38 Vert Brecuer Wirrrock. 
ought to be placed nearest to Pithophoracee in regard to the reproductive 
system. Looking, to begin with, for a form of plants which would show 
a formation of spores reminding us of that of the Pithophoracew, we 
find a form of this description only in one group of plants, that of the 
Vaucheriacew; and, within this group, only in two species, Vaucheria 
geminata (Vauch.) Walz, and V. hamata (Vauch.) Walz. Only in 
these (as far as we know) have been found immoveable spores, formed 
neutrally (at least part of the other species have, we know, neutrally 
formed moving spores, so-called zoospores). The formation of spores 
in both these species*) takes place in a manner which calls to mind, 
in some of its phases, that of the Pithophoracee. Here, as well as in 
Pithophoracee, the proceeding is introduced by a slight widening of that 
part of the cell in which the spore is to be formed; here, as in Pitho- 
phoracee, a quantity of the chlorophyll-coloured protoplasm passes imto 
the widened part, and here also the part of the cell thus filled with 
chlorophyll is separated from the other part by a transversal cell-wall 
formed succedaneously. So far the resemblance goes. We will now 
observe the differences. These are: 1:o and essentially, that the cell 
rich in chlorophyll and formed in the manner now described does not 
grow into a spore in Vaucherie, although it does in Pithophoracew, but 
in Vaucherie it grows into a mother cell of a spore, formed within it 
through cell-rejuvenescence; 2:0 and as a consequence of the preceding, 
that the spore in Vaucheriw does not (as in Pithophoracew) make use of 
the membrane of the mother cell, but forms one for itself; 3:0 that the 
spore does not (as in Pithophoracew) remain for a long time united to 
its mother specimen, but is made free very soon by the dissolution 
of the environing wall of the mother cell Gn analogy with the 
emission of the zoospores from their mother cells in other Vauche- 
rie); 4:0 that the spore is always formed terminally in Vaucherie, im 
contradistinction from what is the case in Pithophoracee; and 5:0 that 
no subsporal cells devoid of chlorophyll occur in Vaucheriw, as is the 
case in Pithophoracew, because the vegetative system consists in Vaucherie 
of only one cell (but that a gigantic one), which commonly does, far 
from being exhausted by one act of spore formation, beget numerous 
spores and sometimes a more or less considerable number of oogonia 
and antheridia besides.*) If we now continue our investigations by 
1) Compare Wrrtr. Utveckl. af Vauch. pag. 384 and 35; and Watxz Beitr. z. 
Morph. d. Vauch. pag. 182 and 133. 
”) See Wirtr. |. c. plate 2, fig.-7. 
