THE PTERIDOPHYTA : FILICALES, THE FERNS 



499 



cell. This may again divide several times so that the axis of the neck is 

 occupied by a file of cells with thin walls. The lower portion of the central 

 cell divides into a small upper portion, the ventral canal cell, and a much 

 larger portion which becomes the oosphere (Fig. 489). 



Jacket I 



cells ' 



Oosphere ^y ^^ 



Ventral 

 canal cell 



Neck canal 

 cells 



Neck 



B 



Fig. 48g.—Dryopteris filix-mas. A, Archegonia developing on the lower surface of the 

 prothallus behind the apical cell. B, Longitudinal section of mature archegonium before 

 opening of the neck. Conipare with Fig. 488, E. 



(A, By courtesy of the General Biological Supply House Inc., Chicago, Illinois.) 





% ? 





9 









^*' ■■■' 





Antherozoid 

 nucleus 



.-* Oosphere 

 nucleus 



Fig. 490. — Dryopten's sp. Nucleus of oosphere after fertiliza- 

 tion showing enclosed antherozoid nucleus. {After 

 Yamanouchi). 



