38 



Veit Bkecher Wittrock. 



ought to be placed nearest to Pithophoraceos 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 Pitliophoracece, we 

 find a form of this description only in one group of plants, that of the 

 Vaucheriacece; and, within this group, only in two species, Vaiicheria 

 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 x ) takes place in a manner which calls to mind, 

 in some of its phases, that of the Pithophoracece. Here, as well as in 

 Pithophoracece, 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- 

 phoracece, a quantity of the chlorophyll-coloured protoplasm passes into 

 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: l:o and essentially, that the cell 

 rich in chlorophyll and formed in the manner now described does not 

 grow into a spore in Vaucherice, although it does in Pithophoracece, but 

 in Vaucher'ue it grows into a mother cell of a spore, formed within it 

 through cell-rejuvenescence; 2:o and as a consequence of the preceding, 

 that the spore in Vaucherice does not (as in Pithophoracece) make use of 

 the membrane of the mother cell, but forms one for itself; 3:o that the 

 spore does not (as in Pithophoracece) 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 (in analogy with the 

 emission of the zoospores from their mother cells in other Vauche- 

 rice); 4:o that the spore is always formed terminally in Vaucherice, in 

 contradistinction from what is the case in Pithophoracece ; and 5:o that 

 no subsporal cells devoid of chlorophyll occur in Vaucherice,, as is the 

 case in Pithoplioraeece, because the vegetative system consists in Vaucherice 

 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. 2 ) If we now continue our investigations by 



! ) Compare Witth. Utveckl. af Vauch. pag. 34 and 35; and Walz Bcitr. z. 

 Morph. (1. Vouch, pag. 132 and 133. 



-) See Wittk. 1. c. plate 2, fig. 7. 



