192 PHYLUM IV. SIPHONOPHYCEAE 



sexual organs, and are to be regarded as mere vestiges of 

 the fully developed antherids and oogones of the Green 

 Felts. • They are sexual organs on the road to extinction. 

 In the Insect Fungi the sexual organs are still more de- 

 generated and vestigial in structure. 



288. The commonest example of the Higher Tube 

 Algae is the little Bladder Alga (Botrydium), found on 



„^ moist ground. It is a globular coenocyte 



"" a millimeter or two in diameter, with a 



branching root below. When in good 

 vegetative condition it is bright green, but 

 later it may be dull red. It is known to 

 _ propagate by uniciliated zoospores, and 



Botrydium and thick walled chlamydospores. Its genera- 



Protosipnon. _ ./ jr o 



tion was long supposed to be by the union 

 of biciliated isogametes, but these are now thought to 

 belong to Protosiphon, a similar plant with an unbranched 

 root. 



289. In the shallow waters of the ocean there are 

 larger Bladder Algae (Valonia) that when young are 

 single globose or club-shaped coenocytes, firmly rooted 

 below. They may reach several centimeters in height, 

 and ultimately become more or less divided 

 into segments. Their propagation and 

 generation appear to be much like that 

 of the little Bladder Algae. 



290. The Sea Ferns (Bryopsis) are erect, 

 slender, cylindrical, single coenocytes, rooted 

 below, and pinnately branched above, and fiq. ss.— Bry- 

 look like httle trees, or fern-leaves. They Sbuiarir.'* '^°'" 

 generate by biciliated heterogametes. They 



occur along the shores of the warmer oceans. 



291. The pretty Sea Umbrellas (Acetabularia) are 

 also erect, slender, cylindrical, single coenocytes, rooted 



