324 SEMI-CENTENNIAL OF TORREY BOTANICAL CLUB 
centrospheres. А small amount of the same material also clings 
to the cytoplasmic fibers at the periphery of the cell. This dense 
cytoplasm may appear more or less alveolar at this stage. Prior 
to fertilization the whole cytoplasm of the egg has this consistency. 
The outer zone of the cytoplasm is coarsely vacuolar. The films 
between the vacuoles are very thin and delicate. A few larger 
and quite dense homogeneous granules are scattered through both 
zones of the cytoplasm. The egg nucleus and the nucleus of the 
antherozoid are plainly differentiated by their size and in FIGURES 
I, 2, and 3 are shown lying in the central part of the cell. In 
FIGURES I and 3 their nuclear membranes are in contact. 
In the dense cytoplasm at the opposite poles of the egg nucleus 
astral rays are seen converging upon small dense rounded bodies, 
the centrosomes (FIGS. 1 and 2). These rays extend long distances 
through the cytoplasmic ground substance. They may pass close 
to the nuclear membrane or may touch it. А fiber radiating from 
the centrosome at the upper part of FIGURE I touches the nuclear 
membrane of the antherozoid; another radiating from the same 
centrosome touches the outer membrane of the egg nucleus. The 
astral rays make up an open aster with few rays; but they are 
very definite fibers easily distinguishable from other cytoplasmic 
structures. Peripherally they end rather abruptly and have no 
conspicuous physical connection with any of the other elements of 
the dense cytoplasm. It is quite possible that there are other 
shorter and more delicate rays, but I have drawn only those which 
are plainly differentiated. All these fibers center on a centrosome 
which seems to be a single body. 
FIGURE 3 shows a slightly earlier stage of fertilization. A 
centrosphere lies above the egg nucleus, the rays extending to its 
membrane. FIGURE 4 is another section of the same egg and shows 
à second centrosphere. 
One or more large dense bodies lie among the astral rays 
a short distance from the center, but they do not constitute a part 
of the region on which the rays center (FIGURES 1—4). 
Centrosomes and asters have been demonstrated in the vegeta- 
tive cells of liverworts by Farmer and Reeves (’94) in the germinat- 
ing spore of Pellia epiphylla and by Van Hook (оо) in the cells 
of the stalk of the archegoniophore of Marchantia polymorpha. 
