68 



' aberration,' nor do I refer to local forms, but only to 

 colouring, markings, etc., in a species when confined to one 

 locality. There has been much, and sometimes acrimonious 

 discussion, as to the causes of such variation, atmosphere, 

 soil, moisture, dryness, etc., especially food. Further, many 

 suggestions have been made as to methods of producing such 

 variations — viz., change of ordinary food, more or less light, 

 or no light at all, etc. After nearly fifty years experience, 

 the conclusion that I have come to is a very simple one — 

 namely, that we know nothing whatever on the subject, and 

 that we never shall. Allow me to illustrate my meaning. 

 The insects which I have drawn and coloured are some of 

 the more striking varieties selected from over two thousand 

 bred during the past two summers. They are accurately 

 (so far as has been in my power) drawn and coloured as to 

 size, shape, variation, markings, and difference in the right 

 and left sides of the same specimen. In addition, I had 

 at least a thousand which perished from various causes — 

 ichneumons, disease, etc. Now, every one of these larvae 

 were taken within a mile radius of my house ; all, without 

 exception, were found on one plant, the common Euonymus, 

 growing in the gardens round about. In captivity they were 

 fed on the same plant, with the addition of the common cur- 

 rant. All were bred in the same room, the same light, no 

 effort was made to produce varieties by food or any other 

 means. I will ask you now to examine the drawings, espe- 

 cially figures I, 2, 3, 6, 8, lo and ii. How and why were 

 they produced ? We don't know, and we never shall. 

 Several of these variations I have never seen the like of. 

 Of course I let the majority of the perfect insects go, but I 

 have kept some three hundred or four hundred, no two being 

 exactly alike. It is rather a curious fact that at least four- 

 fifths of the most striking varieties are females." 



The chief peculiarities of the figures above referred to are: — 



1. Basal half of fore- wing almost entirely black, 



2. The whole insect dusted with black scales. 



3. Almost devoid of markings, except a few black dots; 

 asymmetrical. 



6. Markings on basal portion of wings almost obliterated. 

 8. Small size, and comparative absence of black markings. 



10. Black markings forming longitudinal streaks. 



11. Finely dusted with yellowish-grey scales. 



The other figures represented various modifications of the 

 above extreme forms. 



Mr. Barrett thought that variation was but little affected 



