78 



Veit Brecher Wittrock. 



upper end first the great spore marked s and after that the small spore marked 

 s", which are consequently a pair of twin spores. At the same time another 

 mother cell, situated above the parting-wall, w, has formed in its lower end 

 the spore marked sb, which, consequently, has not the same mother cell as 

 the two others. The parting walls w' and iv" have been arrested in their 

 development, and remain incomplete. 

 » 9. An inclosed spore, ripe. Observe the thickness of the spore membrane 

 when compared to that of the vegetative cells situated beside it. 



PLATE IV. 



The figures are magnified 50 times, with the exception of fig. 1, 

 hich is magnified 25 times, and figs. 7 and 8, 20 times. 



Pithophora sumatrana (v. Mart.) nob. 

 ig. 1. The lowest part of the thallus of a sterile specimen, with a rhizo'id con- 

 sisting of one cell, rh. 



Figs. 2 to 11. P. kewensis nob. 

 ig. 2. The lowest part of a fertile specimen with a rudimentary, extremely small 

 rhizo'id, rh. 



» 3. The lower part of a fertile specimen with a rudimentary rhizo'id, rh, Al- 

 though no parting wall exists between the rhizo'id and the cauloi'd of the 

 specimen, still an opening in the layer of chlorophyll of the basal cell indicates 

 the limit between those two parts. The spores sb and s are only seeming 

 twin spores, because they are formed by different mother cells, sb being a basal 

 spore of an upper cell, and s an apical spore of a lower cell. 



» 4. The lowest part of a sterile specimen with a rhizo'id, rh, of one cell and 

 of normal size. 



» 5. The lowest part of a sterile specimen with a very long rhizo'id of one cell. 



» 6. The lowest part of a fertile specimen with a rhizo'id of six cells. 



» 7. The lowest part of a fertile specimen with a rhizo'id of twelve cells and 



with an accessorial (rhizine) branch, ac, proceeding from the mother spore, sg 



of the plant. The uppermost among the cells of the rhizo'id shows at & a 



tendency to ramify. 

 » 8. The lowest part of a fertile specimen with a ramified rhizo'id, rh. 

 » 9. The lowest part of a fertile specimen with a sporiferous rhizo'id of two cells, 



and with a rudiment of an accessorial branch, ac, at the lower end of the 



basal cell of the cauloi'd. 

 » 10. The lowest part of a fertile specimen with a sporiferous rhizo'id, rh, of 



four cells and with an accessorial branch, ac, carrying spores and proceeding 



from the side of the mother spore, sg, of the plant. 

 » 11. The lowest part of a fertile specimen with a sporiferous rhizo'id of six 



cells. 



Figs. 12 to 18. P. Cleveana nob. 

 Fig. 12. The lowest part of a fertile specimen without a rhizo'id, but with a basal 

 spore, sgb, in the lowest cell of the cauloi'd. 



