Experiments in Rhythmetic Periodicity 175 
gardless of whether the experiments are carried on morning, 
noon or night. 
Exp. 19. This test was made to test the reaction of the female 
cecropias to light. In the literature one finds little or no men- 
tion of the activities of females, excepting their mating or egg- 
laying. People are satisfied with the assumption that the female 
merely sits and awaits the arrival of the male; hence it is start- 
ling as it is interesting to find, experimentally, that she some- 
times plays an active part in the meeting of the sexes. 
Thirty-two females, all from one lot of cocoons and all three 
days old, were placed in the dark box at 8 a. m. After 614 
hours the cover was lifted at one end and the six which chanced 
to be near that end were gently placed in the dark corner. 
Within five minutes seven of them had come to the light end; 
for a time two fluttered about excitedly, more actively than one 
would expect of a heavily laden female, but they soon subsided. 
Fifty minutes more were allowed, but no more responded to 
this stimulus. Then the light was changed to the 40-watt lamp 
with a reflector on the back, pressed against the end of the box. 
Only two more responded to this dazzling illumination by mov- 
ing ten inches toward it; a half hour brought no further move- 
ments. Lastly, the entire cover was removed, admitting dif- 
fused light of the room from all sides, but not a moth stirred. 
After a half-hour’s rest I placed a cage containing seven two- 
day-old males in the box, at the end nearest the window, and 
fanned the air into circulation. Within ten minutes eight of 
the females had flown to this end of the box and three of them, 
heretofore sluggish or immovable, were clinging to the cage des- 
perately beating their wings against the wire mesh. After 
fifteen minutes eleven females were around the cage of males, 
some of them in wild excitement. 
These tests show, then, that some females at least (7 out of 
32 in this ease) mildly register the perception of light per se, 
but when the stimulant of sex odor plus movement of the air 
is added, a larger number (11 out of 32) show intense excite- 
ment and aggressive action. This experiment clearly shows, too, 
that not all of the females are similarly endowed for the percep- 
tion of light or odor waves. 
To conclude, then, with an answer to the query in our open- 
ing paragraph, we find that some females at least are endowed 
