194 MOSSES AND FEIGNS chap. 



The cover cell, instead of dividing by quadrant walls, has a 

 regular series of segments cut off from it, and acts as an apical 

 cell. These segments are cut off parallel both to its lateral 

 faces and base, and thus form four rows of segments, the three 

 derived from the lateral forces forming the outer neck cells, and 

 the row of segments cut off from the base constituting the 

 axial row of neck canal cells. Each row of lateral segments is 

 divided by vertical walls, and forms six rows, which later divide 

 by transverse walls as well, so that the number of cells in each 

 row exceeds the original number of segments. This is not the 

 case with the canal cells, which, so far as could be determined, 

 do not divide after they are first formed. The wall of the 

 venter owes its origin entirely to the three peripheral cells 

 formed by the other primary walls in the archegonium mother 

 cell. This becomes two-layered before the archegonium is 

 mature, and is merged gradually into the massive pedicel, which 

 in the Mosses generally is much more developed than in the 

 Hepaticse, In the older archegonia the neck cells do not 

 stand in vertical rows, but are somewhat obliquely placed, 

 owing to a torsion of the neck during its elongation. From 

 the central cell the ventral canal cell is cut off, as usual, but is 

 relatively smaller than is usual among the Hepaticge. The 

 egg shows a distinct receptive spot, which is not, however, very 

 large. The rest of the egg shows a densely granular appear- 

 ance, and the moderately large nucleus shows very little colour- 

 able contents, beyond the large central nucleolus.^ The 

 terminal cells of the open archegonium diverge widely, giving 

 the neck of the archegonium a trumpet shape (Fig. 93, F). 

 Usually some of the cells become detached and thrown off. 



T/ie Emhyo 



The first (basal) wall in the fertilised ovum divides it into 

 an upper and lower cell, as in Sphagnum and Andrecea, and 

 the next divisions correspond closely to those in the latter. 

 In both cells a wall is formed intersecting the basal wall, but 

 not at right angles. This is especially the case in the upper- 

 cell, where a second wall strikes the first one nearly at right 

 angles, and establishes the two-sided apical cell by which the 



^ It is perhaps questionable whether this mass is really the nucleolus. It may be 

 composed in part of closely aggregated chromosomes. 



