1908] 



COW—EMBRYOGENY OF ARISAEMA 



41 



inner (functioning) cell is usually o. i"''^ in length, and its nucleus, by 

 successive divisions, gives rise to the usual eight nuclei of the embr}-o 

 sac (figs. 7-1 1). The oosphere, synergids, and antipodal cells are 

 organized as usual, and the polar nuclei fuse {f^g. 12). The fusion 

 endosDerm nucleus freauentlv contains two nucleoli {fig. 13). , 





- * 



-f. ^' 



J-t 





&r 



; - r ' ,-' f 





16 



<-' '"■> ■',. 



o 



S®3 



Fig. 14. Ovary at period of fertilization; e, embrj-o sac; p, placenta. X36.--- 

 Fig. 15. Oosptere and male nucleus. X920.-F1G. 16. Endosperm nucleus and 

 second male nucleus. X920.-F1G. 17. Diagonal section of ^"^^-0 sac near chaiaz^ 

 extremity, shou-ing endosperm and, probably, one antipodal dislodged by kmfe. X 9^ 

 -FIG. 17a. Endosperm nuclei enlarged. X2C50.-F1G. 18. Endosperm nuclei X^ 

 -Fig. 19. Longitudinal section of endosperm (6). surrounded by remams of rn^r 

 integument (.), and of nucellus (a), and containing embr>^o (.). and la^ ^^^'^Jf^ 

 X14-F1G. U. Two-ceUed embr.-o. Xp—FiG. ax. Three-celled embno. Xg-'- 



celled 



divisions are 



embryo sac has 



increased 

 lus h 



The lateral ceUs 



been srre 



intact. The 



and outer integuments have gro..-n until iher press against 



in the roof of the ovary (fig 



\ 



The stigma of .Irisaema consists of a 



IooscIt compacted 





ewhat mucilaginous papillae 



(fig, II). The poHen tube finds 



