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Practical Plant Biology. 



They are of two kinds oogonia and 



the gametes are found, 

 antheridia. 



The beginnings of these two organs resemble those of the hairs. 

 A cell from the cortex forming part of the wall grows out into the 

 conceptacle ; as it elongates it divides transversely. The terminal 

 segment projecting into the cavity becomes an oogonium or an 

 antheridium as the case may be. The basal segment forms its 

 stalk. In the case of the oogonium the terminal cell enlarges 



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FIG. 19. Fucus platycarpus, receptacle, transverse section passing through 

 a conceptacle, microphotograph, x 100. a, antheridia ; o, oogonia ; 

 p, paraphyses (hairs). 



greatly and becomes ovoid so that it is just visible to the unaided 

 eye. It is filled with dense protoplasm and is olive-brown owing 

 to the large number of chromatophores it contains. Its nucleus 

 divides and the resultant nuclei undergo two successive divisions, 

 so that there come to be eight nuclei in the protoplasm of the 

 oogonium. Round this mass two separate membranes are formed 

 within the original cell-wall of the oogonium, and the mass divides 

 into eight pieces each containing one nucleus. By the successive 

 liquefaction and rupture of the original cell-wall and of the outer 



