(EDOGONIUM. 151 



cell. The sexual organs are differentiated among themselves, the antheridium 

 is small, and the oogonium large. The gametes are also differentiated in 

 size, and the male gamete is motile, and carries in its body the nucleus 

 which fuses with the nucleus of the egg cell. 



But a more striking advance is the fact that the fertilized egg does not 



Fig. 152. 



' Fertilized egg of cedogonium after a period of rest escaping from the wall of the oogonium, 

 and dividing into the four zoospores. (After Juranyi.) 



produce the vegetative thread of cedogonium directly, but first forms four 



zoospores, each of which is then capable of developing into the thread. On 



the other hand we found 



that in spirogyra the zygp- 



spore develops directly 



into the thread form of the 



plant. 



320. Position of cedo- 

 gonium. GEdogonium is 

 one of the true thread-like 

 algae, green in color, and 

 the threads are divided 

 into distinct cells. It, 

 along with many relatives, 

 was once placed in the old 



genus conferva. These are all now placed in the group 

 Confervoidea, that is, the conferva-like alga. v , 



321. Kelatives of cedogonium. Many other genera Portion of chsetophora 

 are related to oedogonium. Some consist of simple showing branchmg. 

 threads, and others of branched threads. An example of the branched 

 forms is found in chastophora, represented in figures 153, 154. This plant 

 grows in quiet pools or in slow-running water. It is attached to sticks, rocks, 

 or to larger aquatic plants. Many threads spring from the same point of 

 attachment and radiate in all directions. This, together with the branching 

 of the threads, makes a small, corrpact, greenish, rounded mass, which is 



Fig. i S3- 

 Tuft of chzto- 

 phora, natural 



s i ze . 



