346 



MOSSES AND FERNS 



CHAP 



if the earlier ones are not fertilised, they may continue to form 

 indefinitely ; but no correspondence can be made out between 

 them and the initial cells, and while formed for the most part 

 in acropetal order, new ones may arise among the older ones. 



The mother cell of the 



B 



Fig. 175. — A, Young archegonium of O. cinnamo- 

 mea, with the neck canal cell divided by a cell 

 wall ; B, a nearly ripe archegonium of the same 

 species, X525. 



archegonium is scarcely dis- 



tinguishable from the 



neigh- 



living 



bouring cells, either in size 

 or contents, and cannot al- 

 ways be identified until after 

 the first transverse divisions. 

 The development is much as 

 in the other Ferns, but there 

 are some differences that may 

 be noted. The first trans- 

 verse division, as in these, 

 separates the cover cell from 

 the inner cell, and the latter 

 may divide into a basal and 

 central cell, but sometimes 

 this division is omitted, and 

 the basal cell is absent. The 

 cover cell divides by the usual 

 cross-walls into the four prim- 

 ary neck cells, which here all 

 develop alike, and the neck 

 remains straight. The com- 

 plete neck has about six tiers 

 of cells. The separation of 

 the neck and ventral canal 

 cells follows in the usual 

 manner, but occasionally the 

 former may be divided by a 

 transverse cell wall (Fig. 175, 

 A), although ordinarily the 

 division is confined to the 

 nucleus. The neck cells have 

 state are almost transparent, 

 glistening bodies, apparently 



small nuclei, and in the 

 with little chlorophyll. Small 

 of albuminous nature, are often present, and are especially con- 

 spicuous in material fixed with chromic acid. Kny and Luers- 



