AXTENN.E OF LEPIDOl'TKUA. 11 



6. There is another set of nervous appuratus whicli, though it 

 cannot aftbrd any taxononiic characters, at least not without invol- 

 ving the careful preparation of difficult sections, may throw some 

 light on the question of function. It is always situated in the pedi- 

 cel. Fig. 19 represents a section through the apparatus in the an- 

 tenna of a male Callosamia 2}roviethea. It is a sagittal section of 

 the ventral half of the pedicel, with parts of the adjacent segments ; 

 but the apparatus extends around the whole segment, so that a lon- 

 gisection in any plane would present essentially the same appear- 

 ance. As the antennal nerve-trunk enters the pedicel, it gives off 

 on all sides nuiiierous branches, which extend peripherad. When 

 it approaches the outer wall each nerve bends distad and joins a 

 nerve-cell with a distinct nucleus. Extending distad from the cell 

 is a long, slender rod with one or more nucleal bodies. These rods 

 are gathered into small conical bundles and terminate within pores 

 situated in the mend)ranous ring which connects the chitinized walls 

 of the pedicel and the proximal joint of the clavola. It will be 

 remembered that the base is the movable part of the antenna ; while 

 the clavola, except in case of the application of external force, is as 

 one piece. It at once becomes evident that any movement of the 

 clavola upon the base, whether due to its contact with some object 

 or to a vibration caused by a vibration in the air, would be at once 

 felt in the membrane in which these rods lie. As there are rods in 

 every part of this membrane a definite impression of the movement 

 would be produced in the sense-rods. 



FUNCTION. 



That the antenna) function as organs of s])ecial sense there can be 

 no question. Just what the sense, or senses, may be, we cannot tell, 

 but we may ai)proxiinate the true character. When we consider 

 how little we know of the essential operations which accompany our 

 own perceptions, we nnist realize the difficulty of the i)roblem. We 

 can form definite ideas of what sensations are possible to insects 

 mainly by interpretations of physiological action and of histological 

 structure, as conqoared with similar actions and structures in our- 

 selves and in the higher animals. Doubtless the range of perception 

 in insects is widely different from our own ; yet, that there must be 

 considerable similarity in the organs, fidlows from the fact that the 

 external substances or forces nmst work through the same media in 

 both cases. 



TRANS. AM. ENT. SOC. XXIII. JANUARY, 1896. 



