105 
all the spores of the sporangium, can be readily distinguished 
from the surrounding somatic cells. It is larger, and the chroma- 
tin of the nucleus stains much more deeply than that of the other 
cells. The chromosomes are large and distinctly looped, and in 
the metaphase of karyokinesis they are split by’a longitudinal 
division (Fig. 17). After each division the daughter-nuclei pass 
into the resting stage, during which the cell-walls are com- 
pletely formed and each daughter-cell becomes completely sepa- 
rated. The resting stages are comparatively long and the division 
stages short. 
1. The growth-period. 
After the sixteen primary sporocytes are formed the nuclei 
pass as usual into the resting stage (Fig. 1). The nuclei are at 
first comparatively small (10.3 » in diameter), the chromatin-reti- 
culum does not stain intensely, and there are usually from one to 
threeor more nucleoli in each. Meantime the tapetal cells degener- 
ate, giving room for growth of the reproductive elements. This 
growth must begin very soon for the cells in the resting stage 
(Fig. 1) are not frequently found. When fully grown, the nuclei 
measure about 14.5 in diameter, an increase of nearly 50 per 
cent. During this enlargement the chromatin reticulum is con- 
verted into a delicate moniliform spireme. This is a single thread 
of chromatin, very much coiled and interwoven and at first distri- 
buted evenly throughout the nucleus (Fig. 2). From this condi- 
tion of extreme delicacy and expansion the chromatin soon passes 
into. a stage of greater localization and the spireme becomes 
thicker. Evidence of the beginning of concentration can be seen 
in Fig. 2 an early stage, where the nucleolus has not disappeared. 
In a later stage, to which Farmer has given the name “ Synapsis,” 
the meshes are drawn towards one side of the nucleus into a much 
more compact chromatin mass (Fig. 3). This mass next becomes 
loosened and the filaments more or less isolated. In exceptionally 
favorable preparations the spireme in this stage is seen to be 
double (Fig. 3 x). 
The concentration of the chromatin at the same time with the 
thickening of the spireme seems to indicate: a coalescence and 
union of the formerly distinct granules of chromatin in the deli- 
cate moniliform spireme. 
