LYCOPODIAU-.S 





archegonium consists of a neck (;/) composed of two tiers of four cells 

 each : a canal-cell (c.c), ventral-canal- Cell {v.c.c), and the ovum [ov.) ; 

 all of which were derived by segmentation from a sin uperficial 

 cell of the prothallus (V.). When mature the neck is open, the 

 canal-cell and vcntral-canal-cell have disappeared, and the ovum, 

 which is now a rounded primordial cell, is open to access of the 

 spermatozoids. As both types of spore germinate together, fertilisa- 

 tion is readily carried out. If the germination of the two types of spore 

 is compared with that seen in Ferns, it appears that while in both the 



B 



A 



Fig. 413. 



Embryos of Selaginella denliculata, after Bruchmann. el — suspensor. a/ = root. 

 /=foot. W = basal wall. A=hypocotyl. s = ape.\. k, ft 1 = rotyledons. / = ligulc. 

 (After Bruchmann.) 



vegetative region of the prothallus is reduced, and does not take part 

 in active nutrition, the antheridium and the archegonium are in 

 essential correspondence with the like parts in Ferns. 



After fertilisation the zygote secretes a protective wall, and elongat- 

 ing in the axis of the archegonium, segments repeatedly (Fig. 412, 

 VI.-VIII.)toform a filamentous suspensor (s) which thrusts the embryo 

 down deep into the prothallus (IV.). The distal cell soon enlarge 

 and divides. It gives rise centrally to the apex of the stem [st) t with 

 cotyledons right and left (c, c). Meanwhile unequal growth turns it 

 to one side, and the convex side enlarges into the suctorial ot ' 

 (IX. /). Lastly, the first root (wt t Fig. 4' 5, A t B) is initiated by 

 periclinal divisions close to the attachment of the suspensor, and on 

 the same side of the embryo. All the parts of the young embryo have 

 thus been produced, while the apex of the axis occupies the distal 

 position from the very first in the curved embryo. As the axis and 

 root grow they protrude from the ruptured spore, the root turning 

 downwards, and the elongating hypocotyl turning upwards (Fig. 41 J, 



