ULOTRICHALES 



47 



is often reticulate or else forms an irregularly thickened band, and, 

 although there are no pyrenoids, the genus is characterized by an 

 abundance of starch in the threads. One to sixteen biflagellate 

 (quadriflagellate in one species) zoospores are formed in each 

 mother cell and are liberated by the thread fragmenting into H 



D I C 



Fig. 34. Microspora amoena. A, portion of thread. B, early cleavage in swarmer 

 formation. C, two young cells ( x 745). D, akinete formation ( x 550). E, forma- 

 tion of aplanospores. F, G, stages in germination of aplanospores. H, liberation 

 of zoospores. I, zoospores ( x 745). (C, D, I, after Meyer; rest after Fritsch.) 



pieces or else by gelatinization of the cell walls. There may perhaps 

 be biflagellate gametes, but fusion between swarmers has only been 

 seen in one species, whilst in another species gametes possessing 

 somewhat unequal flagellae have been recorded. This fact is 

 extremely interesting and, if true, would make a reorientation of 

 ideas about this genus essential. Microspora exhibits considerable 

 variation, particularly in a xanthophycean direction, and in many 



