196 Trans. Acad. Sci. of St. Lous 
stronger response to light, because odor is ruled out; if the eyes 
are blackened so that light is excluded, one ought to get better 
response to odor stimuli. The lack of material at the end of 
the season prevented me from putting this point to test. This 
could be done by blowing a stream of odor from one sex upon 
the other and when the insect is thus aroused, see whether it 
follows the odor trail to the source or flies away to the light 
instead. 
In the blind tests, without the artificial currents of air, the 
response to the light was surprisingly high, but this may have 
been due to faulty technique. When the moths were examined 
later, a few tiny cracks were perceptible in the hard paint on 
the eyes; this may have been sufficient to admit enough light to 
guide them in their flight. 
MeIndoo insists that the olfactory organs are not situated 
in the antennae. 
If we remove the antennae of males or females, and get better 
reactions to light because they can perceive no odors, and if 
then we blind others and get better olfactory responses because 
they are not distracted by light, would not that show the seat of 
the olfactory sense ? 
Experiments on Cecropia and Polyphemus in Reaction to Light. 
It seemed to me that if phototropism were the cause of the 
reaction of these moths to the light, we should find all of the 
moths of one age responding at the same time, and if after they 
had flown to the lighted area they were immediately replaced 
they would again react in unison, so that when the experiment 
ended, all would have made the same number of trips to the 
light. With this in mind, planned experiments with the fol- 
lowing technique. 
A room, 15 by 10 feet, had a small, uncovered window at one 
end; the opposite end was dimly lighted, closely resembling 
twilight. At this dark end, a blanket was tacked to the wall, to 
give a comfortable foothold to the moths. The insects were 
placed on this at the beginning of the experiment, and as soon 
