26 ENTOMOLOGY. 



Patten: " The difference in vision is dne more to the powers 

 of association than to variation in the structure of the eye" 

 ("Eyes of Mollusks and Arthropoda," Naples, p. 699). 



It is now generally agreed that the olfactory organs are 

 situated in the antenna?. This has been experimentally 

 proved. When the antenna? of insects which show a decided 

 dislike to strong or disagreeable smells, such as the odor of 

 carbolic acid, oil of turpentine, or vinegar, are removed, 

 the actions of the insects operated upon show that they are 

 not affected by such smells; insects fond of decaying flesh 

 do not run or fly toward it when deprived of their antenna?, 

 nor are they, after losing their feelers, able to go to their 

 mates. As Forel says, in many insects which are guided by 

 sight, such as dragon-flies and cicada?, the antenna? are 

 minute, rudimentary, and do not have the sense of smell, 

 though the cicada may be guided by the sense of hearing. 



The organs of smell, according to Hauser, consist, in in- 

 sects, — i.e., all Orthoptera, Pseudoneuroptera (i.e., white 

 auts, Perla?, Psoci, dragon- and may-flies), Diptera, and 

 Hymenoptera, also in most Lepidoptera, Xeuroptera, and 

 Coleoptera, — 



1. Of a thick nerve arising from the brain which is sent 

 into the antenna'. 



2. Of a sensitive apparatus at the end, consisting of 

 staff-like cells, which are modified hypodermis cells, with 

 which the fibres of the nerves connect. 



3. Of a supporting ami accessory apparatus, consisting of 

 pits, or peg- or tooth-like projections filled with a serous 

 fluid, and which may be regarded as invaginations and out- 

 growths of the epidermis. These appear as microscopic 

 pits and teeth, usually situated at or near the end of the 

 antenna?. The number of these olfactory pits and projec- 

 tions is sometimes enormous. In the European cockchafer. 

 (Melolotitha vulgaris) 39,000 occur in the leaves of the male 

 antenna?, and about 35,000 in those of the female (Fig. 20). 

 In Vespa crabro each joint of the antenna (iiagellum) pos- 

 sesses between 1300 and 1400 pits, nearly GO teeth, and 



