C(EL0BLA8TE^. 



251 



other objects, by root-like processes {w, Fig. 168). The 

 protoplasmic contents of the tubes, which are destitute of a 

 nucleus, consist of a thick green layer upon the inner sur- 

 face of the wall, leaving the centre of the tubes open for the 

 more watery portions. 



335.— The asexual reproduction of Vaucheria presents 

 some considerable variations ; it consists essentially of a 

 spontaneous separation of a portion of the protoplasm of the 

 parent plant. In some species this takes place by the sepa- 



f\Q- 



Pig. 168.— Vmiefieria sessiUs. A, end of a branch, with escape of a zoospore, sp. B, 

 zoospore in its ret-ting stage, after the disappearance of its cilia. C, the same, germi- 

 Dating. D^ the same, further advanced. E, much later stage of germination ; sp, the 

 EooBpore: w the root-lils« processes irhizoids). F, fertile plant; og, og, oogonia fer- 

 tilized ; h, an old antheridium. X 30 —After Sachs. 



ration of swollen lateral branches, which then send out fila- 

 ments ; in other species the protoplasm in the swollen lateral 

 branch becomes separated from that in the general cavity of 

 the plant by a septum, and it afterward condenses into a 

 rounded mass and acquires a wall of its own ; it is set free 

 by the decomposition of the old surrounding wall, and it 

 germinates by sending out one or two tubes, which grow 



