223 



Higher up in the stem 

 the cells grow evenly, thin- 

 ner in the middle of the 

 plant about 85 p thick, 

 becoming at the same time 

 more thin-walled and long- 

 er (4 5 times as long as 

 broad), decreasing in thick- 

 ness evenly towards the 

 apex, the ultimate cells 

 being only 8 11 p. thick. 

 These often, but not always, 

 end in a thin hair (Figs. 

 210 Z>, 2114). Breadth of 

 the hair about 3^. 



The plant is not corti- 

 cated. It is richly rami- 

 fied on all sides, in the 

 uppermost part subdicho- 

 tomously. 



Both the younger and 

 older cells have only a single nucleus (Fig. 210 B, F), in accor- 

 dance with the description of ScHMixz 1 ). The parietal chromato- 



Fig. 210. Seirospora occidentalis B0rgs. 

 A, base of a plant (25 : 1). B and C, 

 branches with tetraspores (60 : 1). D, branch 

 with antheridia (60 : 1). E, antheridia 

 (150 : 1). F, cells with chromatophores and 

 nucleus (150 : 1). 



Fig. 211. Seirospora occidentalis B0rgs. A, branch with nearly ripe cysto- 

 carp. B, D, young cystocarps (150:1). C, procarp (150:1). 



, FR., Die Gattung Microthamnion J. Ag. (= Seirospora Harv.) 

 . d. deutschen bot. Gesellsch., Bd. XI, 1893, p. 273. 



