210 



Dansk Botanisk Arkiv, Bd. 3. Nr. 1. 



hand, the cells in this part of the stem are mostly short ones, 

 often reaching only a length of ahout 100//. From this jDlace 

 the cells gradually taper upwards, becoming at the same time 

 longer. In the middle of a plant the cells are about 450 /^ long 

 and 230 ß broad ; they are nearly cylindrical, yet somewhat swol- 



i 



Fig. 195. Mesothamnion caribaeum nov. spec, a, part of tetrasporic plant. 

 h, part of a female plant, (o, about 40:1; b, about 50:1). 



len at the base, tapering upwards and again a little thicker at 

 their upper end. 



Near the summit of a branch in active growth the cells in the 

 main filaments are almost quadratic, about 15// broad. In some 

 plants a main stem can be followed through the whole length of 



