= AAO 
Il. — Larve transferred from one to another temperature. 









NUMBER OF TEMPERATURES. SA ES 
emerging 
YEARS, UE in 
lots. | individuals. Early life. Later life. mors 
1909-10 . . 4 84 54°F.(129-13° C.)|60° F.(150-160C.)[14 = 1/6 
» 5 83 60° F.(15%160C.)|540 F.(120-139C.)] 1 =about!/so 
Total 1909-10. 9 167 _ — I5 
1910 Jr 6 DES 54° F.(120-130C.)|650 F.(18°-19°C.)|55 —nearly'!, 
» 4 34 65° F.(180-19°C 1549 F. (120-139 C.) 7 — about !/; 
Total 1910 . | 10 147 — 62 
By « short pupal period » is meant that which I consider repre- 
sented, in those experimented on by me, the period proper to the 
summer phase, i. e. 16 to about 4o days according to the temper- 
ature, the average of the 81 individuals being 23 days, the aver- 
age of the rest, 299 in number, was over 150 days, and not more 
than about 20 of these were under 70 days. Many of those of 1910 
are still (25 Sep.) in pupa.] 
Conclusions. 
I will now state certain conclusions to which my experiments 
have led me as to factors in seasonal dimorphism in climates 
where the main difference between the seasons is that of tem- 
perature. 
1. The life-habit — the long or short pupal period — constitutes 
the broad distinction between the winter and the summer phase. 
It is in the Selenias — and doubtless many other ZZeterocera — 
