THE ALG^E 



113 



chromatophore forms a more or less interrupted continuous thin 

 plate, but may some- 

 times be replaced by A 

 numerous separate chlo- 

 rophyll bodies. 



The other fresh-water 

 genus, Vaucheria (Figs. 

 88, 89), consists of elon- 

 gated tubular filaments, 

 occasionally attached by 

 colorless roots, but quite 

 as often floating free 

 in the water. The fila- 

 ments branch irregu- 

 larly, and may become 

 constricted at the base, 

 and separated as new in- 

 dividuals. The chroma- 

 tophores are small oval 

 plates, with their long 

 axes coinciding with 

 that of the filament. 

 Drops of oil are often 

 seen in the protoplasm, 

 probably the product of the photosynthesis in the chromatophores. 



Marine Siphoneae. The 

 most specialized of the 

 Siphonese are marine. 

 The beautiful feathery 

 Bryopsis (Fig. 85, A), 

 and the spongy-looking 

 Codium, are the best- 



sp HHI - /'// 1 known forms from the 

 temperate seas. In the 

 tropics, especially about 

 coral reefs, the Siphoneae 

 reach their greatest de- 

 velopment. Many of 

 these forms, like Hali- 

 meda (Fig. 86), Penicil- 

 lus, Acetabularia, are 

 heavily incrusted with 

 FIG. 85. A, Bryopsis plumosa (x 2). B, Codium carbonate of lime, and 

 tomentosum, end of a filament with sporangium, i imrtortant nart 



sp. (X50). C, gamete (?) (X300). (C, after P la ^ an 

 THURET.) in reef-building. 



FIG. 84. A, Botrydium yranulosum (X 10). B, a 

 zoospore (X 540). C, D, germinating zoospores 

 ( X 550) . E, part of root containing aplanospores 

 (X 40). F, conjugating gametes (X 540). G, 

 zygote (X 540). (B, F, G, after STKASBURGER.) 



B 



