Siphon Algae 



121 



is known as conjugation, whence the group name) and 

 the development of a protective wall about the result- 

 ing reproductive body. This rests for a time like a seed, 

 and on germinating, produces a new filament by the 

 ordinary process of cell division. These filamentous 

 forms share this reproductive process with the desmids, 

 and despite the differences in external aspect it is a 

 strong bond of affinity between the two groups. 



The siphon algcE — This 

 peculiar group of green 

 algse contains a few forms 

 of little economic con- 

 sequence but of great 

 botanical interest. The 

 plant body grows out in 

 long irregularly branch- 

 ing filaments which, 

 though containing many 

 nuclei, lack cross par- 

 titions. The filaments 

 thus resemble long open 

 tubes, whence the name 

 siphon algse. There are two common genera Vau- 

 cheria and Botryditmi (fig. 42). Both are mud-lov- 

 ing, and are found partly out of the water about as 

 often as wholly immersed. Vaucheria develops long, 

 crooked, extensively interlaced filaments which occur in 

 dense mats that have suggested the name "green felt." 

 These felted masses are found floating in ponds, or 

 lying on wet soil wherever there is light and a con- 

 stantly moist atmosphere (as, for example, in green- 

 houses, where commonly found on the soil in pots). 

 Botrydium is very different and much smaller. It has 

 an oval body with root-like branches growing out from 

 the lower end to penetrate the mud. It grows on the 

 bottom in shoal waters, and remains exposed on the 



Fig. 42. Two siphon algae. 



A, Botrydium: B, a small fruiting portion of a 

 filament of Vaucheria.; ov, ovary; sp, spermary. 



