V EG ETA TIVE REP ROD UCTION. 



213 



When zoospores possess chlorophyll -bodies, as they fre- 

 quently do, they are aggregated at 

 the larger end, leaving the pointed 

 end to which the cilia are attached 

 colorless. Zoospores are formed 

 either in a general body-cell, not 

 visibly different from the other 

 body-cells, or in a cell specialized 

 in form and structure. In either 

 case the cell in which they are pro- 

 duced is called a zoosporangium. 

 The entire contents of the zoospo- 

 rangium may form a single zoospore, 

 or it may divide into several or 

 many. In the latter case the nu- 

 cleus divides into two or more, each 

 of which gathers about itself a por- 

 tion of the protoplasm. The zoo- 

 spores are set free by the rupture of 

 the wall of the sporangium or by 

 the solution of a portion of the wall 

 (fig. 208). They may begin to 

 move before the rupture of the wall, 

 in accomplishing which their activ- 

 ity may materially assist. They 



then WOrk their Way OUt and Swim Fir - 208.— Development and escape 



of zoospores of an aquatic fungus 



freely in the Water. After a time (Saprolegnia lacteaS.- The ends 



of two hyphae are shown, the ter- 



of movement they usually lose their minal cel i s beil ?g w>osporangia. 



* J In a, the protoplasm is aggregat- 



Cilia, either Withdrawillp- them intO ing about the numerous nuclei (not 



shown). From b many of the zo- 



the protoplasm Or dropping them osppres have escaped through the 



x i 1 o perforation m the wall near the 



off, come to rest, and begin to grow u PP er end °{ J he cel1 - fr ™ c . a11 



have escaped but one, which is just 

 slipping through the opening (here 

 in profile). Magnified 300 diam. — 

 After Kerner. 



into a new plant. 



307. Non - motile spores are 



formed by all classes of land plants without exception 



They 



