Some Problems of Reproduction: a Comparative Study of ...

SOME PEOBLBMS 01 REPRODUCTION. 33
canal-cell." The latter elongates with the neck of the growing
archegonium which it occupies and fills, and by repeated'
bipartitions forms a file of cells (a multiple of four) which are
also termed " neck canal-cells." The proximal cell (central
cell) occupies the belly of the archegonium, enlarging with it,
but undergoing no further division till its maturity. Then
this central cell divides into two, the lower rounding off as
the oosphere, the upper undergoing mucous degeneration
like the neck canal-cells, and termed the " belly canal-cell."
Sometimes these two sister-cells are equal, but usually the
belly-cell is much smaller. Obviously both are gametes, the
former functional, the latter degenerate.
The next question that arises is this :—What are we to regard
as the "oogonium"—the central cell, the inner cell,
or the initial cell of the archegonium? The divisions of the
last are too closely allied to those which form tissue-cells
elsewhere; and of this nature are the majority of its broodcells
forming the wall of the oogonium, so that it would be
rather strained to call the initial cell a gatnetogonium. The
second alternative would seem most natural: to regard the
inner cell as a gametogonium, and the neck canal-cells as
degraded gametes (or rather their offspring). For though the
growth of these is concurrent with that of the cells of the
neck and accompanied by numerous divisions, yet the horizontal
septa are not coplanar with those of the neck wall, and do
not complete with these the schema of orthogonal trajectories,
which they should do if they belonged to the same system
of tissue-cells; their number is always a multiple of four; and
while the cells forming the oogonial wall have a prolonged
life, that of the canal-cells is limited, as in most gametes.
Again,the antheridium is formed from a single initial cell similar
to that of the archegonium, and similar divisions mark off its
wall-cells from a single central cell. The latter forms a
complex of cubical spermatocytes only, by repeated bipartition,
the cell-walls intersecting at right angles; and the cell body
of each spermatocyte is converted into a biflagellate spermatozoon,
a small portion of the cytoplast remaining unutilised
VOL. XXXill, FART I.—NEW SEE. C