260 STATES OF INSECTS. 



Aurelia were applied to the whole. The alchemists mis- 

 took this for real gold ; and referred to the case as an 

 argument in favour of the transmutation of metals. But 

 Reaumur has satisfactorily shown, that in this instance 

 the old proverb is strictly applicable — " AH is not gold 

 that glitters." He found that this appearance is owing 

 to the shining white membrane immediately below the 

 outer skin, which being of a transparent yellow gives a 

 golden tinge to the former ; in the same way that tinfoil, 

 when covered with a yellow varnish, assumes the metallic 

 appearance which we see in gilt leather. He mentions, 

 too, that for the production of this effect — it is essential 

 that the inner membrane be moist: whence may be ex- 

 plained the disappearance of the gilding as soon as the 

 butterfly is ready to escape from the pupa. The shade 

 of colour in these gilded chrysalises is various: some are 

 of a rich yellow, like pure gold; others much paler; and 

 some nearly as w T hite as silver. That of Hipparchia 

 Cassia F. is red with silver spots a . 



Though by far the greater number of the chrysalises 



of moths are of an uniform chestnut, brown, or black, 



a few are of other colours ; as that of Geometra alhiaria. 

 which is of a glaucous blue; of Noctua sponsa, lilac; and 

 of Noctua pacta, of a lovely blue, caused by a kind of 

 bloom, like that of a plum, spread upon a brown ground. 

 A similar bloom is found on that of Parnassius Apollo, 

 and on the anterior part of that of Platypterix cultaria 

 and sicula ; in which last, Kliemann observed it to the 



a Ins. Surinam, t. xxxii. Lister imitated the gilding of Chrysalises 

 by putting a small piece of a black gall in a strong decoction of net- 

 tles : this produced a scum, which when left on cup-paper, he says, 

 will exquisitely gild it.— Ray's Letters, 87. DO. 



