16 [June, 



the " Canadican Entomologist " for this year, in which he records experiments upon 

 IPhyciodes Tharos, a polymorphic butterfly. — F. Buchanan White, Perth : 

 April, 1877. 



Melanism in LepidojHera. — After Mr. Bircliall's and Dr. Buchanan "VMiite's 

 notes on this subject (vol. xiii, pp. 130 and 145), and the very feasible explanation 

 the theory of natural selection gives of the prevalence (though not the cause) of 

 these dart varieties, I was somewhat surprised to see what may be called the "birth- 

 mark " theory revived to account for them by Mr. Fetherstonhaugh (p. 215), and 

 subsequently supported by Mr. Tugwell (p. 256). It is almost impossible to one 

 liaving any physiological knowledge to see how any impression on the sensorium of 

 the parent can produce any permanent change (except perhaps a deficiency in some 

 parts) in the structure of its offspring. As, however, one fact is worth a hundred 

 theories, I may perhaps be allowed to quote here a passage from Darwin's " Animals 

 and Plants under Domestication" (Ist edit., vol. ii, p. 263), which seems to me to 

 be decidedly " ad rem," as regards the subject under discussion. He says " it was for- 

 merly a common belief, still held by some persons, that the imagination of the 

 mother affects the child in the womb. * * * Dr. William Hunter, in the last 

 century, told my father that during many years every woman in a large London 

 lying-in hospital was asked before her confinement whether anything had specially 

 affected her mind, and the answer was written down : and it so happened thai in no 

 one instance could a coincidence be detected between the toomans answer and any 

 abnormal structure ; but when she knew the uatui'e of the structm-e, she frequently 

 suggested some fresh cause !" Natural selection perfectly explains the facts adduced 

 by Mr. Tugwell about Gnophos obscuraria, for of course on a dark soil the darker 

 individuals, on the light the lighter ones, will be best protected by their colours and 

 will therefore have a better chance of escaping the notice of their enemies. That 

 the dark colour of the soil can hardly be the true cause in producing these variations 

 is, I think, pretty certain, from their occurrence in many places where the soil is not 

 conspicuously dark, e.g. the Highlands of Scotland and the Alps.* I have just been 

 looking through Dr. Staudinger's catalogue, and was much struck by the fact that 

 in nearly every case where a local form (whether a " var." or "ab.") from the Alps 

 is noticed, it is characterised as being " obscurior," or " multo obscurior," or with 

 some of the markings " obsoleta." The great number of normally dark or black 

 species of Lepidoptera in the Alps, as, for instance, the JErebicB, Psodos, and some 

 Fyralides {cf. Jordan, vol. xiii, p. 60), seems to me also to be worth notice in connection 

 with this subject. In a few cases, Alpine insects are only sexually melanic, e.g. Pieris 

 napi, $ , var. bryonice, A. Paphia, $ , var. Valezina, Polyommatus cirgaureae, $ , var. 

 Zermattensis. These cases are explicable, on the theory, that supposing sexual 

 selection to have been such an efficient agent in modifying species as Mr. Darwin 

 believes, it may have been more important for the males in the struggle for life to 

 preserve their good looks than to have acquired sounder constitutions at the expense 

 of the former. That the prime agent in this tendency to melanism is some unfavour- 

 able meteorological element, probably connected with an excess of moisture and 

 reduced amount of sunshine, is strongly suggested by the fact that, as noticed by 



* Conversely, too, one would expect, if this theory were true, to find more melanic vars. on 

 the very dark soil of pcat-uiosses and feu-lands, than i.s actually the case. 



