432 



From this growing zone the cells gradually increase in length 

 towards both ends. The filaments are about 35 t a thick and the 

 cells reach a length of up to 90 fj.. The peripheral walls are about 

 2 fj. thick. 



In some of the filaments rhizoid-like short branchlets were 

 found (408 a). These seem to be able to grow out from all vegeta- 

 tive cells; in one filament, for instance, they were growing out 

 from both ends of the filament. Another filament was much curved 

 in the one end and from nearly all the cells here short branchlets 

 were issued from the convex side of the filament. According to 



Fig. 409. Pylaiella fulvescens (Schousb.) Bornet. 



- a, b, cells with chloroplasts and nuclei, c, parts of a fertile filament. 



(About 350:1.) 



SAUVAGEAU this takes place in the upper ends of the erect fila- 

 ments, these by means of these branchlets, crampons becoming 

 often fixed also in the upper end. The branchlets may attain 

 to a considerable length; they have more or less sinuate walls. 

 They are about 16 ^ thick, their cells being about four times 

 longer than broad. 



The cells contain a beautiful and very characteristic chrom- 

 atophore, closely reminding of the one in Zygnema (Figs. 408 a, 

 409). The chromatophore is stellate; from a dense centre long, 

 thin prolongations protrude in all directions towards the wall 

 of the cells, here often being broadened out to small roundish 

 or oval discs lying closely against the wall. Two stars of chro- 

 matophore are present in each cell; in the longer cells the distance 



