84 Mr. F. A. Dixey [March 8, 



Now, granted that the avoidance of attack by birds is the object of 

 the repulsive scents, we should, of course, expect to find them present 

 not in one sex only, but in both alike. And this is precisely what we 

 do find ; moreover, since it is well recognised that the preservation of 

 the life of the female is more important than that of the male for the 

 welfare of the species, we should expect that if there is a difference 

 ])et\veen the sexes in the intensity of the odour, that difference would 

 be in favour of the female. This, again, is borne out by observation 

 in a number of cases. AVhere both sexes are repulsive, the female, as 

 a rule, is the more repulsive of the two, and therefore (as a consola- 

 tion) the safer from attack. 



So much for the odours unpleasant. Now let us turn to the 

 other kind, the fragrant flower-like perfumes with which we dealt at 

 the outset. These, we saw, are frequently associated with specialised 

 scales which are the exclusive property of the male sex. We cannot 

 say quite so much for the odours themselves, for though in the great 

 majority of cases they belong to the males alone, yet the females are 

 not left entirely destitute. Fritz Miiller many years ago found evi- 

 dence of sweet scent in a female white butterfly, and since then Dr. 

 Longstaff has detected in the females of several species a fragrance 

 not unlike that of the male, but usually much weaker. Still, we may 

 certainly say, speaking generally, that the pleasant odours show a vast 

 preponderance in favour of the male. This suggests that they must 

 have some significance in regard to the relations between the sexes, 

 and, indeed, there can be little or no doubt that, as was first pointed 

 out by Fritz Miiller, these scents are employed by the males in court- 

 ship as a means of attraction ; they may also perhaps serve as a means 

 of recognition. That their employment is occasional, and not constant, 

 appears from the fact that they are so often furnished with a provision 

 for keeping them confined until wanted. There is, so fai- as I am 

 aware, no direct evidence that they are more plentifully liberated 

 during courtship ; but to any one who has observed the persistent 

 ffuttering of white butterflies about and around each other under 

 those circumstances, it can hardly fail to occur that the fanning wing- 

 movements of the male must have the effect of encouraging the evapor- 

 ation and diffusion of the odour ; also perhaps of aiding it escape from 

 the disc through the footstalk and so into the lamina of the plume- 

 scale. The flowery scents would thus come under the head of those 

 features which have been called by Professor Poulton " epigamic ; " 

 characters, that is, which, like the splendid plumage of some cock-birds, 

 are believed to further the cause of matrimony. If this interpreta- 

 tion be correct, it is most interesting to find that the esthetic prefer- 

 ences of butterflies in the matter of scents are so much like our own. 

 In other insects, as well as in many of the higher animals, we find 

 attraction exercised by odours that to our senses are disgusting. 

 Butterflies themselves are not exempt from a depraved taste where 

 food is concerned ; the best bait for the Purple Emperor is well 



