50 



PLANT MORPHOLOGY 



B 



D 



Fig. 37. Several desmids, showing variety of form. A, end view and B, front view of 

 Staurastrum; C, Docidium; D. Cosmarium, E, Micrasterias; C, X250; others, X400. 



G^: 



mm 



Fig. 38. Single cells of Moiigeotia, showing the plate-like chloroplast as seen in side (A) and 

 face (B) views, X500; C, conjugating filaments, with three zygotes formed in the conjugat- 

 ing tubes. (C, after Wittrock.) 



ing an entire vegetative protoplast, are nonciliated. The zygote becomes 

 thick-walled and, after a period of rest, its protoplast escapes and divides 

 generally into two daughter protoplasts, each of which becomes a new 

 individual. As a result of two successive divisions of the zygote nucleus, 

 during which the reduction of chromosomes occurs, each daughter proto- 



