448 Woodburn.—Spermatogenesis in 
chromatin is not all retained within the nuclear membrane, but that at least 
a considerable portion is extruded into the cytoplasm, no agreement has yet 
been reached as to the exact fate of this nuclear material after passing out 
into the cytoplasm. The problem seems to be more difficult than that met 
with in the Hepaticae, where the nucleus, in the majority of cases observed, 
remains entire and lengthens out bodily in the direction taken by the 
blepharoplast. Wilson (6) has, however, cited Pellia epiphylla as showing 
much the same condition as he found in Mniurn hornum and Atrichum undu - 
latum in the Musci. My observations on Mniurn affine , var. ciliaris , lead me 
to believe that during this stage the nucleus does not remain as sharply 
differentiated as in the case of the Liverworts, but that there is a tendency 
for the nuclear membrane to disappear, allowing possibly a more intimate 
association between nuclear and-cytoplasmic material (Figs. 13 and 14). 
The nuclear content becomes very finely granular, staining almost homo¬ 
geneously (Figs. 12 and 14). In Fig. 12 are shown two lumps which may 
represent nucleoli ; the remainder of the nucleus stains homogeneously. 
As development proceeds, the nucleus becomes even more smoothly and 
evenly granular (Figs. 12 and 14), these lumps or nucleoli as well as distinct 
chromatin granules disappear, the nucleus stretches out in a direction 
parallel with the blepharoplast and at the same time loses to a certain 
extent its very distinct outline. Occasionally very dark staining lumps 
may be observed in the cytoplasm, and the nuclear part may also be some¬ 
what vacuolate (Fig. 13). The nuclear membrane, if present, stains very faintly 
and can be scarcely differentiated in Figs. 13 and 14. Figs. 10, 11, 12, 13, 
14, and 15 represent quite closely consecutive stages, so that the position 
of the nucleus in each case can be readily determined. Fig. 15 represents 
a well-advanced stage in which the nucleus and doubtless also the ble¬ 
pharoplast have formed one complete turn, while the latter may be readily 
distinguished from the former. Fig. 21 represents a stage not greatly 
in advance of that shown in Fig. 15. The cause of the difference in appear¬ 
ance may be due either to the fact that Fig. 15 represents a sperm killed and 
fixed inside of the antheridium, while the one shown in Fig. 21 had been 
allowed to escape in a drop of water on the slide and then very suddenly 
killed with 2 per cent, osmic acid, or the former may probably represent 
a sperm normally smaller. Either one or both explanations together are 
quite plausible. Cilia could easily be seen in Fig. 21, but they could not 
be detected in Fig. 15. Figs. 10,11, 12,13, 14, 15, and 16, while presenting 
certain features which will be discussed later, demonstrate clearly two 
or three prominent things. The blepharoplast grows as a cord or band 
around one side of the cell. The nucleus moves to this side of the cell and 
lengthens in a course parallel with that taken by the blepharoplast. While 
these changes in form are taking place, the internal structure of the nucleus 
changes from a coarse open network to a very smooth, granular, homo- 
