PTERIDOPHYTES 



29 



outermost one of this row of cells, they are called primary neck cell, 

 central cell, and basal cell. The primary neck cell, by successive divi- 

 sions, develops a neck consisting of several tiers of cells (figs. 284- 

 286), with four cells in each tier. The central cell develops the axial 

 row as follows: the first transverse division results in the primary 

 neck canal cell (the outer one) 

 and the primary ventral cell 

 (the inner one, fig. 285). By 

 successive transverse divi- 

 sions, the primary neck canal 

 cell produces a variable 



Fig. 277. — Gameto- 

 phyte (g) of Lycopodhtm 

 annotinum (entirely tuber- 

 ous and subterranean), 

 bearing a young sporo- 

 phyte (s, I); the ground 

 line is shown. — After 

 Bruchmann. 



Figs. 278-282. — Antheridium of Lycopodium 

 davatum: 278, to the right a young antheridium 

 after the first division (periclinal) of the super- 

 ficial initial cell; to the left a much older 

 antheridium; 279, young antheridium after di- 

 vision of primary wall cell and primary sperma- 

 togenous cell; 280, further development of 

 spermatogenous tissue; 281, nearly mature an- 

 theridium, showing the wall (consisting of one 

 layer of cells) and the mass of spermatogenous 

 cells; 282, two sperms, showing the biciliate 

 character. — After Bruciiman W. 



number of neck canal cells (fig. 286) ; in some cases four to six, but 

 in other cases as many as thirteen have been observed. This ex- 

 traordinarily large number of neck canal cells is regarded as a low- 

 character, since a steady decrease in the number of neck canal cells 



