, I might almost add, of speaking." 



The most advanced investigations into the anatomy of the antennae I had met with, on 



