124 Trans. Acad. Sct. of St. Louts 
ated 14 mile south. This lot consisted of 15 moths 114 days old 
and 7 which were 21% days old. None of the older moths re- 
turned, but 4 of the 114 day old ones came back, and all the 
same night, at 12:30, 1:23, 1:41 and 3:40. Here the proportion, 
18 per cent, would indicate that.this direction held some condi- 
tion imperceptible to us, which was more favorable to their re- 
turn than the north or east, but less favorable than the west. 
Of course my secret suspicions were that a current of air moved 
gently toward the west or sometimes south. 
Exp. 13. June 16. The foregoing experiments indicate that 
for some reason which I do not know the west is more favorable 
to the homecoming than any other direction. It seemed worth 
while to make one more attempt to solve this question. So at 
1:55 a. m. of the night of June 15-16, I took stock of my male 
eynthias, and threw all of my available material into one more 
test. There were in all 32 individuals, 14 of which had just 
come in from tests, and 18 which had emerged within the last 
24 hours. These were divided into two lots of 16 each and liber- 
ated in opposite directions, east and west, but at no great dis- 
tanee from the females. One lot, consisting of 7 young moths 
and 9 that had just come in from distant flights, was liberated 
50 feet east of the house. Since the indication was that the 
west was more favorable to their return, I handicapped those 
taken west by giving that lot a preponderance of young males, 
and I gave those liberated at the east point an advantage by 
assigning to their lot a greater proportion of experienced fliers. 
Of the 16 liberated 50 feet east, only one came back that night 
(after one hour and a quarter), and another came in the fol- 
lowing night at 10:55. 
Exp. 14. June 16. Conditions same as above. The remain- 
ing 16 moths, consisting of 5 experienced fliers and 11 newly 
emerged males, were liberated 50 feet west of the house. Of 
these, 6 returned the same night and 4 the following night. It 
is interesting to note that, although their normal period of 
activity was broken in upon by our interference at 11:55 p. ™, 
six of them extended their period of flight until from two to 
four o’clock, while those which laid over until the next night 
all performed at the hour of their own choosing, 10:55 to 12 
p.m. May it be that these four merely considered that aecord- — 
ing to ‘‘union”’ rules it was already quitting time when they 
