204 Fri f seil . Stiulifs on ( Vannphycoap. 



ceal)l»' tli;it all tlu- iiulividual pairs of colls. Avliidi arc tlms each 

 cnveloped l)y a common cell-sheatli , lio in oiic dircction: this 

 sliows that divi.^ion is prevalent in tliis dii'oction. Tlic mucila«,^' 

 invcstmont of tlio wliole colony is well-markcd in stained material 

 and in-oji'fts only veiy sliglitly beyond tlie general contour of 

 the aggregato of cells. 



(d) O.sciHaria and Lyughya. In the genus OscWaria^ wliicli 

 is of considerablo intorest from tlie point of view of tlie presont 

 paper, it was found convenient to examine a species witli faiily 

 broad filaments, as sucli tend to make tlie recognition of details 

 of structm^e in the Investment rather more easy; the foUowing 

 observations therefore in the main refer to OscÜlar/a Fröhl'ich'i'i. 

 The cells which constitute the filaments of this species are flat, 

 generally several times broad er than tliey are long (cf. fig. 11) 

 and the colomdess septum between adjacent cells is only of very 

 slight widtli; when the cell-contents are very granulär it is almost 

 impossible to recognise the delimitations of the individual proto- 

 plasts. as the graniües tend to aggregate about the region of 

 the septa. The whole row of cells or filament is here enclosed 

 in one general shoath, which is however qnite evidently merely 

 due to the coherence of the individual cell-sheaths of an A}ia- 

 haena or No.sfor. In correspondence with the slighter develop- 

 ment of the transverse septa the sheath is not split dnring 

 division, but remains as one continuons wliole round the entire 

 row of cells. However the sheath still shows its composite 

 origin. in that it is sliglitly constricted at each point of Separa- 

 tion of two contiguous cells (fig. 11, es.); these contrictions 

 run transversely riglit round the filament and give rise to a 

 rough stratification in surface view. The colourless inner Invest- 

 ment of each cell (fig. 11, i. i.) is rather better seen laterally 

 (i. e. on the inner side of the sheath) and is generally very 

 readüy visible at the apex of the filaments. 



In the year 1897 two papers, dealing with the structure of 

 the cell-membrane and the movements of OsciUar'm were publis- 

 hed (Correns 97. Kolkwitz 97), but the subject-matter con- 

 tains very little bearing on the present paper. The outer walls 

 (i. e. the coherent cell-sheath) show a reticulate structure ac- 

 cording to Correns, when treated in a certain way, and in 

 connection with this, the foUowing statement of this observer 

 is of some interest here: „Bei weit geöffneter Irisblende sieht 

 man ein rotes Netz auf farblosem Grunde, schmälere oder 

 breitere farblose Streifen laufen den Ansatzlinien der Scheide- 

 wände entlang'- (p. 139). That is to say the parts of the 

 coherent ceU-sheath, which lie opposite the lines of Separation 

 of the protoplast (the region, where the cell-sheath splits on 

 division in AnahaprwA)^ show a different structure to that of 

 the remainder of the sheath. 



Treated with Vesuvin the cell-sheath of an OseiUaria be- 

 comes very prominent and the inner Investment also seems to 

 take on a faint brown colouration, although this appearance 



