On the Pithophorace.e. 



69 



inclosed spores are the greatest of all; they are on an av. *£■ /x. The limits of 

 variation are indicated by \^ ||g jw. 



Affinities and Differences. This species is distinguished from its nearest rela- 

 tions, P. polymorpha nob. and P. Zcllcri (v. Mart.) nob. by considerably greater 

 dimensions and particularly by a stronger ramification. The cells of the principal 

 filament carry here three (or even four) branches in a whorl, and branches of the 

 3:rd degree occur regularly. 



Having now described those species of Pithophora which I have seen both in 

 a fertile and in a sterile state, it remains to say a few words on a Pithophoraceous 

 plant which I know only as sterile. It is the australian Pifhophora mentioned above, 

 which has been communicated to me by D:r A. Grunow. According to the infor- 

 mation kindly given by D:r A. Grunow it has been gathered by D:r E. Gr^effe 

 in two localities, both situated in Upolu, one of the isles of Samoa. One of the 

 localities is running fresh water, the other is Mangrove-swamps with slightly brackish 

 water on a muddy ground. As the specimens brought from the two localities show 

 some small differences, I will describe each local form separately. 



The form brought from the fresh water locality has branches of two 

 degrees, which are sometimes placed in pairs opposite to each other, but most fre- 

 quently singly. The branches regularly proceed from their supporting cells a small 

 space below their top. The thickness of the principal filament varies between 100 

 and 110 /x, that of the branches of the l:st degree between 90 and 100 fx, and 

 that of the branches of the 2:d degree between 80 and 95 p,. The length of the 

 common vegetative cells is generally rather considerable. The length varies between 

 10 — 30 times the thickness. In one specimen I have observed cells which very 

 strongly call to mind real Pithojthora-spores by their very much smaller length, 

 their greater thickness and their greater abundance of chlorophyll. The cause of 

 my not being able to recognize them as such with certainty is l:o that the cells 

 which ought to be the sister cells of the spores (the subsporal cells) are not parti- 

 cularly poor in chlorophyll, 2:o that the length of the supposed spores varies very 

 much, and 3:o that they have almost all developed (not merely support) branches. 

 If they be really spores, they must be supposed to have proceeded in the same 

 manner as the spores which I have represented pi. 6, fig. 6, belonging to Pithophora 

 oedoyonia (Mont.) nob. They would then have germinated while yet remaining 

 attached to the mother plant, in the same manner as prolific cells, by bringing 

 forth lateral branches. The thickness of those cells varies between 100 and 150 /x, 

 and their length between 175 and 460 (x. 



The form from the Mangrove-swamps has branches of at least two degrees, 

 which are placed singly, opposite in pairs, or now and then three in a whorl. The 

 branches sometimes proceed from the supporting cells a small space below their 

 top, but often at the very top. l ) Most frequently the branch is supported by a 



*) This, together with other things, is the cause why I am not quite convinced of 

 this species belonging to the genus of Pithophora. 



