VEGE TA Tl I E REPROD UCTION. 



213 



When zoospores possess chlorop 

 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 

 freely in the water. After a time 

 of movement they usually lose their 

 cilia, either withdrawing them into 

 the protoplasm or dropping them 

 off, come to rest, and begin to grow 

 into a new plant. 



307. Non -motile spores are 

 formed by all classes of Land plants 



l'n. 208 -Development and escape 



of zoospores of an aquatic fungus 

 {Saprolegnia lactea). The ends 



ot two hvph.e are shown, the ter 



minal cells being goosporangia 



In ,;. the protoplasm 1 



ing about the numerous nui lei (no 



shown). From 6 many ol tin- ZO 

 ospores have escaped through the 

 perforation in the wall near the 



upper end of tin- .ell. From ."11 



have est aped hut one. whk h is just 



slipping through the opening ( here 



in profile). Magnified 300 diam. — 



Aftei kerner. 



without exception. They 



