98 



1 mm, with the hairs the diameter is more than 2 mm. The hairs 

 are evenly distributed over the whole thallus giving it a felted 

 appearance. The colour is rather variable, in some specimens red- 

 brown in others greyish olive-green with a more or less reddish tinge. 



As to the anatomical structure 

 the medullary tissue consists of 

 rather thick-walled filaments woven 

 together. The filaments are of very 

 variable size most often about 

 11 13 // broad but some occur 

 which reach more than the double 

 thickness; the diameter of the 

 whole tissue reaches a width of 

 about 650 <JL. 



Towards the periphery these 

 filaments bare the polygonal sup- 

 porting cells commonly found in 

 this group (compare Fig. 103). 

 These are mostly 4-gonal and about 

 40 50 [i. broad. The assimilating 

 filaments arising from these cells 

 are of two different kinds, some short 

 and others long. In the older parts 

 of the thallus the long assimilating 

 filaments especially occur while the 

 shorter ones usually are very rare, 

 in the young thallus the shorter 

 assimilating filaments are quite as 

 common as the longer ones. The 

 short filaments consist of three, 

 sometimes only of tw r o cells (Fig. 

 103 b) and these cells decrease ra- 

 pidly in size upwards. The low r est 

 cells are large up to 70 fj. or even 

 longer and about 45 jj. broad, the 

 uppermost ones are only about 28 

 30 // broad. 



The basal cells in the long assimilating filaments are of about 

 the same shape and size as those in the short filaments. Above 

 the low r est largest one, a smaller oval cell follows and sometimes 

 the following cell is yet somewhat swollen in the middle while 

 the rest of the cells in the filament are cylindrical, mostly about 



Fig. 103. Galaxaura lapidescens 

 (Sol.) Lamx. a, long assimilating 

 filaments, b, short assimilating 

 filament and basal part of a long 

 one issued from the same sup- 

 porting cell. (About 150 : 1). 



