118 Trans. Acad. Sct. of St. Louis 
In considering the return of the moths when liberated in 
favorable or unfavorable winds, only the 106 which came in 
during the following dawn may really be accepted as reliable 
evidence, since we cannot know what factors, the shifting of 
winds, the interference of other mates, etc., are responsible for 
their wanderings. Even when only a few hours elapse between 
the time of liberation and the hour of return, there is abundant 
chance for the wind to change for a time, or to be deflected by 
the obstructions of the city. Out of 630 moths set free in 
favorable or partly favorable winds, or no wind, 98, or 16 per 
cent, returned at the following dawn; out of 78 liberated in a 
wind which was at the time of liberation unfavorable, 8, or 10 
per cent, returned. This method of studying the direction of 
flight of the moths and their method of orienting themselves in 
relation to the wind is not so fruitful of results as merely to 
watch keenly in the moonlight or dawn, and see from what di- 
rection they fly. At times the moths came too thick and fast 
for me to see their direction, but in the many cases where I was 
able to make this observation, the great majority of them 
arrived flying against the breeze. In the experiments with 
cynthias, as you will see later, we found data much more con- 
elusive in favor of their coming home against the wind; here 
we find that with the wind favorable for carrying the female 
odor to the point of liberation of the males, 38 per cent re- 
turned, and in an unfavorable wind only 8 per cent returned. 
This type of experimentation and deduction is the correct one 
for cynthia, for these moths fly early in the night; this is so 
soon after the time of liberation that there is little chance for 
the change of wind. Moreover, their attention is not diverted by 
wild females in the shrubbery. 
Thus the majority of them came galloping in facing the 
wind, from which we conclude the wind had carried them the 
message of the whereabouts or at least the direction of their 
mates. Some proved their ability to come in repeatedly, and 
some of these distinguished themselves either for speed or for 
overcoming difficulties. Whether this superior ability was due 
to finer native sensitiveness, which resulted in superior ability 
in this most vital quest, or whether their native endowment was 
augmented, after one or two experiences (which covered tenth 
or more of their natural lifetime), by associative memory whieh 
