F. Børgesen: List of species. 



425 



of the specimens the original basal rhizoids were present, the 

 plants being fixed by means of them to the rocks. Most probably 

 the end-rhizoid had been cut off during the gathering in the spe- 

 cimens in which it was absent. 



The basal rhizoid (comp. Fig. 406 and 407) is below broad- 

 ened out to a small disc with irregular coralliform outline, and 

 the base on the whole becomes gradually 

 strengthened by means of throughgrowing 

 of the lowermost cells in the filament 

 down into the basal cell in a way similar 

 to that known so well in Chætomorpha. 

 This throughgrowing can take place in 

 three to four of the basal cells, the lowermost 

 cell in this way becoming rather long. 



As already mentioned the original 

 basal rhizoid in Rhizoclonium is very rarely 

 found. Regarding Rhizoclonium Kerneri 

 Stockm. Wille in "Studien über Chloro- 

 phyceen", VII, p. 41 writes, as follows, 

 concerning the basal rhizoid: »Beim Kei- 

 men der Zoosporen bildet sich ein basales 

 Endrhizoid (Taf. IV, Fig. 166—68); aber 

 da sich die Fäden durch intercalare Teilungen und zufällige 

 Zerreissungen sehr stark vermehren, so findet man Fäden 

 mit Endrhizoid sehr selten. Inwiefern die Fäden ursprüng- 

 lich festsitzen, kann ich nicht mit Sicherheit ausmachen, viel- 

 leicht darf die eigentümliche starke Verdickung an dem abgebil- 

 deten Rhizoid (Taf. IV, Fig. 168) als eine abnorme Entwickelung 

 gedeutet werden, indem sie keine Gelegenheit gehabt hatte sich 

 zu befestigen, da dieses Exemplar nur loose zwichen den übrigen 

 Fäden hing«. Regarding the presence of basal rhizoids in my 

 specimens no doubt is possible. They were vigorously developed 

 and present in all the specimens. As the plants have no other rhi- 

 zoids to fix themselves with they would immediately have been 

 washed away by the waves, if they had not been fixed by the 

 basal rhizoids. 



The filaments increase by means of intercalary divisions 

 of the cells, these being divided when they have reached a cer- 

 tain length. 



Fig. 407. Rhizoclonium 

 Kerneri Stockm. Two 

 forms with the original 

 bases, [a — e, about 260:1; 

 f. about 500:1.) 



