Experiments in Rhythmetic Periodicity 193 
above. Eventually all of the travelers reached the window or 
sash. Unfortunately the actual numbers in each class were lost, 
but all groups were represented, while in each group were from 
1 to 4 which failed to respond. The experiment adequately 
demonstrated that in a room without males or the possible odor 
of them, the females react to the light just the same as if the 
males were there; hence the light per se is the stimulus. 
Exp. 27. July 1. This was to be the final experiment of the 
season, so I took all the cynthia moths that I had on hand and 
placed them on the south wall of the third-floor laboratory. The 
light was admitted at only one window. I merely wanted to see 
how the moths of various ages, sexes and conditions would re- 
spond to the lure of the light. The lot consisted of: 
Normal moths: 8 females 2 days old, 6 females of unknown 
age, 6 males 2 days old, 17 males 4 days old. 
Moths with right antenna off: 3 females, 4 days old, 6 females 
7 days old. 
Moths with left antenna off: 5 females 2 days old, 3 females 
4 days old. 
Moths with both antennae off: 10 females 2 days old, 4 females 
4 days old. 
Moths with half of each antenna off: 2 females 2 days old, 3 
females 4 days old, 5 females 7 days old. 
Moths with paint-covered eyes: 7 males ¥y day old, 13 males 2 
days old, 7 males 3 days old, 15 females of unknown age, 13 fe- 
males 3 days old. 
These 133 marked moths were placed on the wall at 4 30 p. m., 
in time for them to become composed before their evening hour 
of activity. 
By 6:45 p. m., 22 moths (10 males and 12 females) were on 
the window; 6 of these were normal and 16 were mutilated, and 
in the lot were 2 blind males only % day old, for ye 
was the first night in this world, and 2 other blind males 3 days 
old, which of course had experienced twilight previously. These 
22 which responded about two hours earlier than their usual 
period of activity constituted about 17 per cent of the total popu- 
lation under experimentation. This test shows also that the 
moths are able to make the flight under the handicaps men- 
tioned above. In the entire lot 72 per cent were handicapped, 
