144 O'NEAL: EMBRYO SAC DEVELOPMENT IN OENOTHERA 
7. Fertilization occurs in about thirty-six hours after poll- 
ination and is probably single. 
In conclusion, the writer is pleased to take the opportunity 
of acknowledging his debt of gratitude to Professor D. M. 
Mottier, of Indiana University, who assigned this problem 
and who, by friendly advice and encouragement, has aided much 
in bringing this paper to its present stage of completion. 
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OuIO WESLEYAN UNIVERSITY 
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