Rickett.—Fertilization in Sphaerocarpos. 241 
of Phase 5 are seen to be beginning here—a grouping of the chromatic 
material into the general shape of a continuous thread. In Series A most 
of the cases of fertilization 48 hours after flooding, a time which falls within 
Phase 5 in the other series, belong here as regards the structure of their 
nuclei. 
In the cytoplasm the tendency towards an alveolar structure becomes 
more marked. There are also many cases showing the coarsely reticular 
structure described under the second phase (Fig. 8). Few eggs, however, 
show the fine, more homogeneous structure characteristic of the first phase. 
Some of the preparations belonging to this period show the beginning of 
a phenomenon which is characteristic of the next phase, and which will be 
more fully discussed later. This is a massing of a more dense and finely 
divided material in the cytoplasm near the poles of the female nucleus, 
leaving the rest of the cytoplasm often distinctly alveolar. The beginning 
of this process is shown in Figs. 9 and 12. Very rarely indications of this 
change are found in earlier stages. In Series C several eggs showing the 
characteristics of the second phase, and fixed only a few hours after flooding, 
show areas in the cytoplasm, near the poles of the nucleus, the substance in 
which seems more homogeneous than the rest of the cytoplasm and stains 
more lightly. Mention has already been made, under Phase i, of a case in 
which the cytoplasm was denser and of a finer structure immediately around 
the nucleus, more open in the peripheral region. The most remarkable 
instances of the localization of a differentiated portion of the cytoplasm were 
found in Series A , 48 hours after flooding. In these cases there is an aggre¬ 
gation in the cytoplasm, in the regions normally occupied by the polar caps 
just described, of distinct granules of considerable size. They stain blue, 
and are conspicuous in the preparations. They are usually arranged in more 
or less regular rows radiating out from the poles of the nucleus. They are 
connected by a delicate system of slender threads. The whole structure 
seen under the low power of a microscope suggests at once two asters 
formed of radiating fibres ; however, there is no distinctly recognizable 
body present at the centre of the radiations, either in this or in earlier or 
later stages. This condition is shown in Fig. 11. It is not universally found 
during this phase even in Series A, and is met with only rarely in the 
other series. As it sometimes occurs in later stages, further discussion 
of it will be postponed. 
The condition of many of the female nuclei in eggs which show these 
cytoplasmic granules is peculiar. The contents are stained red instead of 
violet as usual, and are in the form of rounded bodies scattered throughout 
the nuclear cavity, with traces of a very fine reticulum. In Fig. 11 nine of 
these bodies are visible. The remainder of the same nucleus, seen in the 
adjacent section, shows several more. They have an appearance suggestive 
of small nucleoli, and recall the structures present in the nucleus in some of 
R 2 
