﻿CHEMISTRY OF INSECT COLOURS. 221 



As a matter of convenience, in publishing, we will reserve the 

 tables of results in yellow, red, chestnut, blue, and green, until next 

 month (although naturally they follow on here), and take the 

 results afforded by the remaining and far less important colours. 

 First as to broivn. This class is really intended as a sort of 

 appendix to chestnut ; for under the latter term are included all 

 brown or chestnut colours that are affected by my reagents, 

 whilst as brown are grouped together all the " indifferentists." 

 It is, perforce, a somewhat heterogeneous assemblage, including 

 many different browns, and two or three odd chocolates that I 

 hardly knew how to dispose of, and therefore finally grouped with 

 the browns. 



The insects experimented upon were the following : — Orgyia 

 antiqua, Bombyx quercus (male and female), Orthosia macilenta(?) , 

 Mamestra oleracea, Cidaria suffumata, Coremia ferrugata, 

 C. munitata, and the chocolate (a) blotches and (b) lines on (a) 

 Bumia cratcegata and (6) Phalera bucephala. 



On the average twelve or thirteen reagents were used to test 

 each of these species ; and, in spite of their heterogeneity, they 

 agree admirably in being a most thoroughly unsatisfactory assem- 

 blage. There is nothing really definite to report of any of them, 

 except that in nearly every case the effect was nil. 



The most especially impervious were P. bucephala, B. quercus, 

 and C. suffumata. In one or two instances 0. antiqua faded 

 somewhat, and ammonia left it " darker and duller."' B. cratce- 

 gata faded a good deal, too, under the influence of the alkalis. 

 0. macilenta was changed to lighter and yellower, and M. oleracea 

 to a duller brown than the normal. 



Metallic spots and markings. — I had looked forward with very 

 great interest to experimenting on these colours (sic), but they 

 have proved wofully disappointing. Unfortunately I had only 

 two or three metallic marked specimens on which to experiment, 

 and it would be somewhat premature to conclude that all would 

 behave similarly ; but at any rate there is complete unanimity in 

 the few results that I have, and I shall hope for an opportunity 

 of supplementing these later. 



The species experimented on were Argynnis paphia, Plusia 

 gamma, Euplexia lucipara, and Dione passiflorae. 



A. paphia. This was tested by twenty-four reagents, and 

 the silver was left unaffected in each case, with a doubtful excep- 

 tion as regards nitric acid, which perhaps removed a little. 



D. passi florae.* Tested by the chosen seven reagents (see 



* A Floridan species of the Nymphalince, with magnificent blots of silver on 

 under surface of hind wings. This was one of a large number of specimens for 

 which I am indebted to the kindness of Mr. Geo. C. Griffiths, of Bristol. I am 

 .1 J " heavily indebted to Dr. Crowfoot, of Beccles, for similar generosity ; and gladly 

 l.ij e i lii opportunity of acknowledging the kindness of these gentlemen, as well as 



