40 BOTANICAL GAZETTE [JULY 
After the chromosomes have reached their full size, the nucleoli 
fragment, the fragments usually staining with gentian-violet. 
Soon the entire nuclear cavity becomes filled with granular matter 
staining with gentian-violet, and at this period the central 
portions of the spindle appear suddenly as the granular matter 
disappears. A few early spindles were noted in which this central 
portion did not seem to consist of sharply defined fibers. While 
such an appearance is often due to faulty methods, the sharply 
defined fibers in other figures in the same preparation favor the 
inference that these undifferentiated portions represent stages in 
the transformation of nucleolar matter into spindle fibers. In our 
opinion, these phenomena support Strasburger’s (33) theory that 
the nucleolus contributes some of the material for the spindle. 
Observations on the chromatin were merely incidental, but it is 
certainly safe to say that Pellia, in spite of the small size of its nuclei, 
is a favorable object for such study. As has just been mentioned, 
the nucleolus probably contributes something to the substance of 
the chromosomes. Although the chromosomes are small, they 
can be distinguished very early and seem to lose their identity 
much later than is usually the case. Mitoses in the venter of the 
archegonium show a longitudinal splitting of the chromosomes 
before the breaking down of the nuclear membrane, while in the 
germinating spores the splitting occurs much later. 
The number of chromosomes in the gametophyte, as counted 
in the germinating spores and in theactively dividing region of the 
thallus, is eight. This number, however, is far from being constant. 
Both Farmer (10) and Davis (7) report occasional irregularities. 
In the present study, a few nuclei were found with only seven 
chromosomes, and nine chromosomes were counted in more than 
a dozen cases (fig. 20). Long spindles upon which the chromo- 
somes are irregularly arranged are not infrequent, and it seems 
probable that such a mitosis might result in an unequal distribu- 
tion of the chromosomes, and thus account for variations from 
the typical number (fig. 8). 
THE THIRD MITOSIS IN THE GERMINATING SPORE. 
While considerable attention was given to the third mitosis, 
an extended description is hardly necessary. Prominent asters 
