188 PHIL RAU AND NELLIE RAU 
(about the mean temperature for the period in 1910 when the 
moths emerged). Up to the 10th of January, nothing had 
emerged. At this time a living-room was obtained with a fairly 
even temperature. Up to the middle of February no results 
were obtained. It then became necessary to remove the entire 
lot to the basement, the temperature of which, while not recorded, 
was moderately uniform and distinctly higher than that out-of- 
doors. They were sprinkled with water at intervals of a few 
days. These details would not be worth recording but for 
the fact that it was expected that under these conditions the 
insects would probably emerge somewhat earlier than the normal 
time. On the contrary however, the 162 insects which emerged 
(72 males, 90 females), left the cocoon between June 5 and July 
9, the latest period yet met with in Cecropia work. 
This lot was gathered early and placed in the incubator very 
soon after pupation, while probably some of the cocoons still 
contained larvae. It seems that the constant even temperature 
conditions at this stage made the animals lethargic and indiffer- 
ent to the normal development, when only a year before an unu- 
sually warm March had probably caused many to emerge sooner. 
The warm March of 1910 caused an earlier emergence, but 
warmth was furnished to the insects at a period of their develop- 
ment when they were susceptible to its accelerating influences, 
but when it was given them at an early stage of their pupal devel- 
opment, counter results were obtained. 
Can it be that they spun their cocoons in preparation for 
the cold of winter, but just about the time or even before they 
had left the larval stage their summer (i.e., high temperature) 
was resumed so they lacked the stimulus (cold) to start them 
promptly in their pupal development? 
If we had reason to believe that the first animals to pupate are 
the last to emerge, this would easily explain in part the lateness 
of these in emerging, for they were all gathered very early in the 
pupating season, while many caterpillars were yet to be seen. 
We cannot believe, however, that this can be a full explanation 
for the phenomenon, for the lateness of these toc far exceeds 
that of any others observed from the same region, either in cap- 
tivity or free. 
