I'EGE TA TI I 'E 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 (Saproiegnta lactea). The ends 



of two hyphas are shown, the ter- 

 minal cells being zoosporangia. 

 In/7, the protoplasm is aggregat- 

 ing about the numerous nuclei (not 

 shown). From b many of the zo- 

 ospores have escaped through the 

 perforation in the wall near the 



off, come to rest, and begin to grow 

 into a new plant. 



307. Non motile spores are 



formed by all classes of land plants without exception. They 



of movement they usually lose their 

 cilia, either withdrawing them into 

 the protoplasm or dropping them 



upper end of the cell. From c all 

 have escaped but one, which is just 

 slipping through the opening (here 

 in profile). Magnified 300 diam. 

 After Kerner. 



