16 Trans. Acad. Sci. of St. Louis. 
SAMTA CECROPIA. 
In the paper already referred to we paid most atten- 
tion to the Cecropia moth, chiefly because this species 
could be procured in greatest numbers. In this paper 
we deal with five additional lots of this material under 
normal conditions, and three lots (controls) which will 
be taken up in detail later. The five lots are as follows: 
River des Péres (St. Louis) normal cocoons. 
River des Péres fiuffy cocoons. ; 
South St. Louis cocoons. 
New York cocoons. 
Fall River cocoons. 
Before going into the details of this work, it may be 
well to give a brief resumé of the previous experiments. 
The River des Péres Cecropia population emerging 
in the spring of 1910 split up into two distinct lots; all 
of the moths which emerged early, April 13 to May 14, 
lived long lives (the mean for this portion of the popula- 
tion was 16.65 days), while all of those which emerged 
late in the season, May 14 to June 17, lived short lives 
(the mean for this group being 10.14 days). In 1911 this 
splitting up did not occur, but the three lots of material 
known as the St. Louis Cecropias 1911, the New York 
Cecropias 1911, and the Incubator Cecropias 1911, gave 
a mean duration of life of 7.71 days, 8.06 and 8.00 days 
respectively. This gave a clue to the following hypo- 
thetical explanation. The 1910 material began to 
emerge in April, a month earlier than usual. This ab- 
normally early emergence was perhaps due to the excep- 
tionally warm month of March, and when the unusually 
cold weather followed in April the animals lived notice- 
ably longer than usual. It was thought that the cold 
was directly responsible for this long life since they were 
numb and remained quite inactive, and hence expended 
little or none of their reserve ener , and that those 
moths which emerged later found the weather warm and 
