VEGETA TIVE EEPKOD I'CT lOK. 



2'3 



When zoospores possess chlorophyll-bodies, as thev fre- 

 quently do, they are aggregated at 

 the larger end, leaving the pointed 

 end to which the cilia are attached 

 colorless. Zoospores are ibrmed 

 either in a general body-cell, not 

 visibly dilTerent from the other 

 bodv-cells, or in a cell specialized 

 in form and structure. In either 

 case the cell in which they are pro- 

 duced is called a zoospiorangiuni. 

 The entire contents of the zoospo- 

 rangium may form a single zoospore, 

 or it mav divide into se\"eral 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 w-all of the sporangium or b^• 

 the solution of a portion of the wall 

 (fig. 2oSj. They may begin to 

 move before the rupture of the wall, 

 in accomplishing which their activ- 

 ity may materially assist. They 



then work their wav out and swim Fi'"- 208.— Development and escape 



of zoospores of an aquatic ftine:us 



freelv in the water. After a time (Sa/'rolegnia lactea). The ends 



of two hyph^e are sho«n, the ter- 



of movement thev USUliHv lose their ™-^A cells being zoosporangia. 

 -^ • In ,! . tl 



cilia, either withdrawing them into 



. the protoplasm is ageregat- 

 ing about the numerous nuclei (not 

 shown). From h many of the zo- 

 tlie protoplasm or droijpintr them ospores have escaped through the 

 ^ ' *- perforation in the wall near tlie 



off, come to rest, and begin to grow "pper ™d of the cell. From c all 



^ ^ ha\-e escaped but one. which is just 



into a new plant. sHpping through the opening (here 



in profile). Magnified 300 diam. — 



307. Non- motile spores are 



After Kerner. 



formed by all classes of land plants without exception. They 



