— 265 — 



From the creeping filaments grows the erect part of the thal- 

 lus, the stalk crowned with the frond. From its earliest stage of 

 development the stalk consists of a single, nearly cylindric cell. 

 At its base, at least in more mature specimens, we find a few, 

 6—8 annular corrugations though not very deep (fig. 13). When 

 the stalk has reached nearly the normal height of the plant it 

 divides into a number of cells. The forming of these cells is said 

 by J. Agardh (I.e. 

 p, 108), who founds 

 his description on 

 that of Harvey x ), 

 to be due to an 

 apical cell, but this 

 is not right, judging 

 from what I have 

 found in my mate- 

 rial. I have obser- 

 ved the cell division 

 in the frond of a 

 young plant, of 

 which fig. 14 c shows 

 the uppermost half- 

 part. We see here 

 that the side bran- 

 ches and the apical 

 cell first grow out 

 to a considerable 

 length and then the 

 cell contents in each 

 branch are divided 

 simultaneously into 

 a number of smaller 

 parts of nearly the 



Fig. 14. Struvea elegans n. sp. 



a. b. c. tops of young stalks shoving development of the frond and 

 c the cell division also, the uppermost branches in this figure and 

 the topcell are yet undivided, then branches occur where the cell 

 contents are aggregated in clumps and lower down again the cell- 

 division has been completed and in the lowest pair of branches 

 side branches begin to grow out. cl. part of older thallus. e- f. 

 hapteræ. g. chromatophores. (a.b. about 3:1, c. 6:1, d. 10:1, 

 e. /.. 70:1, g. 300:1). 



same size, with exception of the apical cell in each branch, which 

 is longer. Each of these smaller part's becomes surrounded by a 

 membrane. The figure shows that the branches nearest the top 

 are yet undivided. Somewhat lower down, where the division of 



x ) Compare also Murray and Boodle, 1. c; Oltmanns, Morphologie, p. 267; Wille 

 in Engler und Prantl, Natürl. Pflanzenfam., Chlorophyceæ, Nachtr., p. 113. 



