96 Mr. Mevrifield's incidental observations 



point in the life of a pupa when it may be said that a 

 corner is turned, and that the last stage of development 

 has begun, a point that seems indicated in E. versicolora 

 by the pupa's forcing itself out of its cocoon, the pupje 

 that do not thus come up remaining over till another 

 year. It is, I believe, a common observation in collecting 

 that it takes several warm days in succession to bring 

 out the moths that emerge in spring, and that after 

 such a succession they often become rather suddenly 

 plentiful. A passing remark on the usefulness of the 

 forcing-box will not be out of place here ; with some 

 experience it should enable one who is breeding insects 

 to bring them out almost to the day [if in combination 

 with a sufficiently capacious ice-chest] at the time when 

 he may be able to attend to them ; without such appli- 

 ances the heredity experiments as to size would be 

 rendered much more difficult, as in warm weather a 

 considerable percentage of moths, if kei)t a few days, 

 though in the dark, flutter so as to damage their wing- 

 tips, and make it impossible to measure them. 



One general result of the experiments appears to be 

 that cold aj^plied in the earlier stages (there being strong 

 indications that the larval period is one) in the life of 

 the 3 species experimented on, 2 of these species being 

 double-brooded, and one single-brooded, has a tendency, 

 operating possibly by retardation, to produce or develop 

 a darker hue in the perfect insect : if so, it may perhaps 

 throw some light on the melanism so often remarked in 

 north-country examples of widely-distributed moths. 



In conclusion, I hope to be allowed to say that I feel 

 as strongly as any odc can that the record of my experi- 

 ments would have been more satisfactory to others, as 

 it certainly would have been to me, had it been deferred 

 until they could have been brought nearer completion. 

 But I trust the reason which decided me to ofier them 

 in this imperfect form may be thought a sufficient 

 excuse, the reason being that I hoped others might be 

 induced to follow them up in the various directions in 

 which they point, and that, as to such as I may be able 

 to prosecute, I may receive suggestions enabling me to 

 conduct them the better. I have a great many recorded 

 observations other than those I have made use of here, 

 and they are entirely at the service of any who are 

 interested in the subject ; they give, in a tabular form. 



