On the PiTIIOPIiOKACEyE. 61 



or even four, if tbe wall marked /r, and not that marked ir", was the one first 

 formed in the germination. (Regarding this, see the paragraph on the germination). 

 As to the specimens that are represented pi. 5, figs. 1 and 2, it is impossible to 

 decide how much belongs to the rhizoid part, when it is not known with certainty 

 which part of the specimens has belonged to the original, germinated spore. If 

 the supposition were true, that the irregularly shaped organs marked tty are trans- 

 formations of this spore, only tbe processes rJi, pointing downwards, would belong 

 to the rhizoid part. Sometimes no transversal wall is formed in tbe spore at tbe 

 germination, and then the rhizoid either does not exist, or is only rudimentary. 

 The former is the case if the germinating spore has not at all been elongated 

 downwards (pi. 2, fig. 13 sgb; pi. 4, fig. 12 s(/b; pi. 5, fig. 3 s(j); tbe latter if it has 

 been somewhat elongated, but without a parting wall between the cauloïd and tlie 

 rbizoTd having been formed (pi. 4, figs. 13 and 14 rh; pi. 5, fig. 6 rh). PI. 4, fig. 

 14 shows a case, when tbe forming of a parting wall was commenced, but without 

 being completed. 



Sterile sjjecimens dift'er from tbe fertile by stronger ramification — 

 branches of the 2:d degree regularly existing — and by the branches being 

 placed two and two opposite to each other as often as singly. 



Measurements. This species is the smallest one in the whole genus. Its ve- 

 getative cells liave, it is true, a greater diameter than those of P. kewensis nob., 

 but the length of the individual cells as well as more especially of the whole plant 

 is considerably less. The greatest specimens that I have seen have been only 25 

 millimeter long, and specimens of a length of only 4-5 millimeter are not rare. 



Fertile specimens. Cauloïd part of the tballus. The cells of the 

 principal filament are on an average 70 fi thick; the smallest observed thickness 

 is GO /I and the greatest 90 f.i. Tbe cells in the branches of tbe l:st degree are 

 on an av. 55 ,« thick. Tbe limits of variation are 50 ;t and GO ,k. The branches 

 of the 2:d and 3:rd degree are not much less thick than those of the l:st; the 

 diameter of tbe cells is on an av. 50 i.i; tbe smallest diameter 45 fi and the gTeatest 

 55 |W. The length of the vegetative cells is less in this species than in other 

 species. Very short cells (1 74 -2 times as long as thick) occur not seldom in tbe 

 principal filament (pi. 4, fig. 13) as well as in the branches. Especially the cell 

 just beneath a terminal spore has this form (pi. 5, fig. 4). Very long cells (such 

 as in P. ktwcnsis nob.) do not exist. Only very seldom the cells are 20 times, 

 generally only 4 — 9 times as long as thick. The thickness of tbe terminal spores 

 is on an av. 93 /i and their length, on an av. 232 fi. The limits of variation are 

 indicated by ^^- ^^^ ^Ig '^o ^(_ -phe cask-shaped spores are on an av. 102 /.i thick, 

 and 21G f.i long. The limits of variation are indicated by 'I'sa. iso, mS, 2.» i"- '^'''^ 

 cylindric spores are on an av. 70 ,« thick and 1G4 ft long. Their limits of variation 



avp tl'- SO CS 70 90 „ 

 '^'^ 1. 120, 220, 114, 210 "• 



The cell of the rhizoid has a rather variable length. Most frequently it is 

 very short, l'/4 -4 times as long as thick (pi. 4, figs. 15 and IG), but sometimes it 

 is more developed as to length, as nincli as 10 times as long as thick (|)1. 4, 

 fig. 17). 



