47 



p. 54 ; Cladophora (Spongomorpha) arcta ;-. hystrix, K. Rosenv. 

 Grl. Havalg. p. 907. 



The Greenlandic specimens are 4 — 15 cm. high and the 

 thickness of the upper branches is varying from 200 — 500 ^. 

 The sporangia mostly occur singly or two or three together, 

 but up to 6 sporangia in a contin- 

 uous row are not rare. Neither 

 spinous, nor hooked or incurved 

 branches are met with. The tufts 

 are loose and almost not entangled 

 [in f. typica] or somewhat entangled 

 at the base As in other species of 

 Acrosiphonia the main branches are 

 much narrower below than above. 

 As in A. incurva the main axis of 

 young plants terminates in an axile 

 rhizoid, which afterwards dies off; 

 sometimes it is replaced by a new 

 axile rhizoid. but in older plants 

 the lower end of the main axis 

 usually dies off. Lateral rhizoids are 

 rare in the typical form, but rather 

 frequent in the f. Uttoralis; they 

 never occur in such quantities as in 

 A. incurva. The lowest rhizoids are 

 often unilaterally placed while the 

 upper rhizoids are opposite, alternate 

 or scattered. The basal cell of the 



Fig. 6. Acrosiphonia hystrix 



(Strömf.). 

 a the basal portion of a young 

 specimen showing an axile 

 rhizoid and mostly secund 



lateral rhizoids. 47 : 1. 

 b the basal portion of an older 

 plant showing an axile rhizoid 

 produced by renewed growth 

 dying off, besides both opposite 

 and scattered lateral rhizoids. 

 47: t. 



rhizoids is usually considerably en- 

 larged, it is lobed or irregularly branched and sometimes it 

 emits stolons from which erect filaments arise. Renewed growth 

 of injured rhizoids and branches as described in A. incurva 

 (p. 43 — 44) also occurs in this species. The young apices of the 

 branches produced in this manner sometimes resemble flagelliform 



