1864.] 53 



constitute but a single species. Collections have been made, in which 

 the extremes are connected by every gradation of shade. But it is 

 probable that any number of individuals, collected from one locality, 

 at one particular time, will present a very limited range of variation. 

 In the earlier years of its appearance in this place, those taken, with 

 very few exceptions, were nearly immaculate ; none were found having 

 the black veined yellow posterior wings, which during the last few 

 years have been so plentiful. 



I had hoped to institute a series of experiments and observations, on 

 the variations which this species offers, with a view of determining as 

 far as practicable, the following points, some of which had been sug- 

 gested for my study, by correspondents : 



a. The range of variation existing in the brood of a single 9 ■ 



b. The modification of variation, from the union of % and 9 "' *h® same 



style of variation. 



c. Ditto of different styles of variation. 



d. Ditto of the extremes of variation. 



e. Variation as modified, by the food-plant. 



/. Ditto by the impeded development of the larva by cold. 



9. Ditto by the impeded development of the chrysalis. 



My attempts were as follows. I gave a % and $ which had emerged 

 from chrysalis the same day, the freedom of a large, well lighted apart- 

 ment, in which had been placed sugar and water for their food, and 

 thrifty potted plants of horse-radish, cabbage, &c., for the $ to deposit 

 her eggs upon. They were found dead after the lapse of a few 

 days ; no eggs had been placed on the plants, and they probably had 

 not mated. 



I took pairs in coitu, and treated them as above, with the same 

 result. 



I captured females while depositing their eggs, and furnished them 

 with plants as above, but no eggs were found upon them. 



I inclosed in boxes, ovipositing females, with distended bodies ; re- 

 sult as before. 



It will be seen from the above, that all my efforts to pair the species, 

 or induce it to deposit eggs under the slightest restraint, were in vain. 

 I trust that others who feel an interest in the subject of the variation 

 of our diurnals, may be induced to prosecute its study, experimentally, 

 and that some method may be found of overcoming the difficulties 



