SEXUAL REPRODUCTION. 



28; 



Simple ovaries occur only in the algae and fungi, where they 

 are known as oogonia or carpogonia. They are either pro- 

 duced by the modification of one of the cells of a filament 

 (fig. 325), or they are the terminal cell of a special branch 

 (fig. 308). Usually the ovary is decidedly larger than the or- 

 dinary vegetative cells. The fertilized egg often becomes a 

 resting spore (fig. 325). 



In the higher algae, especially the marine algae, the ovaries 

 are often aggregated in special pits, the conceptacles, as in 



FIG. 326. A section through a female conceptacle of bladder wrack (Fucus vesiculo- 

 s?ts) ; showing form of pit, the numerous hairs with which it is lined, and ovaries in 

 various stages of development. In the tissue about the pit note the cortex of densely 

 placed cells and the loose network of filaments in the interior. Magnified sodiam. 

 After Thuret. 



Fucus (figs. 42, 326). Here the ovary is formed by the en- 

 largement of the terminal cell of a two-celled outgrowth from 

 the surface (fig. 327). The eight eggs are set free and are 

 fertilized in the water by the motile sperms (fig. 324). They 

 grow at once into new plants. 



The simple ovary is surrounded in Chara (fig. 313) by a 

 jacket of spirally coiled cells, which grow up from beneath it 

 and make it look as though it were compound (*[ 390). 



