166 BOTANICAL GAZETTE [SEPTEMBER 
starch grains. The wall cells of the sporangium do not at this time, 
as in some sporangia (Ophioglossum, for example), contain starch, 
but are relatively poor in cytoplasm and cytoplasmic inclusions. 
There is relatively little change in the cytoplasm of the sporogenous 
tissue as growth advances, except that it grows gradually less dense 
until at the time of the formation of the young spores there is almost 
no stainable substance left. 
The nuclei of the sporogenous cells (fig. 7) previous to the mother 
cell stage show a structure that is very like that of the cytoplasm just 
described, except that it is denser and there is more of a tendency 
to aggregate itself into disconnected masses. There are one OF 
more large nucleoli present in the nucleus at this stage, as there 
seem to be in the resting nuclei of all the stages of all the tissues 
examined. 
As the nucleus approaches division, the nuclear substance begins 
gradually to arrange itself into filaments or strands (fig. 8) which 
may end freely or anastomose with other filaments or masses. About 
the same time the hitherto nearly uniformly staining material begins 
to stain differentially, so that filaments seem to link together knots © 
more deeply staining material. Whether this indicates a difference 
of substance, as some think, or merely a difference in the state of 
aggregation, as has been recently maintained by several authors, 
cannot be said with certainty. However, the gradual derivation of 
this structure from the preceding one, in which everything seems 
homogeneous, would certainly point to the latter interpretation as the 
correct one. During this time the nucleolus (or nucleoli) gr adually 
loses its density, as shown by the staining reactions. It continues ' 
do so until it finally does not stain at all or has disappeared entirely: 
Fig. 9 shows a surface view of a nucleus in which the filaments have 
become more regular and somewhat thicker. In fig. 10 is esate . 
spirem, into which the filamentous stage gradually passes, 2 W 
the deeply staining knots on the spirem are unusually promin : 
The figure shows nearly all of the spirem that was included 2 
3-# section; therefore it probably contains one-third to one-h 
of the entire spirem, since the nucleus is about 7X10 -- In ae 
cases the spirem consists of darkly stained masses connected by we 
smaller threads, and in others, as shown in fig. 10, by broader st 
