1912] GRIGGS—RHODOCHYTRIUM 149 
stained, one or sometimes two delicate connections could be seen 
between this basal body and the nucleus (fig. 34). The origin of 
the basal body was not made out. Apparently it appears only 
during the maturation of the spore, for it was not observed in 
earlier stages (figs. 32, 33). 
The primary nucleus 
Although the youngest cysts observed are many times larger 
than the zoospores from which they originated, their nuclei show 
comparatively little enlargement. But they differ somewhat in 
character from the nuclei of the zoospores in that the concentration 
of the chromatin, which, as shown above (figs. 32-37), begins in 
the maturing zoospore, has been completed, forming the karyosome, 
which is the most conspicuous element of the nucleus. But the 
karyosomes of the young cyst have not acquired the character 
of the later nucleoli. From the irregularity of their shape they 
appear to be merely plastic masses of chromatin (fig. 42). They 
soon take on the definite spherical form of mature nucleoli, and at 
the same time probably become firmer, inasmuch as in the later 
vacuolate stages the rind is strong enough to retain its shape after 
most of the contents have been withdrawn. The linin reticulum 
seen in the sporangial segments probably persists on the periphery 
of the nucleus in the youngest stages, but it loses its affinity for 
stains and is exceedingly difficult to see satisfactorily. All that can 
be made out with certainty in most of the nuclei is a few delicate 
linin strands stretching from the karyosome to the nuclear mem- 
brane (figs. 1, 13), or, in optical section, a number of peripheral 
granules (figs. 2, 12), which probably represent cross-sections of 
the similar strands that compose the reticulum, but are too faintly 
stained to be visible in surface view. 
No differences between the nuclei of the incipient zoosporangia 
and of resting spores were detected. From the youngest stages on 
they undergo the same development, which in one case leads to 
mitosis and in the other to shriveling preparatory to the long 
dormant period. 
The most conspicuous of the changes in the nucleus is its increase 
in size. From 4 or 5 it grows with the cyst until it may reach 
