Fig. 144 Delesseria sanguinea. A, plant. B, apex of thallus to show 

 cell arrangement ( x 258). C, first stage in formation of carpogonial 

 branch. 5ri= first group of sterile cells ( X408). D, later stage of 

 same, cp = carpogonial branch, 5c= support cell, 5fi= first, and 

 5f2= second group of sterile cells ( X408). E, mature carpogonial 

 branch. 5C= support cell. 5?^= first sterile branch, 5^2= second 

 sterile branch ( x 720). F, formation of antheridia in related genus, 

 Nitophyllum. G, transverse section of mature cystocarp in the 

 related genus Nitophyllum. H, tetraspores ( x 360). (A, F, G, after 

 Tilden; B-D, after Kylin; E, H, after Svedelius.) 



Ceramiaceae: Callithamnion (calli, beauty; thamnion, small bush). 

 Fig. 145 



This is a genus of very beautiful and delicate plants that possess 

 filamentous, radially branched fronds which are either mono- 

 siphonous or else corticated at the base, the cortication being 

 formed by rhizoidal filaments. The plants are commonly attached 

 by rhizoids and in many species the branchlets terminate in long 

 slender hairs. The cells of the vegetative thallus are usually multi- 

 nucleate, and in C. byssoideum there are protoplasmic pseudopodia 

 projecting internally from the ends of the cells, and although these 



254 



