SECT. I 



CRYPTOGAMS 



365 



Fio. 287. — Vanchcria sessilis. 

 which it has escaped. 



A, Young sporangium. S, Zoosjjore with the 

 C, A portion of the peripheral zone of a zoospore. 



sporangium from 

 D, A young jjlant 



with rhizoids developed from a zoospore. 

 Algae. C, aftctr Strasburger.) 







^^sM 



Fio. 2SS. — Vmu-heria fessilis. Portion of a filament 

 with an oogonium, ; antheridium, « ; rh, ehro- 

 matophores ; n, cell nuclei ; ol, oil globules. 

 (X 240.) 



(.1, I;, after Gotz ; D, after Sachs ; from Oltmanns' 



short lateral branches, and become 

 separated by means of sejjta from the 

 rest of the thallus (Fig. 288, o, a). At 

 first, according to Oltmanns and 

 Heidinger, the rudiment of an oogon- 

 ium contains numerous nuclei, of which 

 all but one, the nucleus of the future 

 egg-cell, retreat again into the main 

 filament before the formation of the 

 septum. In its mature condition the 

 oogonium has on one side a beak-like 

 projection containing only colourless 

 protoplasm. The oogonium opens at 

 this place, the oosphei'e rounding itself 

 off. The antheridia, which are also 



-Ti 



-cfv 



multinuclear, are more or less coiled («), and open at the tip to set free their mucil- 



