244 BOTANICAL GAZETTE [APRIL 
The plasma-membrane which bounds externally the thin primordial 
utricle has evidently been infolded at this point, thus forming a deep, 
narrow furrow. The young partition-wall which is being deposited in 
this groove can not be seen in the figure. We note further in fig. 18 
that the two nuclei which are shown are in a state of rest; in fact, 
nuclear division does not occur at all during the pre-fructifying. 
period characterized by the formation of conidiophores. And in the 
same figure we also see that the nuclei are separated by a wide 
vacuolar space from that part of the cell in which division is pro- 
ceeding, and that they are joined to the active region only by a nar- 
row cytoplasmic connection. It seems reasonable to suppose that 
cell-division, in this instance, is a cytoplasmic phenomenon and is 
merely remotely or indirectly subject to nuclear control. In fig. 18 
it will be noted that the stain is deepest at the inner margin of the 
cleft, showing that in this innermost region in which the new wall is 
being laid down, the cytoplasm is densest and most active. 
Fig. 19 shows a similar ring-formed septum partly across a young 
vegetative hypha, at a slightly advanced stage of growth. A bridge 
of cytoplasm is next thrown across the vacuolar space before the wall 
is completely formed, as is seen in fig. 20. This figure brings out 
most clearly the region of greatest activity. In the preparation, the 
stain (iron haematoxylin) was well washed out, so that the cytoplasmic 
bridge as well as the ring-formed wall are left unstained except at the 
innermost part of the furrow, where a small black granule is con- 
spicuous. In this dark region the new wall is evidently being depos- 
ited. Immediately on the throwing across of the cytoplasmic bridge, 
the greater turgor of the cell below ordinarily causes the partition to 
bend outward toward the outer end of the hypha (fig. 20). This 
bending is also quite noticeable after the final completion of the par- 
tition wall ( jig. 17). 
A study of these figures might lead to the conclusion that we have 
here a process exactly similar to that already described for certain 
other fungi (see HaRPER, ’99, p. 506), in which the cleavage furrow 
first cuts across the cell and the wall follows later. One would in fact 
naturally come to this erroneous conclusion, since every one of the 
drawings mentioned above, except perhaps figs. 19, 21, shows clearly 
the circular furrow, but no sign as yet of the ring-formed septum. 
