LONGEVITY IN SATURNIID MOTHS 203 
will be known only after much work has been done upon the 
relation of longevity to the function of reproduction in a vast 
variety of species. 
Our work leads us to believe that there are still factors unknown 
which influence the duration of life. One of these, the influence 
of climatic conditions upon the length of life in the Cecropia 
moth, we have been fortunate to discover. If it were only adverse 
conditions curtailing life, no great significance could be attached 
to it, but when favorable, though abnormal, conditions were dis- 
covered and supplied, life and activity continued far beyond what 
was thought to be possible. This has hitherto not been considered 
in any of the theories, and the experimental work here recorded 
shows this factor to be of importance. There are no doubt many 
other influences awaiting discovery, which will have to be con- 
sidered before we dare philosophize upon the subject. 
It would be well to suggest some of the phenomena yet to be 
investigated upon a wide variety of material before a theory can 
be firmly established to account for the duration of life. 
1. The difference in the duration of life of the sexes. 
2. The duration of life of mated and unmated individuals of 
both sexes. 
3. The proportionate numbers of the sexes. 
4. The maturing of one sex before the other. 
5. Monogamy or polygamy. 
6. The relation of longevity of the female to the welfare of 
the young. In some forms where the parents do not care for 
the young, is the duration of life sufficient for bringing forth all 
the young (e.g., complete oviposition or seed-bearing), and in 
those which care for the offspring, is the length of life adequate 
for the necessary care of the young (e.g., food and flying in birds)? 
7. Number of potential ova that the organism may possess 
when overtaken by death. 
8. Does old age cause the inability of the individual to bring 
forth the young, although sexually capable? (e.g.; lapse of time 
after incomplete oviposition in the Cecropia). 
9. What proportion of the eggs deposited by a mated female 
are fertile? 
