Sensory Discrimination: The Chemical Sense 93 



lay their eggs have been taken as evidence of the smell 

 function of these organs (574). Mclndoo (455, 456, 457, 

 458), however, has recently presented evidence against 

 the olfactory function of the antennae. His experiments 

 were performed on beetles, ants, honey bees, and hornets. 

 His line of argument is as follows. While it is true that 

 insects whose antennae have been removed fail to respond 

 normally to odors, this is because such insects are abnormal 

 in all their behavior. There exist in various regions of 

 the body of insects, as for instance the bases of the wings 

 and legs, small pores containing sense cells ; these Mclndoo 

 calls olfactory pores. He finds by measuring the time 

 required for insects to respond to odors, that this reaction 

 time is lengthened more decidedly when the olfactory 

 pores are varnished over than when the antennae are 

 removed. 



The function of the chemical sense in the mating processes 

 of insects is one of the most remarkable phenomena con- 

 nected with the sensory reactions of animals. Forel says 

 he had a female Satumia moth shut up in his city room, 

 and that within a short time a number of males came and 

 beat against the window (231). Riley hatched in Chicago 

 some moths from the Ailanthus silkworm, which were 

 carefully confined. No other specimens were known to 

 exist within hundreds of miles. A virgin female was put 

 in a wicker cage on an ailanthus tree, and a male, with a 

 silk thread tied around the abdomen for identification, 

 was liberated a naile and a half away. The next morning 

 the two were together (637). 



The most interesting observations on the sense of smell 

 as used in the mating of insects, however, are those of 

 Fabre. A cocoon of the "Bombyx du ckene," a species of 

 which Fabre had not seen a specimen in the locality for 



