354 



MOSSES AND FERNS 



CHAP. 



B 



The mother cell of the archegonium is scarcely distinguishable 

 from the neighbouring cells, either in size or contents, and can- 

 not always 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 

 primary neck cells, which 

 here all develop alike, and the 

 neck remains straight. The 

 complete 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. 

 197, A), although ordinarily 

 the division is confined to the 

 nucleus. The neck cells have 

 small nuclei, and in the liv- 

 ing state are almost trans- 

 parent, with little chloro- 

 phyll. Small glistening bod- 

 ies, apparently of albumin- 

 ous nature, are often present, 

 and are especially conspicu- 

 ous in material fixed with 

 chromic acid. Kny and 

 Luerssen both speak of the quantity of starch in the axial row 

 of cells in O. regalis, but in neither 0. cinnamomea nor O. Clay- 

 toniana was this noticeable. As the ^gg approaches maturity 

 the nucleus becomes large and distinct, and one or two nucleoli 



Fig. 197. — ^A, Young archegonium of O. 

 cinnamomea, with the neck canal cell 

 divided by a cell wall; B, a nearly ripe 

 archegonium of the same species, X525. 



