Experiments in Rhythmetic Periodicity 191 
males 114 days old, 13 females 14 day old, 28 females 11% days 
old, 20 females 2 days old, and 20 females 5 days old. The 
moths of each lot were given a distinguishing mark for their 
identification. The object of this experiment was to see at what 
age the females were more likely to be influenced by the light of 
the uncovered window. The males were retained in the room 
to serve as a check. At 8 a. m. next morning, all of the males 
were at the window, and the following females: 
Number’ Percent 
Age, Number attracted attracted 
days. used. tolight. to light. 
% 13 0 0 
1% 28 18 64 
2 20 16 80 
5 20 17 85 
This shows most remarkably that age is a factor in the activity 
of the females; the figures in the per cents column speak more 
distinctly than words. 
At 9 a. m. the moths were replaced in their respective corners ; 
they were all, of course, a half-day old in this test. Up to 
noon, 3 males (2 of which had made two flights and 1 had made 
one flight previously) moved to the window; these were replaced 
and the experiment left alone until evening. At 9 o’clock, the 
census revealed that all of the males were again at the window, 
fluttering excitedly about the pane. Of the 81 heavily laden 
females, 62 had left the wall in their respective corners and were 
making their way slowly eastward, vibrating the wings intensely 
as they crept, as though being slowly but irresistibly lured or 
even dragged across the floor toward the light. Only 3 had 
actually reached the goal, and were climbing to the frame. The 
females were of all ages as follows: 
Number Per cent 
Age, Number attracted attracted 
days. used. tolight. to light. 
1 2 54 
2 28 24 85 
244 20 17 85 
514 20 14 70 
