58 COMPLEX STRUCTURE OF THE ANTENN^i:. 



are many modifications; for instance, complex pits 

 often arise from the confluence of several small ones. 

 The structure of the antennae is then very complex, and 

 increases with the importance of the antennae in the 

 life of the insect. Among the Hymenoptera, Lyda has 

 about 600 pits; Tenthredo, 1200; Sirex, 2000; Pompilus, 

 3000; Paniscus, 4000; Ichneumon, 5000; Hyloeus, 

 6000; the wasp (Vespa), about 13,000 pits and 700 

 cones ; the blowfly, 17,000 ; the hive bee, according to 

 Hicks, about 20,000 pits and 200 cones. Among beetles 

 (Coleoptera) the numbers are generally small, but the 

 cockchafer (Melolontha) possesses, according to Hauser, 

 on each antenna as many as 35,000 in the female, and 

 39,000 in the male. Moreover, it is significant that in 

 those species where the females are quiescent and are 

 actively sought out by the males, the antennae are 

 much less highly developed in the female sex than in 

 the male. 



As already mentioned, the antennae probably serve 

 partly as organs of touch, and in some cases for smell. 



On the other hand, I do not believe that touch and 

 smell are the only two senses possessed by the antennae. 

 Forel and I have shown that in the bee the sense of 

 smell is by no means very highly developed. Yet 

 their antenna is one of those most highly organized. 

 It possesses, as I have just mentioned, besides 200 

 cones, which may probably serve for smell, as many as 

 20,000 pits; and it w^ould certainly seem unlikely 

 that an organization so exceptionally rich should solely 

 serve for a sense so slightly developed. 



Much as these antennal structures differ from one 

 another in form, arrangement, and structure, they are 

 all reducible to one type — to a hair — more or less de- 



