PLATE 27 



A. — Longitudinal section of the 4-celled embryo sac. X 800. 



B. — Longitudinal section of an 8-celled embryo sac at the time the polar nuclei 

 have started to migrate. X 800. 



C. — Longitudinal section of an 8-celled embryo sac after the polar nuclei have 

 migrated. X 800. 



