202 Trans. Acad. Sci. of St. Louis 
each, as compared with 214 flights each for those of the first lot 
when the weather was ten degrees cooler. This indicates a 
marked increase in activity during the warmer days, but since 
the males which were under experimentation at the same time 
showed a slight decrease in activity at that time, the difference 
is probably due to something other than temperature. 
These, like the males, showed no tendency to move simultane- 
ously ; some flew promptly and often, and others waited as long 
as 48 hours before making a start or repeating a flight. 
An attempt was made to study the reaction to light of blind 
cecropias. This work was done simultaneously with Exps. A 
and C. The eyes of 17 males and 10 females (see Table 11) 
were painted with two coats of black stove enamel; this, it 
seemed to me, should have permanently ended their vision with- 
out causing them to suffer the shock of mutilation, but I have 
no guarantee that it actually did so. The males under these con- 
ditions averaged just one-half the number of flights accomplished 
by normal males, in the same place and time; out of the 17, Table 
F, only 4 failed to respond. This shows at least that some were 
materially affected by the change, although the surprising thing 
is that any of them found the light. Of the females, only 4 out of 
10 found their way to the light. This amount of efficiency may 
indicate the presence of some unknown sense whose very exist- 
ence we have not suspected, but I am more inclined to attribute it 
to faulty technique, such as cracks forming in the painted area. 
I should like very much to see these experiments repeated, if 
some method could be devised which would be more efficient than 
painting the eyes without causing a severe shock to the moths. If 
the rhythmic periodicity of these creatures is a thing inherently 
fixed within their beings as a physiological process instead of a 
psychological one, then we should see those deprived of light 
stimulus reacting at certain periods of the day. Even after 
making generous allowance for faulty technique, I see no indi- 
eation of this concerted reaction. 
The same work was carried on simultaneously with polyphe- 
mus males and females. They displayed much greater varia- 
tion in the number of trips to the light than did the cecropias. 
Among the males, some waited long and seemed satisfied with one 
trip; others kept coming to the light as fast as I could carry 
