OF FERNS FROM THEIR SPORES. 139 



Fig. 75. Section passing through the embryo-sac of an archegonium in which cell-development has com- 

 menced in the embryonal vesicle. 



Figs. 76 & 77- Sections showing subsequent stages. 



Figs. 78 & 79- Other sections in more advanced stages ; in fig. 79 the papilla of the archegonium is cut 

 through. 



Fig. 80. View of a young plant developed from the embryonal vesicle. The cellular mass, a, probably the 

 undeveloped radicle, lies loosely in the cavity of the decaying prothallium, d, d, on which the 

 archegonium (g) is seen ; b is the first leaf rising towards the notch of the prothallium ; c, the 

 first adventitious rootlet which has broken through at the base h; e is the second leaflet ; f, the 

 second adventitious rootlet visible in the interior. 



Fig. 81. A young plant making its third leaf; the prothallium has here quite decayed off. 



Fig. 82. Another young plant making its fourth leaf; a, b and c being the first, second and third. 



Fig. 83. A vertical section through the stem of this, removing about one-third of it in front, and showing 

 the nascent vascular system, and the relative positions of the stalks of the leaves a, b and c of 

 the last figure and of the nascent fourth leaf, d; between them are seen the brown cellular 

 ramenta. 



