THE VARIOUS GROUPS OF PLANTS 



37 



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Fig. S. — Some Brown Algae (Phaeophyceae). A, Ectocarpiis, a filamentous type 



( X 45); B, Dictyota (x h); C, Fucus (x i); D, Agarum (x iV); E, Chorda 



X i); F, .4/anVz (x -0^;); G, Ulopteryx (x -iN,-); H, Sargassum ( < J). 



resiculosiis). Types of Brown Algae living between tide-marks, as 

 many do, are usually whippy and tough enough to remain uninjured 

 by the waves. In some of the giant Kelps the ' fronds ' have a 

 relatively complex internal structure and may be around 200 feet 

 in length. (Reports of much greater lengths do not appear to have 

 been authentic.) 



The Brown Algae obtain their food for body-building, growth, 

 and energy by means of photosvnthesis, the raw materials for this, 

 carbon dioxide and water, being absorbed over the entire surface, 

 as are also the needed salts, etc., in solution. Reproduction is 

 effected asexually by fragmentation of the thallus or by liberation 

 of motile spores (zoospores), or, sexually, by the fusion either of 

 two similar motile gametes or of dissimilar gametes. When there 

 are dissimilar gametes one, the male, is motile and small while the 

 other, the female, is non-motile and relatively large. Thus sexuality 



