OOPHYTA. 135 



Class III. Cceloblaste^. 



280. The plant-body in this important and interesting 

 class is a branched filament, in which the protoplasm is 

 continuous. These plants are, however, not to be consid- 

 ered single-celled, but rather rows of cells which have not 

 become separated from one another by partitions. 



281. The Green Felts ( Vaucheriacem) are good repre- 

 sentatives of the first order under this class. They are 

 coarse, green, tubular plants which grow in abundance on 

 the moist earth in the vicinity of springs, and in shallow 

 running water, forming dense felted masses. 



282. The asexual reproduction consists of a separation of 

 a part of the plant-body, sometimes a swollen lateral 

 branch, sometimes only the protoplasm of such a branch. 

 In the latter case the protoplasm may escape as a zoospore 

 {A, Fig. 63) which eventually forms a wall around itself, 

 and then proceeds to elongate into a new plant-body. 



283. Sexual reproduction takes place in lateral branches 

 also. Both antherids and oogones develop as lateral pro- 

 tuberances upon the main stem {og, og, h, Fig. 63). The 

 male organ (antherid) is long and rather narrow, and soon 

 much curved; its upper portion becomes cut off by a par- 

 tition, and in it very small biciliate antherozoids are de- 

 v^eloped in great numbers. The female organ (oogone) is 

 short and ovoid in outline, and usually stands near the 

 male organs. In it a partition forms near its point of 

 union with the main stem; the upper portion becomes an 

 oogone, and its protoplasm condenses into a rounded body, 

 the germ-cell: at this time the wall of the oogone opens, 

 and permits the entrance of the antherozoids which were 

 set free by the rupture of the antherid-wall. 



