138 tHE ENTO]VfOLO(ilST. 



neither red hor yellow, but blue — a physical colour. This 

 appears, at first sight, a rather grave difficulty, but it is lessened con- 

 siderably by the fact that the one blue band offraxini is not in the 

 same position as the bands of, e. g., C. nupta, but is in a position in- 

 termediate between these. More difficult to understand, however, is 

 the case of a species of Vanessa * which. I recently saw in Mr. Leech's 

 collection. In this species the (pigmental) red of V. atalanta was 

 represented by a blue, that, judging from its appearance, I should 

 say was certainly physical. Finally, it has lately been stated, by 

 Dr. Seitz.t that in a restricted woodland area in S. Brazil the 

 great majority of the insects (not Lepidoptera only) were blue; 

 whilst, only a few miles off, red was dominant. This appears to 

 me — taking the statement to be correct — strongly indicative of a 

 blue pigment, produced by some chemical difference in the 

 district. If this be so, it is certainly strange that among so many 

 different families examined I should have found no blue pigment ; 

 and I can only say that I should greatly like to experiment on 

 some of those species referred to by Dr. Seitz. 



Now for the relations of the colours. Black and white of 

 course are out of court altogether; so is blue, since even if the 

 Lycsenidse should turn out to be pigmental, it is impossible, in 

 the present state of our knowledge, to bring this blue, reverting to 

 slate colour or grey, into any genetic relation with the other 

 colours. There remain, then, red (including pink) ; yellow, in 

 all its modifications ; chestnut, also in various modifications ; and 

 the (pigmental) greens. Now the facts known to us are these :— 

 Orange and red and pink are developed from yellow ; a few reds 

 are developed from chestnut ; chestnut and yellow are very closely 

 allied indeed in constitution, indeed it is difficult to draw any 

 definite line of demarcation between some chestnuts and some 

 yellows ; green is, not improbably, also developed from yellow, 

 although of this it is not possible to speak certainly at present. 

 Finally, we may have such a thing as a latent yellow pigment, as 

 demonstrated by the phenomenon of A. galatea. These facts I 

 have sought to bring together, in an easily grasped graphic form, 

 by means of the accompanying genealogical tree. It does not 

 appear to' me to involve much unproven theory, except as regards 

 the assumption that the different stems start from one original 

 pigment molecule, which, for the sake of a concrete illustration, 

 I have called "galatea" stage. This illustration, it will be 

 understood, is adopted only for the sake of plainly grouping all 

 the facts together. It involves, however, very little trespass 

 beyond our known facts. In partial defence of it, I might 

 perhaps point out that galatea, which we know does possess a 

 " pigment mother substance " convertible to yellow, is very 

 closely allied, entomologically, to the various genera of Satyridae, 



* Vanessa charonia, DrU. (Ed.) 



t ' Zoolog. Jahrb.,' v. (1890) ; quoted id ' Microscopic See. JI.,' 1890, p. 712, 



