Black. — The Morphology of Riccia Frostii , Aust. 517 
Fig. 18. The nucleus is large, and the chromatin is collected in a cord or 
short segments. A fine network is seen in the nucleus besides the densely 
staining material. After fertilization, the venter of the archegonium, which 
is one cell thick, undergoes division, the cells at the base usually dividing 
first. 
The Sporophyte. 
The first division-wall in the fertilized egg is usually oblique, although 
inclined to be at right angles to the axis of the archegonium. Campbell, 
Garber, and Lewis report this division as usually horizontal, although some- 
times oblique. The second division may be parallel to the first, resulting 
in a three-celled embryo, as in Fig. 19, or it may be at right angles, 
resulting in a globular embryo. Later divisions do not always follow 
the order described by Campbell, but the embryo gradually develops by 
irregular cell-division. The embryo, even when consisting of thirty or forty 
cells, may be oval (Fig. 21), but is usually globular (Fig. 20). The amphi- 
thecium is developed according to Campbell ; sometimes this tabular row 
will be cut off early, or it may not be differentiated until quite late. In 
a growing embryo, several cells may be found in different stages of division, 
as seen in Figs. 24 and 25, which are from the same sporophyte. One is 
a late telophase with the chromatin in an apparent cord (Fig. 25). The 
other is a polar view showing sixteen chromosomes (Fig. 24). 
By the time the spore mother-cells are formed, the amphithecium is 
partly disorganized. The inner layer of the sporangium wall is beginning 
to collapse, while the outer one appears comparatively firm. Many chloro- 
plasts are seen in this layer (Fig. 23). The spore mother-cells round up, 
not entirely filling their cell cavities. The spore mother-cells do not com- 
pletely fill the sporangium again until the spore tetrads are formed. The 
mucilaginous substance with which the spore mother-cells are surrounded 
stains homogenously with various stains, having great affinity for gentian 
violet and Bismarck brown. The nucleus of the spore mother-cell possesses 
a definite nucleolus. Lewis reports no definite nucleolus for Ricciocarpus 
licit cms, unless the mass of chromatin found in dividing nuclei be interpreted 
as such, but in Riccia Frostii these two stages seem to be differentiated. 
In material fixed with chrom-osmic-acetic acid mixture, oil drops are 
abundant in the spore mother-cell as black granules varying in size. 
Besides these, a dense network of lighter staining material fills the cell. 
The cell membrane is delicate. All the cells from the fertilized egg become 
spores except the amphithecium. 
Anomaly. 
The only abnormality observed is that in Fig. 22, in which the sporo- 
phyte has been affected by a bacterial organism. The neck of the arche- 
gonium is plugged by its mucilaginous contents. Below this the mass of 
N n 2 
