S THE ENTOMOLOGIST. 



reddened.* Although, however, thus far successful, I have found 

 it utterl}' impossible to effect a reddening of a large number of 

 other species, e.g., Actias luna, Charaxes athamas. T. pronuha, 

 C. hera lutescens, R. cratcegata, and various others. As I 

 have pointed out in my previous articles, the failure to redden 

 pronuba and hera was peculiarly disappointing, for reasons that I 

 have already explained. Now, after experimenting on very 

 many species with KCN, I found myself face to face with one 

 general result of perhaps some significance, viz., that all the 

 reddened species belong to the Rhopalocera ; in no case had the 

 reaction been obtained with any Heterocera examined. It seemed 

 to me especially striking that even in the Geometrse I got no 

 results, for one would expect the yellow of the small brimstone- 

 moth (R. cratcegata) to be very similar to that of rhamni or Colias 

 sp. ; and, moreover, it is also affected by acids and alkalis in a 

 similar way. However, the fact remains that, so far, this reaction 

 cannot be obtained with Heterocera. 



After further experimenting I was struck by another fact, viz., 

 that not only was the cyanide-reaction confined to the Rhopalocera, 

 but within yet narrower limits, viz., to the family of the Pieridse. 

 Although yellow or orange species from the families of Papilionidse 

 and Nymphalidse have been tested, these fail entirely to give the 

 reaction. On the other hand, species which are — superficially — 

 of such different yellows f as rhamni, edusa, hyale, and (the under 

 surface of) Catopsilia crocale, all yield this cyanide red. We must, 

 therefore, conclude for the present that the yellow pigments of 

 the Pieridse, in spite of their strong resemblance in other respects 

 to the pigments of other families, + have, nevertheless, a marked 

 peculiarity of constitution, which is evidenced by their ready 

 reaction with cyanide. 



II. — Behaviour of Chestnut species. 

 Having in view the strong similarities between yellow and 

 chestnut (vide my former articles), it seemed to me very desirable 

 to ascertain whether the cyanide-reaction could be obtained with 

 any chestnut species, many of which (chiefly species of Nymphalidse) 

 were accordingly tested. In no case was any reddening effected. 

 This reaction remains, therefore, confined to the yellow and 

 orange Pieridge.§ 



* The intense yellow with which the mass of cyanide was stained in 

 many experiments was very notable. In one case I noted a slight reddish 

 tinge on the cyanide. This is of interest in connection with the Lithium 

 results, to be considered further on. 



■f This meets the objection, which might be otherwise raised, that the 

 orange Nymphalidae and the yellow Papilionidae are superficially dissimilar 

 from Colias and Gonepteryx sp. 



I See my previous articles in ' Entomologist,' — YeUow and Bied passim. 



§ It would be exceedingly interesting to test any chestnut species of 

 Pierid^, if any such are known. 



