Experiments in Rhythmetic Periodicity 189 
I missed this observation, so this night means but little. In the 
morning I once more placed them on the south wall, to see if 
they would respond to the light of the window during the day. 
This test, with identical surroundings and material, had pre- 
viously given negative results during daylight hours. This time, 
however, there was some reaction, which shows that the moths 
can as they grow older, or through place memory, create new 
periods of activity. Before noon six of the males, almost one- 
fourth of them, had flown to the lighted window. These moths, 
remember, were the identical ones which had declined to do this 
trick for us on previous days, under conditions which were, so 
far as we could see, identical. 
These six were replaced on the wall. At 8:30, I found them 
all fluttering about the room; 9 went to the window during my 
five-minute visit, but I could not remain with them. At 11 p. m., 
25 of the 28 males were on the window. The moon did not ap- 
pear until 9:15. 
N 
wt 
> 
& 
x Darkened Window. 
a 
Mm 
£ 
= Light Window 
(Shode 74 Open) 
¢ 
a 
Exp. 24. June 28, 9:55 p. m. This experiment was arranged 
as indicated in the diagram above. All of the moths were % 
day old, 28 males were placed in the northwest corner and 28 
females in the southwest corner of the room. One window on 
the east was darkened, and the other had the shade lifted four 
feet. The objects were to see: 
(a) If both sexes would go to the light; 
