164 THE ENTOMOLOGIST. 



my readers, I may remind them that, having expressed myself 

 very sceptically as to this extraordinary transformation (Entora. 

 xxiii. 129), I was advised by Mr. Cockerell to try again with a 

 ivarm, damp cyanide bottle (Entom. xxiii. 20). To this I replied 

 next month (Entom. xxiii. 234), stating that this hint had been 

 acted upon, but still without effect, and promising details in due 

 course. These details I will now briefly give. 



In a very damp cyanide bottle I placed two wings of C. edusa, 

 and also, for comparison, two of G. rhamni ; one wing of each 

 was placed on the cyanide, and one pinned to the cork. The 

 bottle was placed for ^^ hours on the ledge of a gas-stove 

 (burning 15 ft. per hour), and 1^ in. in front of the flame. But 

 directly I read Mr. Cockerell's remark about the warming being 

 necessary, it occurred to me as highly probable that the cyanide 

 had nothing to do with the matter, but that heat alone would be 

 equally efficacious. I therefore made a blank experiment by 

 placing in a similar bottle a wing each of edusa and rhamni 

 (pinned to the cork), this second bottle being placed side by side 

 with the cyanide bottle, and exposed for the same length of time, 

 and under precisely similar conditions. Now as to the results : 

 in the cyanide bottle, after twenty minutes, the edusa wing on the 

 cyanide was chiefly white ! and, after forty minutes, entirely so, 

 this being no other than the usual solvent effect of cyanide 

 solutions and most other reagents on this species. As to the 

 wing pinned on the cork, it became somewhat broivnish ; and, 

 on washing it after the expiration of the 2|- hours, all the pigment 

 was washed away, together with the adhering cyanide which had 

 splashed up, — an exceedingly natural result. G. rhamni was 

 affected in pretty much the same way. At present, then, I was as 

 far as ever from getting Mr. Edwards' red. As to the wings in 

 the empty bottle, they were absolutely unaffected ; so that clearly 

 mere heat has nothing to do with the matter. But still I did not 

 rest here; there seemed a possible objection that might be made, 

 viz., that the heat of the gas-stove was too great, and a gentle 

 but prolonged warmth was necessary. So I placed fresh wings of 

 edusa and rhamni in the cyanide bottle, both on the cyanide and 

 pinned to the cork, and kept this bottle in a water-oven, where 

 for eight or nine hours daily it was exposed to a temperature of 

 100° (=212° F.). After eight days of this treatment the wings 

 on the cork were absolutely unaffected, while the edusa wing on 

 the cyanide was turned brownish as before. I therefore put the 

 matter aside as hopeless. (I might add that an empty bottle 

 containing similar wings, both pinned to the cork and resting on 

 the bottom, was similarly treated, and, of course, with wholly 

 negative results.) 



Addendum, December 5th. — The above was written on Nov. 

 4th, since when, however, I have — at last — succeeded in entirely 

 clearing up the discrepancy between Mr. Edwards' results and my 



