148 



MORPHOLOG Y. 



fertilization, is the egg cell. In those cases where the brown body 

 with a thick wall is present fertilization has taken place, and this 

 body is the fertilized egg, oroospore. It contains 

 large quantities of an oily substance, and, like 



Fig. 144. 



Portion o f 

 thread of oedo- 

 gonium, show- 

 ing chlorophyll 

 grains, and pe- 

 culiar cap cell 

 walls. 



Fig. 145. 



CEdogonium undulatum, with oogonia and dwarf males; 

 the upper oogonium at the right has a mature oospore. 



the fertilized egg of spirogyra and vaucheria, is able to with- 

 stand greater changes in temperature than the vegetative stage, 

 and can endure drying and freezing for some time without 

 injury. 



In the oogonium wall there can frequently be seen a rift near 

 the middle of one side, or near the upper end. This is the 



