88 



THE ENTOMOLOGIST. 



thus distinguish several (say three) different stages or planes in 

 chestnut also, and that in the highest (most stable), it is at 

 present not possible to determine certainly whether we are 

 dealing with a " physical," or with a very stable, pigment colour. 

 And, finally, that in chestnut, also, a very marked advance in 

 brilliancy of colour may take place without a concomitant increase 

 in stability (i. e., decrease in solubility). This latter, as already 

 stated, I consider to be of the nature of a collateral advance, not 

 a stage in the main-stream of coloric evolution. 



2. — That chestnut, as well as yellow, may evolve into a red. 



On the other hand, several differences must be noted : — 



1. That the concomitance of increased brilliancy, or depth of 

 colour with increased stability (insolubility), is by no means so 

 clear (if, indeed, it can be legitimately maintained at all) in 

 chestnut as in yellow; and, on the other hand, the "collateral" 

 brilliant, but soluble, colours appear far more common in 

 chestnut than in yellow. 



2. — That the advance to red, which is so common among 

 j^ellows, is very rare among chestnuts ; though why this should 

 be so — considering, especially, how brilliant a colour has been 

 evolved in the case of atalanta — is by no means clear. 



Let us now arrange the various chestnut* species in three 

 divisions, corresponding with those of yellow : — 



3. Unaffected. 



2. Intermediate ; 

 somewhat affected. 



1a. Brilliant; 

 but soluble easily. 



1. Soluble easily. 



Orgyia antiqua 



Melitcea athalia 



Vanessa io 



Vanessa cardui 



Bombyx querais 

 Orthosia inacilenta 



Epinephele tithonus 

 Satyrus megcera 



V. antiopa 

 V. urticcB 



Argynnis paphia 

 A. selene 



Mamestra oleracea 

 Cidaria auffuviata 

 Coreniia ferrugata 

 C. munitata 



Atliyma penus 

 and perhaps 

 E. ianira 



Polyomviatus 



phlceas 

 P. virgaurea 



Coenonympha 

 pamphilus 

 Hesperia sylvanus 

 Danais chrysippus 



Eumia cratcegata 

 Phalera bucephala 



and perhaps 

 Limenitis sibylla 





t 



D. hegesippus 

 t 



Several interesting points are brought out by this tabulation. 

 First of all, it is to be noted that, with one doubtful exception, 

 no Rhopalocera are to be found in No. 3 column, and no Heterocera 

 in the others. Whether this distinction will hold good when 

 larger numbers of species come to be examined, it is, of course, 

 as yet, impossible to say. And in this connection we must note, 

 also, another point, viz., that among the yellows several of the 

 species placed in the " unaffected " column were known (by other 

 reactions or by their relationships) to be certainly pigmented 



* See Entom. xxiii. pp. 221 and 250. 



t Note that alkalis seem considerably more efficacious, on the whole, than 

 acids in dissolving chestnut. See Entom. xxiii., p. 250. 



