58 



A TEXTBOOK OF THEORETICAL BOTANY 



Reproduction 



Reproduction may be sexual or asexual (Fig. 32). In asexual repro- 

 duction the active cell comes to rest, the flagella are withdrawn, and the con- 



Fig. 32. — Chlaniydomonas. Stages in reproduction. A to C, Stages in the 

 division of the cell into zoospores. D, Mature zoospore. E and F, 

 Stages in the division of the cell into gametes. G, Mature gamete, 

 H to L, Stages in the fusion of the gametes. {After Pascher.) 



tents of the cell divide up into four, eight or sixteen parts, which become 



zoospores. A zoospore is a motile cell, very 

 similar to the parent cell but smaller. It may 

 either become active and swim away or may re- 

 main enclosed by the parent wall and grow and 

 divide again, so that under some conditions a 

 large number of zoospores, usually without flag- 

 ella, may be found clustered together inside an 

 envelope of mucilage. This aggregation of cells 

 is spoken of as the palmella stage, from its re- 

 semblance to another Alga of that name. The 



^'''' Ce\lTn'^SSl'~: ^^"' ^^^^ly ^^^e^t, however, to the motile condition 

 duction, Palmella stage. (Fig- 33)- 



