230 ESSENTIALS OF BOTANY 
Under the class green alge are grouped plants of many 
degrees of complexity in their organization and mode 
of reproduction. Complex cells like that of Vaucheria 
are not uncommon, and other genera have cell 
colonies of net-like form or take on thread-like 
shapes, like @dogoniwm, or leaf-like or disk-like 
shapes, like the sea-lettuce or like Coleochete 
(Fig. 220). 
Highest in structure of all the green alge are 
the stoneworts (Figs. 158, 159). 
In green alge the chlorophyll is not disguised 
by the presence of other coloring material. Re- 
production is of many kinds, — often, as in 
Pleurococcus, wholly asexual, sometimes sexual, 
by the fusion of like gametes, and sometimes, 
as in @dogonium and Vaucheria, sexual by 
the fusion of unlike gametes. 
FUCUS, ONE OF THE BROWN ALGE 
295. Occurrence. — Fucus vesiculosus, 
or bladder wrack, one of the commonest 
of the so-called rockweeds, is found grow- 
Fic. 160. A Kelp .- : , 
(Laminin, one. DE usually on rocks between high- and 
of the Brown low-water marks, along the northern coasts 
eee coe of both hemispheres. It is often very 
; luxuriant, completely covering the sur~ 
face of the rocks to which it clings; and is extremely 
tough, resisting the most violent beating of the waves. It 
is easily recognized by the ribbon-like form (Fig. 161) with 
frequent branching and the numerous air-bladders which 
buoy it up in the water. 
OC 
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