18 HENRIK PRINTZ [1920 



the cells get a nearly ovoid shapc. The chromatophore is a pallid 

 green, parietal slab, and does not line mare than one half ol" the 

 menibrane. Because of Ihis, tlic polos of the oeills are commonly 

 colourless, or the cliromjatophore is lateral, and fills one half of the 

 cell only, by which the other half gets colourless. In the 

 cells are often lo be found small refractive grains. A pyrenoidl is 

 wantmg. 



In the ciourse of time have been referred to Stichococciis bacil- 

 laris a great nmnber of various forms, many of which are certainly 

 quite different species. If tlie drawings given by the diifferent 

 authors are compared, great disiagreiements will be observed both 

 in the shape, size, and imier structure of the cells. Fmther, some 

 authors record the species to have a pyrenoid, others a pyrenoid to 

 be wanting. In my opinion, however, the presence or absence of a 

 pyrenoid is no particularly important systcmatic character, as 

 among algae of undoubtedly near relationship, one species may 

 have, the other one may be destitute of a pyrenoid. To malve a 

 distinction between two genera solely on such a character as the 

 absence or presence of pyrenoids, as e. g. to establish the genus 

 Palmellococciis including the species of Chlorella, wanting the pyre- 

 noid, therefore may not be quite well-founded in systematical re- 

 spects. Within one and the same species, however, this is a constant 

 character. It is also dubious what systematical importance should 

 be assigned to a character, as wdiether the cells of Stichococcus 

 coher in rows or disintegrate innnediately after the cell-diivisions. 

 This character, at any rate to a certain extent, may be dependent on 

 the nature of the habitat, especially perhaps on the conditions of 

 humidity, and is in some degree, at least, not without influence on 

 the shape of the cell-ends. The specimens found b}'^ me from South 

 Africa, agree perfectly with the description and figures of the species 

 St. minor, lig. 66, given by Heering in Pascher's Algenflora; 

 especially characteristic are the oblique or somewhat curved cells, 

 with the broadly rounded ends. 



Pleurastrum constipatum lov. spec. [PI. III, Fig. 124—155]. 



Thallo ex stnubus cellnlarum parencijmaticanim irregulariter 

 formatis, 1-plures celliilanim series crassis, numero variablliiim 

 usque ad amplius centum cellularum constante. CelluUs singiiUs 

 et magnitudine et formå multum variis. Cellidis breul post 

 divisionem ad 3,5 j,i parvis, adultis et majoribus ante diuisio- 

 nem usque ad 9 u magnis. CelluUs polygoneis, fere isodia- 

 metricis parielibus pro ratione crasis instructis. In cellulis nucleis 

 singulis. Chromatophoro campanulato totum parietem interiorem 

 obtegente, nullas partes vacuas achroas relinquente. Pyrenoidibus 

 nullis. Acinetis propagationis cellulis singulis rotundatis et dis- 

 solutis ortis. Zoosporis parvis, 1,5—1,8 ju longis in sporangiis, neque 



