Experiments in Rhythmetic Periodicity 171 
wings. By this time I was convinced that these happenings 
were to be accepted as action and not accident. 
Of course the dim light was some distance away and the 
bright light flush with the side of the box. Now the questions 
come to mind, whether the insects were far-sighted or near- 
sighted, and what difference would their vision make in their 
reactions. Unfortunately, no experiments could be made at that 
time to learn their response to a bright light at a distance. 
These laboratory experiments on the reactions to light bring 
us again to the puzzling question which probably will never be 
answered. In the open these males fly past street lamps, house 
lights and numberless automobile lights in order to reach my 
laboratory to meet the females there. Then when in that lab- 
oratory, they are so influenced by light rays that they leave the 
female nearby and passionately beat their wings on the win- 
dow toward the light until they die of exhaustion. 
Of course this experiment shows also the futility of trying to 
account for this behavior by phototropism. If the reactions 
were actually phototropic, then all of one lot should react, or 
not react, but all in the same way while under the same in- 
fluence. Loeb in citing his instances for animals of various 
orders says they did or did not react thus and so. He does not 
take into account exceptions, individuals that did not go with 
the crowd, and we assume that none existed. But here in this 
work we do find exceptions, and these exceptions should not be 
overlooked. A chain is as strong as its weakest link, and the 
theory is weakened just in proportion to the number of ex- 
ceptions. 
Exp. 16. May 21. The purpose of this experiment was to 
test on a larger scale the reactions of cecropia males to light 
of weak as well as strong intensity. Seventy-eight males came 
in at dawn that day; these were all placed in the large glass 
box and kept tightly covered with blankets. 
At 3:15 p. m., the cover was lifted at one end. The light 
at that time was the ordinary light of a room with two east 
windows. Almost immediately some of the moths began to vi- 
brate their wings, and in five minutes about three-fourths of 
them registered some response. Some waved the Wings, others 
fluttered to the light end, and many crowded and beat ease 
Selves against the glass in great commotion. The vibration o 
