444 THE ZOOLOGIST. 



Illustrations of Demonstrated Mimicry. 



Butterflies of other families are found as mimics of the 

 Danaidce and Heliconiidce, which have been shown to be generally 

 uneatable, and avoided by Birds, Dragonflies, Lizards, and other 

 enemies. The fact that the writer found a Danais chrysippus 

 being devoured by an orthopterous insect (Hemisaga prcedatoria)* 

 is only another illustration of the much used motto — the excep- 

 tion proves the rule. The glands near the anus of some Heli- 

 coniidce have also been proved to emit a pungent odour. These 

 facts have been recorded by Bates, Belt, Trimen, Wallace, and 

 others. But Mr. Frank Finn, who has made some careful ex- 

 periments to test the " Theory of Warning Colours and Mimicry," 

 certainly found that his birds in captivity not only ate, but some- 

 times seemed to prefer, specimens of Danais and Euploea. Never- 

 theless, when he experimented with birds at liberty, he had not 

 the slightest doubt " as to the unpalatability of Danais, and the 

 other ' warningly-coloured ' forms. Birds would often look at 

 them, and soon left them when picked up." But when he further 

 experimented with the common garden Lizard of India (Calotes 

 versicolor), he came to the conclusion that " the behaviour of 

 these reptiles certainly does not appear to afford support to the 

 belief that the butterflies at any rate, usually considered nauseous, 

 are distasteful to them."f 



Miss Newbigin is also a sceptic on this point, based on her 

 physiological study of animal colouration. She remarks : — 

 " Instead therefore of supposing that the Heliconiidce have, in 

 Mr. Wallace's words, ' acquired lazy habits ' and a slow flight 

 because they are uneatable, and the Pieridce because they resemble 

 the Heliconiidce, may we not rather suppose that the slow flight and 

 1 warning ' colours in both cases are due to the same cause, the rela- 

 tively low organisation which renders pigmentation by waste pro- 

 ducts possible, which makes brilliant optical colours impossible ? "J 

 As appertaining to this subject, Mr. Hopkins has demonstrated 

 the presence of uric acid in the wing-pigments of the Pieridce, 

 and observes : — " The described uric acid derivatives, though 



* '• A Naturalist in the Transvaal,' p. 65. 



f Of. J. A. S. Bengal (Nat. Hist.), vol. lxiv. pp. 344-56 ; and vol. lxv. 

 pp. 42-8. 



% ' Colour in Nature,' pp. 161-2. 



