372 



b a 



Fig. 16. Acrosiphonia flabelliforniis. 



a tlie uppermost part of a branch with branch- 

 lets showing the resumed divisions (10 : 1), 

 b the lower part of a main branch with 

 rhizoids (15 : 1). 



different size . but never as 

 large as in A. hystrix. The 

 pyrenoids are numerous and 

 rather dense. Regarding the 

 structure of the chromatophore 

 this species somewhat resem- 

 bles A. setacea Kjellm. (Acro- 

 siphonia Tab. II, fig. 12). Cells 

 containing large quantities of 

 starch, both as starch envel- 

 opes surrounding the pyrenoids, 

 and as numerous free grains, 

 are frequent in the older parts 

 of the branches and occur 

 largely, sometimes up to 50 

 or more in continuous rows. 

 The branching of the upper 

 part of the frond is for the 

 most part repeatedly secund 

 and corymbous, and the bran- 

 ches of different orders, per- 

 taining to the same main branch, lie for the most part in one and the 

 same plane. The upper part of a main branch with its different branches 

 is thus of a flabellate shape. 



The upper part of the branches is frequently considerably narrower 



and evidently much younger 

 than the lower part and 

 produced by resumed di- 

 vision of the old apical 

 cell as shov.'n in my fig- 

 ures (fig. 16 a, fig. 17 6— (^). 

 The resumed division of 

 the apical cell occurs, I 

 think, after a resting-period, 

 as in species of Clado- 

 phora (cfr. Rosenv., Clado- 

 phora and Ghsetomorpha 

 p. 19 — 20). Rhiziues are 

 abundantly occurring, also 

 from the upper branches, 

 and frequently produced 

 by resumed division of 



a bed e 



Fig. 1 7. Acrosiphonia ftabelliformis. 



a the uppermost part of a main branch showing 



the shape of the apical cell, b, c, d show the 



resumed divisions (comp. the text) and e the sheath 



enclosing the rhizoids (comp. the text). 



a, b, c, d (15 : 1), e (126 : 1). 



