M. BORDAGE ON CHRYSALIDS. 235 



not to be the same in all the families, and sometimes in the 

 struggle for the upper hand between black and white for a certain 

 time, now one, now the other is uppermost. As to the whole 

 family of the Papilionidac, that of the Lycaenidae and the genus 

 Vanessa of the NympJialidae, I have no longer any doubt that 

 there the '^evolution of colour'' is the same as that of the Pieridae. 



The recognition of this evolution has still a deeper significance. 

 Through it a light is thrown on a number of phenomena hitherto 

 insufficiently explained ; such as on the melanism of the butterflies, 

 and also to some extent on their albinism ; on their polymorphism, 

 be this permanent or presenting itself as season-dimorphism (it 

 proves also the inaccuracy of the idea of it being caused by 

 heterogeny) ; on the variation of their colour among the individuals 

 or in the local races ; on the nature of the change brought about by 

 artificial temperature ; on the origin of " eye-spots," and other 

 phenomena. This gives a clue to much which is of importance 

 respecting heredity under the working of newly-arising influences ; 

 the phenomenon of mimicry is thus also better understood. And 

 lastly this knowledge throws a bright light on the fact that in this 

 evolution going on from time immemorial and gradually changing 

 a whole group of animals, natural selection (not even to speak of 

 sexual selection) plays no part at all. 



Truly, if I am not mistaken, and I do not think I am — but to 

 err is human — I may speak of a new view on the phenomena of 

 Lepidopterology and of a new field of investigation, which too is 

 not without importance for other branches of zoology. 



Now this new view it is my wish to introduce among the country- 

 men of Darwin ; for though it appears to be in opposition to 

 Darwinism in the latest and the narrowest sense, it is really a step 

 forwards in the domain of that evolutionism with which Darwin's 

 name and fame is incontestably associated. 



2. Experiences sur la relation qui existe entre la 

 couLEUR Du Milieu et la couleur des Chrysalides 



DE CERTAINS L£pIDOPT£RES. 



By M. Edmond Bordage, 



DlRECTEUR DU MuSEUM d'hISTOIRE NATURELLE DE l'IlE DE LA REUNION 



(Bourbon). 



Plusieurs observateurs ont signale la relation que Ton peut 

 constater entre la couleur des chrysalides de certains Lepidopteres 

 et celle des surfaces sur lesquelles elles sont fixees. Les recherches 

 les plus remarquables a ce sujet sont celles d'un eminent savant 

 anglais, Mr Edward B. Poulton, de la Societe Royale de Londres'. 



1 E. B. Poulton, An Enqiihy into the Cause and Extent of a special Colour-Relation 

 between certain exposed Lepidopterous Pupit and the Surfaces which immediately surround 

 them (Phil. Trans. Royal Society, 1887). Voir aussi : The Colours of Animals (1890), du 

 meine auteur. 



