426 Dansk Botanisk Arkiv, Bd. 3. Nr. 1. 



The cells contain a very irregularly shaped chromatophore 

 of a reticular spongy appearance with smaller and larger openings. 

 Often it fdls up the whole lumen of the cell so densely that it is 

 impossible to see its shape. In the chromatophores a large number 

 of pyrenoids are present, distributed regularly in the cells. The 

 cells contain, according to their size, one to four nuclei. 



With Iodine and Chlor-Zinc-Iodine the chromatophores 

 are coloured black showing that much starch is present. With 

 the last mentioned chemical the walls of the cells do not show 

 the cellulose reaction, the wall, just as when treated with Iodine 

 alone, getting a light yellow tinge. 



In the upper end of the filaments the cells gradually are 

 transformed into zoosporangia; the zoospores escape through 

 an opening in the wall of the cells. In accordance with the descrip- 

 tion of Wille this opening occurs a little above or below the 

 middle of the cell, and the place, where it will come into existence, 

 is beforehand marked by an outgrowth of the wall. 



To point out any differences between these affixed forms 

 of Rhizoclonium, as are described above, and Chætomorpha seems 

 nearly impossible, and Stockmayer, too, has already mentioned 

 this difficulty in his monograph of the genus Rhizodonium, and 

 that in spite of the fact that he did not know such forms fixed 

 by the original end-rhizoid. Should I try to mention some differ- 

 ences between such forms of Rhizoclonium, as are mentioned 

 above, and Chætomorpha I think the most essential differences 

 are, besides the lesser dimension of the filaments, that the fila- 

 ments of Rhizoclonium are mostly quite cylindrical, in Chæto- 

 morpha mostly moniliform, that the cells of Rhizoclonium are 

 mostly proportionally longer and have thicker walls than those 

 of Chætomorpha, that now and then in the filaments of Rhizo- 

 clonium a thickening of the wall is found round above the cross- 

 wall between the cells (comp. Fig. 406 h) while in Chætomorpha 

 the filaments are narrowed here. Characteristic of Rhizoclonium 

 is also a kneehke bending (comp. Stockmayer, fig. 4, pag. 576) 

 found now and then in the filaments. On the whole the appear- 

 ance of a Rhizoclonium filament is rather like a Conferva, but 

 the structure of the wall is quite different. Regarding the chrom- 

 atophore its reticular structure is more easily seen in Chætomorpha 

 than in Rhizoclonium in which the dense clumsy-spongy structure 

 mostly makes it very indistinct. 



