The Nuptial Flight 119 
aided in their later returns, I shall not presume to say at this 
point. I should like to think that these creatures profit by 
experience, but in a purely speculative way it seems more 
logical to attribute this superior ability to the natural 
(sensory) endowment of certain individuals. In their natural 
wild life, generation after generation, these moths have no pos- 
sible use for the ability to remember the trysting-place with 
their beloved and return to it, but it is hard to conceive of 
anything more vital in the perpetuation of the species than a 
fine native sensitiveness whereby the male can once locate his 
distant and unseen mate. The more specialized this sensitive- 
hess, the greater chance the individual has of leaving like 
progeny, for certainly the male that is lacking or deficient in 
this native faculty is in no danger of perpetuating his stupidity. 
Basing my judgment upon the action of the great majority 
of these moths observed, I feel convinced that the medium of 
attraction between the sexes is odor, or something so closely 
akin to it that we need not seek another name for it; that the 
males follow this odor trail on the wind to the site of the fe- 
male, and that they cannot orient themselves toward the female 
until they come by chance into a current of air carrying her 
emanations. 
When we tabulate the ratio of returns to the distance which 
the males had to travel, we get the following results: 
Experiment Number _ Distance Number _— Percent 
No. Liberated Miles Returned Returned 
= 19 1/200 9 ee 
_ Se ees 1/100 11 = 
2, 8, 4, 11, 30... 40 1/8 16 = 
eee 0 1/3 7 = 
5, 14, 15, 16, 18, 
ee eS eee _ 917 1/2 67 A 
13, 17, 31, 32, 37 ie a4 23 = 
Se 11/6 0 0 
ae Ps 11/2 1 
ee 13/4 7 ie 
Rs igs 2 3 : 
= 140 3 16 = 
