8 



plants. Tlie root is a flat and not very thick plate of 

 tissue, wliich adlieres very closely to the rocky substratum. 

 No food material apparently is absorbed from the latter. 

 There is no reason, however, why the exposed portion of 

 the attachment disc should not extract some food material 

 from the surrounding- sea water. It is coloured a faint 

 red, and it may therefore assist in the process of assimila- 

 tion, but only to a limited extent. It is, however, an 

 important organ for the storage of food material. It 

 grows in circumference along its margin, covering every- 

 thing that may happen to be attached to the rock and 

 extending into any small holes and crevices in the latter, 

 thereby acquiring a very irregular shape (PI. III., fig. 9). 

 By this means the whole plant gets very firmly attached to 

 the sea l)ottom (see PL I.) 



From the fiat root disc arise the numerous upright 

 SHOOTS. These are at first undivided and more or less 

 cylindrical in transverse section. But they soon become 

 flattened, and when they have attained a height of 1*5" 

 (•'} cm.), tliey are always divided. The full grown shoot 

 is as a general rule more or less flattened throughout. Its 

 lowest end, however, just where it joins the root organ, 

 may be cylindrical, but it soon becomes flattened, even if 

 only slightly. With its hrst division the shoot becomes 

 very much flattened and very thin. The branching of 

 the leafy portion of the shoot is throughout a very regular 

 kind of forking. No midrib is formed, the texture of the 

 shoot being fairly uniform and almost leathery 

 throughout. 



The shape of the separate shoots is very simple and very 

 uniform amongst the individuals even of very different 

 localities — be they broad or narrow forms. A fairly long 

 and undivided stalk can be distinguished from the much 

 divided frond. In the taller plants, found chiefly at low 



