12 I 
Steil. — Apogamy in Nep hr odium hirtipes , II k. 
stage retain their position in the plate or pass only a short distance towards 
the poles of the spindle. Fig. 26, PI. VI, represents a dividing nucleus in 
which the chromosomes have passed only a short distance towards the poles. 
The distribution of the chromosomes in this case may suggest a polar view 
of an equatorial plate stage, but in such a view and at an early stage the 
chromosomes present a more compact arrangement. Spindle fibres were 
demonstrated to be present in some cases at this time. From an examination 
of other sections of the same nucleus, it is probable that neither a kidney- 
shaped nor a dumb-bell-shaped nucleus will be formed from such a nucleus. 
Frequently a nearly spherical resting nucleus was found in a sporangium, 
while adjacent to it was a nucleus of the kidney-shaped type. The 
spherical nucleus in this case may have resulted from an incomplete nuclear 
division in which the chromosomes of the equatorial plate passed only a 
short distance towards the poles. 
A number of nuclei in a sporangium become spherical at an early stage, 
and some sporangia were found in which the nuclei of all eight of the 
sporogenous cells were spherical, and in this case each nucleus was in the 
resting condition. Two assumptions can be made in regard to the origin of 
such nuclei. The resting nuclei of the first eight-celled stage may npt divide 
and function as the nuclei of the spore mother-cells, or they may begin to 
divide, but the chromosomes may not pass to the poles. From what has 
been stated in regard to the history of the chromosomes in the equatorial 
plate, it is very probable that the latter assumption is true. In some 
sporangia, as previously stated, all the nuclei are either kidney-shaped or 
dumb-bell-shaped, while in other sporangia the nuclei vary from the 
spherical to the kidney or dumb-bell forms. It would not, therefore, be 
surprising to find a sporangium all of whose nuclei were spherical in form, 
even though an incomplete division had occurred in each. 
Spindle fibres were in some instances stained with difficulty, and at first 
were overlooked. These fibres are shown in Figs. 24, 2.5, 27, 28, 29, of 
PL VI. In the cell shown in Fig. 28 a cell plate was already formed 
although no nuclear membrane was present. Sometimes the fibres are well 
developed, but there is no indication of a cell plate (Figs. 25 and 27, PI. VI). 
As the different longitudinal sections of nuclei indicate, spindle fibres are 
never present on the convex side of the nucleus. In a number of instances 
spindle fibres appeared to be absent even on the concave side of the nucleus. 
In some cases, on account of the distribution of the fibres, the plate formed 
on the spindle did not extend to the nuclear membrane ( c , Fig. 27, PI. VI). 
In the majority of cases, however, the plate extends from the wall of the cell 
to the nuclear membrane (Figs. 29-33, VI). In some instances the fibres 
are poorly developed or quite absent. This seems to be frequently the case 
when the nuclei- are somewhat irregular in form. When spindle fibres are 
present a cell plate is often produced and a distinct cell wall is formed later, 
