SCIENTIFIC NOTES ANP OBSERVATIONS. 207 



With regard to the points raised by Dr. Freer, I would point out 

 that there is a great deal of diflferenco in the colours of the fluid material 

 voided by different newly-emerged insects, and tliat they vary widely 

 in different specimens of the same species. Sometimes this variation 

 appears to be sexual, in other instances the fluid ap})ears to vary in the 

 intensity of its colour among different individuals, irrespective of sex. 

 Now that its connection with the pigment material in the wing has 

 been to a large extent demonstrated, and we know that unsatisfactory 

 conditions of health produce in some instances a partial failure in pig- 

 ment, it is forced upon one that this difference in tlie colour of the voided 

 material, is, in the same sex, to a large extent dependent upon the healthy 

 condition, or the reverse of tlie individual. I am satisfied that the colour 

 of the waste matter voided has but little direct connection with the colour 

 of the wings, because the fluid voided is of a briglit red in Aporia crataegi, 

 and we all know that there is no red in the colour of this species. I do 

 not know that the gorgeous butterflies, mentioned by Dr. Freer, inhabit, 

 in the way assumed, the " gloomy forests " of the Tropics. So far as my 

 reading has led me, I have always pictured those brilliant fellows as fly- 

 ing bird-like on the outskirts of the forests and above the tallest trees, 

 but rarely descending into the dim vistas beneath the arched canopy 

 formed by the interlacing foliage of the lofty crowns of the forest mon- 

 archs. In these dim shades a new insect world of duller-coloured 

 butterflies and moths exists, quite different from those of the outside 

 world which haunt the tree-tops above, or the open spaces of the forests. 

 The purjde of Thecia quercus and of Apatura iris is, I believe, largely due 

 to the diffractive action of the scales on light ; I do not understand in 

 what way they can be refractive. I am sorry to say that I know but little 

 of the distribution of Miselia oxt/acanthcu; var. capucina, even in the British 

 Isles. Strangely enough, I have never been able to get the variety from 

 my friends with sufiicient freedom to give even a guess at its British dis- 

 tribution. Staudinger, in his Catalog (1871), gives " England " as its 

 sole habitat. This I much doubt. I believe the metallic appearance of 

 certain parts of the wing of this species to be purely superficial. I 

 have a specimen which was in Coverdale's collection when I bought it, 

 among his " albinos " as he called them, in which the colour is almost 

 entirely gone, and yet, which shows the metallic portions of the wing 

 with something of a smooth glossy appearance, and I have a sjoecimen 

 of Pliifiia rhrysitis in which the pigment beneath the glossy patches is 

 practically nil, although the superficial gloss remains. In all these 

 species there is no doubt whatever that the glossy surface of the wing, 

 which gives certain })arts their metallic lustre, is entirely superficial, 

 and has no direct connection whatever with the colours which the lustrous 

 areas directly overlay. I could only give a speculative reason for my 

 opinion, but I have frequently advanced tlie supposition that capucina 

 was probably the ancestral form of this species. 



I have read Dr. Riding's theory as to change of colour in T. ruhi 

 under the influence of wetting, and must confess that it is by far the 

 most scientific explanation of the phenomenon yet brought forward. 

 It is, I suppose, reasonable to assume that if two coloured lights which 

 are complementary be reflected, one of which is in excess, that equal 

 quantities of the complementary colours would combine to form wliite 

 light whilst the excess would pass on to the eye and ultimately i)ro- 

 duce the colour impression of the object. 



