18 



females. One female was taken on May 2nd, 1893, an ^ all the 

 larvae from her ova pupated by June 7th, but none emerged till the 

 spring of 1894. The other female deposited ova on May 8th, and 

 one, a female almost intermediate in form between the spring and 

 summer forms, emerged on June 24th, but all the others remained 

 in the pupa? till the spring of 1894. 



One suspects that these were kept in some particularly cold situa- 

 tion. An exceptionally cold summer, such as that we have lately 

 experienced, causes a much increased proportion to lie over the 

 winter as pupae. 



I take exception to the terms spring and summer Broods of the 

 Whites, as tending to confuse distinct points. 



In England, breeding from butterflies of the spring emergence, we 

 get a number of pupae, some of which produce imagines in the 

 summer, while the rest lie over till the following spring (1). From 

 the insects of the summer emergence we get pupae, some of which 

 may produce imagines in the autumn, while the remainder lie over 

 till the spring (2). If the progeny of the autumn insects are able to 

 pupate, we shall then have another set of pupae lying over till the 

 spring (3). At any rate, we have two, if not three, distinct sets of 

 pupae producing imagines in the spring. 



Summer Spring (1). 



Autumn Spring (2) 



Spring (3) 



I do not know whether even in a very favourable year any of the 

 progeny would reach the pupa stage, but if so these would lie over 

 till the spring. 



It is, therefore, better to speak of the butterflies of the spring and 

 summer emergences. 



In Leucophasia sinapis we find that the pupae which are obtained 

 when breeding from ova deposited by butterflies of the spring 

 emergence are of two distinct forms, one with and one withoutp nk 

 lateral lines. Those without the pink lines will emerge in the summer 

 of the same year, and those with the lines will lie as pupae till the 

 spring of the following year. It appears, therefore, that the period of 

 emergence is determined before the formation of the pupae. I should 

 be glad to hear if others have had any experience of pupae with pink 

 lines emerging during the summer, or of any without the lines lying 

 over the winter. Similarly, in P. napi Mr. Montgomery found differ- 

 ences in the pupae, and was able to separate those which were intending 

 to emerge the same year from those intending to lie over the winter. 



