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 

 cut 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 Conclusions. 



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 



