Wilson . — Spermatogenesis in the Bryophyta . 439 
the side, and when circular in outline it is described as seen from above or 
below. After the division is completed each spermatid shrinks slightly, 
but retains its original shape ; the wall separating the individuals of each 
pair does not swell, but remains thin and sharp in outline (Fig. 71 ). At 
this stage the appearance of the antheridium is very characteristic ; the 
pairs of spermatids are easily distinguished since each is separated from 
the neighbouring groups by the greatly swollen mucilaginous walls of the 
mother-cells ; between the individuals of each pair there is a small space in 
which the thin wall separating the two cells is found. The swollen walls of 
the mother-cells, as well as the walls separating the spermatids, are easily 
stained with orange G and colour deeply with Congo red. They consist 
at least partially of pectic substance, since they are also stained with 
ruthenium red. 
The occurrence of a wall between the spermatids of each pair is of 
especial interest. The wall was figured by Buchtien (15) and Guignard 
(26 A) in Pellia epiphylla , but is omitted by Campbell (16) in a drawing of 
the paired spermatids of the same plant. Ikeno, after special search, failed 
to find a similar wall in Marchantia polymorpha , and similar results have 
been obtained by Bolleter (13) in Fegatella conica , Humphrey (30) in 
Fossojnbronia longiseta and Aneura , and Lewis (43) in Riccia natans. 
In view of the diversity of the above statements, preparations 1 of the 
developing antheridia of Aneura pmgius were examined in order to deter- 
mine whether in this plant a wall is present at a similar stage. The 
material had been fixed in acetic alcohol and the preparations were stained 
with Flemming’s triple stain or with Heidenhain’s haematoxylin and 
orange G. With either of these stains a wall can be clearly distinguished 
separating the spermatids of each pair. The antheridia of this plant closely 
resemble those of Pellia ; the spermatids are of a similar shape, and the 
pairs show the same space relationships. In consequence, both in Pellia 
and Aneura , this wall does not divide up a cubical mother-cell, but one 
which is approximately spherical in shape. This is also the case in Makinoa 
crispata, in which Miyake (44) states that the cells in the antheridium 
assume a more or less spherical form just before the last mitosis. Although 
there is no doubt that this is the equivalent to the final division described 
by Ikeno (32) in the antheridium of Marchantia , yet it is obvious from the 
account just given that it cannot, at any rate in Pellia and Aneura , be 
described as ‘ diagonal \ In these latter plants the form of the mother- 
cells is determined by their early separation, while in Marchantia no such 
process goes on and the cells remain cubical. In Pellia and Aneura , even 
if the division is phylogenetically ‘ diagonal ’, yet, ontogenetically, there is 
little evidence of it. 
1 The preparations in question were made by Professor Farmer, F.R.S., who has very kindly 
allowed me to have the use of them. 
Gg 2 
