Igto] YAMANOUCHI—CHROMOSOMES IN OSMUNDA 3 
manner has no possible chance of including achromatic substances, 
so that the only substances within the nuclear membrane are the 
chromatin and substances derived from chromatin. This is in 
accord with GREGOIRE and WyGaerts’ results (5). 
At the beginning of the process of vacuolation the chromosomes 
do not lie strictly parallel, but converge toward the pole (fig. 1). 
Naturally, chromosomes thus aggregated leave unoccupied space at 
both their convergent and divergent ends; and during the process of 
vacuolation a nucleolus always appears in the young nucleus at or 
near the vacant space in the nuclear cavity beyond the convergent 
ends of the chromosomes (jig. 2). Such a manifestation of polarity 
is usual in the telophase of typical mitosis. 
By careful observation the limits of each of these chromosomes 
are discernible for some time. When vacuolation accompanied 
by nuclear growth has proceeded still farther, and the chromatin 
networks resulting from the individual chromosomes have become 
connected one with another, so as to appear like a single network 
irregularly distributed throughout the nuclear cavity, the polarity 
is no longer recognizable (fig. 3), and this is regarded as the resting 
state of the nucleus. 
The nucleus in the resting state is a reticulum, consisting of 
tagged clumps and strands of irregular shape. The clumps and 
Strands are chromatin; the former are more deeply colored by 
Stains than the latter, not because they are substances of a different 
nature, but simply because of differences in density. 
The number of the chromatin clumps in the resting nucleus in 
- Osmunda is large and variable, always far greater than the number 
of chromosomes. Without doubt, certain areas of these clumps 
and strands may represent the limits of certain chromosomes in the 
resting condition, but even after tracing a very close series of stages 
from the early telophase to the resting nucleus, the limits of individ- 
ual chromosomes in the resting reticulum are difficult or impossible 
to discern. 
FORMATION OF CHROMOSOMES IN VEGETATIVE MITOSIS 
Tn early prophase the chromatin of the resting state, composed 
of fine ragged clumps and strands, becomes more and more evident 
