1921] WALKER—GAMETOPHYTES OF EQUISETUM 383 
mother-cells are not yet differentiated. Two cells to the right of 
it is the venter of an archegonium surrounded by its jacket cells 
and containing a mature egg cell. Above at a are the neck cells 
in oblique section. 
Figs. 12 and 13 are near sections, cut horizontally. In fig. 12 
are shown twelve antheridia in various stages of development. 
Fic. 3.—E. laevigatum (vertical section): at left young antheridium; at right 
archegonium with egg; below a neck cells cut obliquely; X 380. 
In the smaller lobe only two cells from a young antheridium is 
the neck (a) of an archegonium, whose venter containing a mature 
egg is shown in a deeper section, fig. 13 below a. Fig. 14 shows a 
vertical section of an archegonium containing a young sporophyte. 
Fig. 15 is a vertical section showing two mature antheridia at the 
left. Directly below a and a are the necks of two old archegonia 
that have failed to be fertilized. In fig. 16 above is a mature 
antheridium and a very young one. At the extreme left (B) and 
