42 Trans. Acad. Sci. of St. Louis. 
oviposit whether or not mating has taken place, and 
their life is of no longer duration than that of their fer- 
tilized sisters. In the three cases observed egg laying 
occurred within 3 or 4 days after hatching. Perhaps Weis- 
mann’s emperor moth could live for days or weeks in a 
torpid condition, awaiting impregnation, on the accu- 
mulated reserve nutriment. But in the Cecropias we 
found both males and females so active that all efforts 
were made to mate them early in life. This was done to 
avoid damaging their wings and also to avoid an exces- 
sive expenditure of vitality, which probably would have 
shortened their lives. 
In his essay on the Duration of Life’ Weismann points 
to the case of Aglia tau, in which the duration of male 
and female life is unequal. He says: ‘‘The males cer- 
tainly live for a period of from eight to fourteen days, 
while the female moth seldom lives for more than three 
or four days.’’ This, he seems to think, is an adapta- 
tion for the good of the species, for he says the males 
‘‘fly swiftly in the forests, seeking for the less abundant 
females. ’’ 
Weismann evidently means that the males fly swiftly 
through the forests after impregnating the females, al- 
though he may possibly mean that they do so before mat- 
ing. If the former is true, we must assume that the spe- 
cies is polygamous, and, if the latter, that it is monaga- 
mous. 
Both Agha tau and Samia cecropia belong to the family 
Saturniidae (Claus). The greater duration of life of the 
male, that we found among the Cecropia moth, is some- 
what analogous to that of Aglia tau, but how this dif- 
ference can prove of benefit, at least in the Cecropias, I 
have no way of telling. Were the species polygamous, 
perhaps the longer life of the male would be of value 
to the race, were it not for the fact that the life of the 
male, after leaving the female, is one of inactivity and 
5 Essays on Heredity. English translation. 18. 1891. (2d Ed.) 
