30 Lang . — Prothalli of Ophioglossum pendulum 
produces the group of spermatocytes (Figs. 18-20). The 
first divisions in the inner cell are as a rule anticlinal, followed 
by a periclinal division in each of the resulting segments. 
The mature antheridia do not project from the surface of 
the prothallus and are only conspicuous on external examina- 
tion by reason of the mass of spermatocytes, showing 
through the thin outer wall (Fig. 7). In vertical section 
(Fig. 21) the large oval mass of spermatocytes, the greatest 
diameter of which is parallel to the long axis of the branch, 
is seen to be surrounded by a limiting layer of flattened cells. 
This layer and the one outside it are never invaded by the 
hyphae of the Fungus (Fig. 23). The true wall of the 
antheridium is of small extent, flat or very slightly convex. 
It is a single layer of cells thick 1 and in surface view shows 
a triangular opercular cell (Fig. 22), which breaks down to 
give exit to the spermatozoids. The latter were unfor- 
tunately not examined when the material was collected, and it 
has not been found possible to ascertain their exact form or 
the number of cilia they possess from the study of those still 
in the antheridium. 
The archegonium also arises from a single cell, which 
divides into three by two periclinal walls (PI. II. Fig. 24). 
The outermost of these gives rise to the neck, the middle to 
the central series, while the lowest of the three is the basal cell. 
The basal cell usually undergoes a few divisions, but its out- 
line remains clearly recognizable in mature archegonia. The 
cell which gives rise to the neck divides by anticlinal walls into 
four ; each of these gives origin to one of the four rows of cells 
(Fig. 27) of which the neck consists. There are as a rule four 
cells in each row, but sometimes only three. The neck hardly 
projects above the general surface (Fig. 25). The central 
cell early divides into two, the upper of which insinuating 
itself between the neck-cells is the neck-canal-cell (Fig. 25). 
This becomes binucleate (Fig. 26), but no cell-division has 
been observed to follow, nor has the division of the middle 
1 Exceptionally the cells of the wall undergo a periclinal division in old 
antheridia. 
