AROMATIC BUTTERFLIES 173 



described by Fritz Miiller. But if the species of 

 Oeneis named possesses this odor in both sexes, it 

 is probable that it does not arise from the scent 

 scales but from some other source, probably from 

 some abdominal excretory organ, such as Miiller 

 has described in many other butterflies. I have 

 been unable to detect any odor in three other spe- 

 cies of Oeneis examined alive by me, and they, like 

 Mancipium brassicae, are merely some of many 

 instances in which our senses cannot perceive an 

 odor presumably emitted. Lelievre, again, found 

 that both sexes of Thais polyxena had on eclosion, 

 when handled, an odor similar to that of its food 

 plant Aristolochia, the odor arising from a fluid 

 which was left upon the hand that had seized the 

 insect. The European Swallow-tail (Papilio ma- 

 chaon) is also said to sometimes exhale a distinct 

 odor of fennel, upon which, the larva feeds. All 

 these, however, are plainly means of defense, if 

 they have any purpose, and have no relation to the 

 odors of scent scales. Nor does it appear that any 

 organs for their production have been noted. 



The statement by Miiller that the fragrant odors 

 emitted by butterflies are in some cases produced 

 by peculiar scales found in the male sex, and which 

 he terms scent scales, was received with a great 



