PLATE 31 



A. — Vegetative and sperm nuclei of the pollen grain: vn, vegetative nucleus; sn, 

 sperm nuclei. X 1,100. 



B. — Longitudinal section of the lower portion of the embryo sac at the time of fer- 

 tilization, reconstructed from two sections: pn, polar nuclei fusing; sn^, sperm nucleus 

 fusing with a polar nucleus; e, egg; sn, sperm nucleus in the egg; pt, pollen tube; 

 syn, synergid; v, vacuole. X 1,100. 



