CEDOGONIUM. 



I03 



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. 103. 



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 zygo- 

 spore develops directly 

 into the thread form of the 

 plant. 



245. Position of cedo- 

 gonium: — CEdogonium 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 

 Confervoidece, that is, the conferva-like alga. . ;., 



246. Relatives of cedogonium. — Many other genera Portion of chanophora 



Fig. 104. 

 Tuft of chagto- 

 phora, natural 

 size. 



are related to cedogonium. Some consist of simple 



showing branching. 



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

 forms is found in chaetophora, represented in figures 104, 105. 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, compact, greenish, rounded mass, which is 



