Experiments in Rhythmetic Periodicity 163 
early hours of morning. The next morning I was surprised 
to find that only six pairs had mated, and four of these pairs 
were at the edge of the group of cages nearest the open window. 
On another occasion when six young males were placed with 
32 healthy females in a large box with close-fitting glass lid 
so all circulation of air was excluded, only one pair mated. 
In contrast to these incidents, a cage on the roof blew over one 
morning, and in a very short while, before the females had had 
time to fly away, they had all mated with the native males 
which were coming in. These accidents seem to indicate that 
close proximity of the two sexes is not in itself sufficient to 
bring about the union unless a eireulation of air plays upon 
them and assists them in locating each other. 
Exp. 11. This too is only a group of observations pertinent 
to the subject in hand. That each of the five species of 
Saturniids has a specifie odor. no one will deny. The odor of 
any one species is perceptible to the human olfactory organs, 
but if a difference exists in the odor of the two sexes of each 
Species, it will take a very acute sense to distinguish between 
them. The following notes, meager as they are, will throw 
some light on the subject. 
On May 6, when I entered the laboratory, I immediately per- 
ceived a strong cecropia odor, although there were only fifteen 
moths of both sexes there, and five windows on the east and 
west walls were all open. This shows the heaviness of the 
odor and its staying qualities. From this time on it was no 
uncommon thing for the members of the family, when on the 
Street in front of the house, to catch a strong whiff of cecropia 
odor on the breeze. Moreover, on several occasions when they 
Were out riding, they would pass through a ‘“‘streak”’ . 
cecropia odor in the atmosphere; in these cases the odor seemed 
actually to form a distinct, clear-cut stream through the air, 
like the Gulf Stream through the Atlantic. My wife sniffed the 
limits of one such stream and found it, according to = 
olfactory sense, to be about fifteen feet wide, and distinet 
enough that she felt sure that she could have followed it ard 
against the breeze to its source if the traffic on Pennsylvania 
Avenue had not been so heavy at that point. Of course she 
had no way of knowing whether the moths were near or far. 
This characteristic form of dissemination of the odor is of im- 
