208 



EMBRYOGENESIS IN PLANTS 



but pollination has already taken place. In the proembryo phase, 

 eight free nuclei are present in the base of the archegonium. The 

 several species of Podocarpus show differences in the arrangement of 



3-4 4-6 



o 



10-12 9-12 



3 





3 <n 



3 3 

 £ 'a 



7-9 



7-11 



— 23 



9-12 7-9 



5-9 



.S2 



'55 



c 



tr -o 



o ™ 



9—11 



8-10 



3-6 



'5 



11— 13 



e 

 a 



J2 



2-3 



^ 3 



7-10 



^ 



1—2 



2 .3 



Fig. 49. Podocarpaceae 



Comparison of young embryos, showing variations in the number of prosuspensor 

 cells (numerals above figures) and in the number of binucleate embryonic cells 

 (numerals below figures). Podocarpus includes the widest range of variation found 

 in any genus of Conifcrales. (All diagrams are approximately to same scale; after 



Buchholz.) 



the proembryo cells. In Phyllocladus, eight free nuclei are present at 

 the base of the narrow, saccate archegonium. Fig. 48f, g; after a 

 further division the sixteen nuclei become arranged in tiers like an 



