35 



Griff ithsia niay be anchorec'. to the sulDstratuin either 

 "by a special attaching disk, or more usually by a tangled 

 mass of rhizoids. An e-ttaching disk has been noted in 

 plants growing on Zoste ra and smooth rocks, but v/hen, as 

 is often the case. Griff ith sia as attached to other algae 

 of cylindrical habit, the disk is replaced by a ta,ngled 

 mass of rhizoids, which are short, thick-wa-lled, and filled 

 v/ith starch. Inspection of a number of specimens sliov/s all 

 stages of transition from a mass of rhizoids to a. well de- 

 veloped att&ching disk. The disk xna,y be said to be formed 

 of rhizoids in contact laterally. The development of the 

 attaching organ is described on page Q>Q • 



The attaching disk when present is formed of a single 

 layer of heavy-walled cells, bright pirJc in color owing to 

 the presence of numerous cliromatophores, densely filled 

 with protopla,sm, and packed with laj?ge starch grains (figs. 

 55,56). ?rom it new shoots may arise. 



Judging from analogy v/ith other forms (see OLTKAOTS, 

 •04, p, 64B, a,nd »05, p. 212) v/e may assume tiiat the plant 

 winters over by means of the atta.ching disks or the mass 

 of rhizoids at its base. In the spring these give rise to 

 the plants which reach perfection in tlie summer. Tlie ev- 

 idence for tiiis is rather negative. 1, The first plants 



