e) Cha 
9. Applied during the latter part of larval life only, a « spring » 
temperature promotes in S. bilunaria large size and long pupal 
period. 
10. Applied during pupal life, a high temperature tends to give 
the facies proper to the summer phase, a low temperature the 
facies proper to the winter phase; but the life-habit of the summer 
phase, under normal circumstances, usually carries with it the 
subjecting of the pupa to a high temperature, that of the winter 
phase to a low temperature. 
11. There is great individual variation in nature as to the periods 
during which individuals, even those belonging to one brood, may 
remain in the egg, larval and pupal stages. T'hus, in general June 
larva of A. levana belong to the summer phase, and August larva 
to the winter phase, some individuals, however, often going over 
the border line in each case; and these variations have a tendency 
to form into groups so as apparently to split a whole brood 
into two or more groups. I think the application of unusual changes 
of temperature increases the tendency to splitting. 
I well realise that seasonal dimorphism is a very large subject, 
and that mine are but small contributions to it, but I offer them in 
the hope that they may be of use to others able and willing to 
follow up the investigation with greater precision than has been 
within my reach. They may be regarded as building stones, out of 
which, aided by materials supplied from many other climates and 
by many other minds, a fairly complete and symmetrical fabric 
may hereafter arise. 
