224 GENERAL MORPHOLOGY OF PLANTS 



rest, attaches itself to a place of support by a disk-like grappler, 

 and grows into another (Edogonium thread. In sexual repro- 

 duction certain cells become transformed into female organs by 

 becoming enlarged and rounded. This enlarged cell is the egg 

 case (oifgenium, or egg producer), and contains a single large 

 egg or oospore. Other cells become divided into smaller cells 

 by cross walls. Each of these small cells is a male organ, the 

 sperm case (antheridium). The sperms are like the swimming 

 spores, but much smaller and devoid of chlorophyll. One enters 

 an egg case, passes into the egg and unites w r ith the nucleus. 

 The fertilized egg (oospore) then acquires a thick wall and 

 becomes a resting spore. After a period of rest the proto- 

 plasm of the fertilized egg forms four zoospores, each of 

 which can grow into an (Edogonium plant, thus completing 

 the life cycle. In some species both the sperm case and egg 

 case are on the same thread, while in other species they aie 

 on separate threads. In still others small male plants are 

 first formed from a special swimming spore intermediate in 

 size and color between a zoospore and sperm. 



Sporophyte 



Zygote n~T) Mother cell 

 Sperm 



Antxwgon. 



Diagram No. II. Illustrating the life cycle in the development of (Edogonium. Course 

 of development follows the direction indicated by arrows. Zygote equals fertilized egg. 

 Asexual multiplication by asexual spores. ^ 



366. Coleochaete. Coleoch&te .represents the highest stage 

 of development of the filamentous green algae. The plants 

 occur in Afresh water attached to larger aquatic plants. They 

 are mostly filamentous and branched, but a few form small, 



