HARDWICKE'S SCIENCE-GOSSIP. 



87 



caterpillars, save that that of the small white is the 

 greater coward, for stretching its prolegs backwards 

 you will frequently observe it reposing flat on the 

 cabbage leaf, while that of the green vein walks with 

 head erect contemplating the sky. After this stage, 

 the caterpillar of the small white commonly acquires 

 some orange in the clear line along its back, and an 

 orange speck on and behind its spiracles. In this 

 country the small white butterfly is white or pale buff, 

 and the yellow on the under-side is buff or canary 

 yellow ; it has also its pale spring and darker summer 

 brood, differing in the amount of black marking 

 which needs the midsummer sun for its full develop- 

 ment. Perhaps the buff coloured variety, which is not 

 the result of any especial food, is commoner in spring. 

 The green vein varies in precisely the same manner ; 

 but I have never noticed the under-surface of the 

 hinder wings buff in this country. In Lombardy, 

 where we meet with larger races of butterflies, the 

 green vein may be found with a buff under-surface to 

 the hinder wings ; and this form so nearly approaches 

 the small whites of southern Europe, that no disciple 

 of Linnaeus could with any confidence say to what 

 species a white butterfly from that portion of the 

 globe should be referred. 



But to trace the ancestry of the white butterflies, I 

 would as soon go east as south. On reading the 

 Entomologist's Monthly Magazine, for September, 

 1883, my eye was caught by a paragraph by Mr. H. 

 Pryer stating that he had bred from eggs laid by P. 

 napi many specimens of a summer brood that proved 

 to be the P. Mekte, hitherto considered a distinct 

 species of butterfly. I wrote to Mr. Pryer in Japan, 

 and he had the kindness to forward me, through Mr. 

 Janson, quite a series of Japan whites, the oriental 

 races of our small white and green vein. But, as I 

 said before, the butterflies and moths we knew in our 

 school days are giants when we see them come from 

 Japan. The climate of the south of Europe adds a 

 good quarter of an inch to the wing expanse of the 

 green vein, which becomes three-quarters of an inch 

 when we arrive at Japan, and these larger forms have 

 the same buff colour on the under-surface of the 

 hinder wings. In Japan, as in England, the spring 

 variety (Megamera) is more or less immaculate above, 

 and beneath the hinder wings the veins are strongly 

 chalked ; while the summer variety (^Melete) is a 

 counterpart of our dusky summer form : Science- 

 Gossip, for iS8j, p. 221, d). The spring variety 

 appears from March to April, the summer variety 

 from May to August. (See Mr. Pryer's paper. Trans. 

 Ent. Soc. Lond. 1882, p. 48.) In England the 

 dark female green veins appear in May and June, and 

 I fancy they result from a retardation in the develop- 

 ment of the butterfly in the chrysalis stage, and a 

 consequent greater exposure to the photographic 

 action of light. With regard to the small white 

 butterfly in Japan (var. crucivora), the female is a 

 little dark, as it is sometimes with us in summer (but 



perhaps there is also a spring variety), it is a trifle 

 larger, but does not differ in marking from those of 

 our own cabbage beds ; it is a swarthy race. The 

 big cabbage white, which I believe every physiologist 

 will recognise in India, despite an idea to rebaptise 

 it, has been thought likewise to extend to Japan 

 (Proc. Zool. Soc. 15 Nov. 1SS1), but Mr. Pryer has 

 not noticed it there. 



Now, somewhat for microscopists, who will find ia 

 insect physiology plenty of wonderful research. Let 

 any one hold a white butterfly from Japan to the 

 light, and a play of yellow radiance kindles on the 

 wings like the glare of a lamp, or the hue that falls 

 on Alpine snow at sunset. This tincture of a warmer 

 sky, peculiar to white butterflies in the east, is owing 

 to the scales lying in even rows on the wings so as to- 

 throw alternate, distinct lines of reflection ; whereas 

 on the wings of our ill-fledged kinds, light grows as 

 confused as it does on ground glass and sea foam. 

 Nor can I doubt but that these muslin wings, shimmer- 

 ing with golden tinsel, are the delight of ardent eyes, 

 on the sunburnt meadows of Japan, just as the little 

 striations along the plumes of a male purple emperor 

 bathe the forest gloom in lovely blue light that blinds- 

 the diamond insect eye with all the fascination of the 

 prism. To produce these beautiful colours all that is 

 required is a smooth evenly striated surface. My 

 bookbinder has bound my last volumes of Science- 

 Gossip in a lively blue that retains its gloss, the 

 surface of the cover being covered with minute beading.. 

 When I hold the cover away from the light it is blue, 

 when I place it against the light it is orange. Seen 

 nearer, the little beads have their shady side blue, and 

 their bright side orange, a matter which fairly puzzled 

 an old writer in the " Insecten Belustigung," who 

 appears to have supposed that the notches along the 

 scales of the purple emperors had their two surfaces- 

 differently coloured. But any object that absorbs blue 

 rays, as a white butterfly with a tinge of blue, or a 

 butterfly, more intensely blue, must, if it be a good 

 reflector, reflect the complementary colour, and an 

 orange butterfly the reverse. Some call the natural 

 colour chemical, and the other the dioptric ; if so the 

 white butterflies in Japan have a dioptric light. Could 

 we not apply the matter to increase the light of our 

 lighthouses, and make them dioptrics ? On the sugges- 

 tion of a leaf-cricket, I once thought a file attached 

 to a drum and fiddled on would make a good fog 

 signal, but a mechanical friend said it would never 

 hold its own with the steam whistle. 



On February 5th, the Duke of Westminster laid 

 the foundation stone of the new Chester Museum, 

 which is "intended for teaching, for study, and for 

 exhibition." Readers of the life of Charles Kingsley 

 and of "Town Geology" will hardly need to be 

 reminded of the interest he took in the Chester 

 Natural History Society. 



