124 SteiL — Apogamy in Nephr odium hirtipes , Hk . 
cells had been formed in a sporangium. In one sporangium three 
undivided mother-cells and six tetrads were found. There must have been 
at an early stage, therefore, nine spore mother-cells. One of the eight 
sporogenous cells which ordinarily undergo the incomplete division already 
described presumably completed its division in this case, and thus the 
additional spore mother-cell may have resulted. In one other instance more 
than the usual number of tetrads was found in a sporangium. In this case 
there were eleven tetrads, six showing evidences of incomplete divisions, 
and five of complete divisions. Fig. 53, PI. VII, represents one of the tetrads 
with incompletely divided cells. In the plane of the section only one of the 
cells and its nucleus indicated that the divisions never had been completed. 
However, the other cell and its nucleus showed similarly that incomplete 
divisions had occurred. If three of the eight sporogenous cells which as a rule 
undergo the incomplete divisions described divided, three additional cells 
would be produced. The other five cells would undergo the usual divisions 
in the formation of the tetrads ; but six of the cells, it may be supposed, 
would show abnormalities in the divisions. From such a single instance it 
is, of course, unsafe to draw any positive conclusions. The two sporangia 
here described were the only ones which afforded evidence that a complete 
division of one or more of the eight original sporogenous cells may 
occasionally occur. 
Sometimes, on account of the shape of the spore mother-cell and its 
nucleus, the chromatin material may be divided during synapsis into two 
nearly equal masses. In one instance two nearly distinct chromosome 
groups were observed during diakinesis in a dumb-bell-shaped nucleus. As 
a result of the usual divisions eight nuclei may be produced. When the 
spore mother-cells are kidney-shaped or dumb-bell-shaped, the chromosomes 
during the anaphase of the heterotypic division at one or both of the poles 
may occasionally be separated into two groups (Fig. 49, PI. VII). The 
separation of the chromosomes in this instance is clearly brought about by 
the indentation of the mother-cell resulting from the original incomplete 
division. Each of the three nuclei represented in this figure may divide 
(Fig. 50, PI. VII) and six spores may be formed. Fig. 52, PI. VII, shows 
five of the six nuclei which result in such a case. Several metaphase figures 
were found in the preparations similar to that shown in Fig. 50, but only 
one spore mother-cell containing three anaphase figures was observed 
(Fig. 51, PI. VII). That the two smaller division figures represented in the 
figure resulted from a division of one of two groups of chromosomes pro- 
duced during the anaphase of the heterotypic division cannot be stated with 
certainty. When there are two indentations in the spore mother-cell there 
might conceivably be produced during the anaphase of the heterotypic 
division four chromosome groups, and in consequence of the following- 
division eight spores might be formed from a single spore mother-cell. No 
