74 Trans. Acad. Sci. of St. Louis. 
5. In the Cecropias we find the mean for the St. 
Louis population to vary from year to year between the 
extremes of 7.71. and 16.65 days. 
6. By keeping Cecropias and Polyphemus in low tem- 
peratures the length of life is greatly prolonged. 
7. The mean number of eggs carried by the five lots 
of Polyphemus varies from 198 to 293. In seven lots 
of Cecropias the mean varies from 195 to 344. The 
Prometheas show little difference in egg production 
despite the remote regions (Massachusetts and Mis- 
souri) from which they came. 
8. In the Cynthias, Cecropias, Lunas and Prometheas 
the mated females oviposited more nearly completely 
than the unmated females. 
9. <A total of 3569 Saturniid cocoons gave 1879 males 
and 1690 females, or 111 males to 100 females. 
10. The males emerged from 1 to 5 days ahead of 
the females in practically all of the material here con- 
sidered. 
11. We find no relation between the length of time 
spent in mating and the fertility of the eggs. We have 
eut the normal length of time of up to 24 or even more 
hours, to 2 hours without diminishing the fertility of 
the eggs. There is no relation between the fertility of 
the eggs and the order of their deposition. 
12. The period of incubation of the eggs varies with 
the climatic conditions. 
GENERAL CONSIDERATIONS AND Concuustons. 
In the previous paper we have reviewed fully the 
theories which have been advanced in an attempt to ac- 
count for the duration of life. With material represent- 
ing, as this does, only one small corner of the organic 
world, we cannot hope to formulate generalizations 
which would be applicable to all organisms, while to pre- 
sume to build up entire theories upon the evidence in 
hand would be to repeat the error which has already 
