PAPERS ON BIOLOGY AND AGRICULTURE 141 



cocoons were parasitized, and thirty per cent dead through 

 fungus disease. 



2nd — In both moths, the lightweight cocoons produce 

 males ; the heavy cocoons, females. Thus, out of the thirty 

 heaviest Cecropia cocoons, no males were produced ; and 

 out of the heaviest fifty, only five males. Out of the lightest 

 thirty, nine females came; out of the lightest fifty, seven- 

 teen. The proportion of males to females in the whole lot 

 was fifteen males to thirteen females. 



3rd — Males were much more subject to death through 

 fungus disease than females. 



4th — The cocoons were kept indoors in a warm base- 

 ment from the time of collection in November until they 

 hatched in the following spring. The time of the appear- 

 ance of the moth from the cocoon was about a month earlier 

 than control cocoons left outdoors during the winter. 



5th — The correlation bet^veen the weight of the pupa and 

 the weight of the silk in both Cecropia and Polyphemus 

 cocoons is low, and that between the weight of the pupa and 

 the weight of the moth is still lower. 



6th — There is a fairly close correlation between the 

 weight of the pupa and its loss of weight in emerging from 

 the cocoon. 



7th — Males lose a much larger proportion of their pupa 

 weight in transforming into moths than do females. 



8th — Cecropia is much more variable in the weight of 

 both pupa and silk than is Polyphemus. 



9th — Cecropia is much more subject to parasitization 

 than is polj'phemus, at least in those stages examined. It 

 may be that the Polj-phemus larvae are killed by parasites 

 before the cocoon is made. 



