AROMATIC BUTTERFLIES 175 



of the same kind has been disclosed from its cocoon 

 entirely out of sight of and often at a great dis- 

 tance from her visitors. It is plain that in in- 

 stances of this sort, known to every entomologist 

 and too numerous to mention, the sense of smeU 

 must be the sole directing agent ; and since in 

 many of these instances no odor is perceptible to 

 human sense, it is plain that there may be many 

 odors emitted which, though imperceptible to us, 

 may be all-sufficient for them. This abundantly 

 explains the many cases of organs from which 

 we can perceive no odor, when in alHed insects 

 identical organs are perceptibly fragrant. 



Moreover, we have in certain specific structures 

 in the enlarged antennal club of butterflies what 

 are plainly sense-organs supplied with nerve-end- 

 inos ; and inasmuch as there is no structure found 

 in them which could subserve the purpose of hear- 

 ing, or indeed of any other of the senses known to 

 us excepting that of smell, it is the belief of physi- 

 ologists that here are situated the organs of smell 

 in butterflies. The under surface of the antennae 

 of butterflies is invariably naked to a greater or 

 less degree, and, more plainly in some joints than 

 in others, little dimples can be readily seen. It 

 is in these little pits that are situated the organs of 



