74 THE BUTTERFLIES OF THE BRITISH ISLES. 



by subjecting summer chrysalids to a temperature of about 

 no° Fahr. during three to five consecutive days, the chrysalids 

 being placed in this heat four times a day, and for a period of 

 one hour each time. Dr. Max Standfuss, who has made many 

 experiments with this and other butterflies, states that the 

 result of such treatment as that adverted to, and as regards this 

 species, has been the production of as many as seven of the 

 varieties among forty specimens. It would seem probable, then, 

 that the varieties occurring in the open are from chrysalids 

 that received a greater amount of heat than those that produce 

 the ordinary butterfly. 



It has been stated that the borders are ochreous, but this 

 only applies to the specimens seen in the summer or early 

 autumn. The butterflies hibernate, and when they leave their 

 winter retreats in the spring, the colour of the border is con- 

 siderably paler and often even white. For some time it was 

 considered that white borders were a peculiarity of the British 

 Camberwell Beauty and stamped it a genuine native. Probably 

 there are some who may still hold this opinion. An example 

 of each form is represented on Plate 43, the upper one was 

 taken in the spring, and the other in the autumn. Both belong 

 to Mr. J. A. Clark, to whom I am indebted for their loan. 



The egg is at first deep ochreous yellow, changing through 

 olive brown to red brown, and a day or two before the larva 

 hatches out becoming leaden grey. The ribs, which are eight 

 or nine in number, are most prominent below the top, and dis- 

 appear before the base is reached. The eggs are laid on twigs or 

 stems in small batches of 30 or 40 up to large ones of 150 to 250. 



The caterpillar has been described by Mr. Frohawk, who 

 gives a full account of the life-history of this species in the 

 Entomologist for 1902 and 1903. The following is an abridge- 

 ment of his description. 



The head is bilobed, having a deep notch on the crown, and 

 of a dull black colour, covered with black warts, each emitting 



