SEXUAL ORGANS 223 



tacles which may be produced on different individual 

 plants. 



The female organ (oogonium) arises from a single 

 cell on the surface of the conceptacle. This grows 

 up to form a papilla which is cut off by a cross wall 

 at the base, and then divides transversely to form a 

 stalk cell and a body cell (Fig. 35, A). The latter 

 becomes large and spherical and its nucleus divides 

 into eight by successive bipartitions. These eight nuclei 

 have different fates in different species. In some the 

 cytoplasm divides correspondingly and eight eggs are 

 formed in the oogonium (Fig. 35, B), but in others 

 four or six of the nuclei degenerate and disappear 

 and the whole of the cytoplasm forms four or 

 only two eggs. In others, again, seven of the 

 eight nuclei degenerate and only one egg is 

 formed from the whole of the protoplasm of the 

 oogonium. 1 The oogonium wall has two layers : the 

 outer bursts, setting free the inner wall as a bladder 

 enclosing the eggs (Fig. 35, C). 



The male organs (antheridia) are club-shaped cells 

 (Fig. 34, A, a), which are branches of a hair that arises, 

 like the oogonium, from a surface cell of the con- 

 ceptacle. The nucleus of the antheridial cell divides by 

 repeated bipartitions to form 64 nuclei (Fig. 34, C, ), 

 and the cytoplasm divides correspondingly so that 

 64 sperms are formed (D). Each of these is a minute 

 biflagellate pear-shaped cell containing besides the 

 nucleus (Fig. 34, D, E, n) a single orange phaeoplast. 

 The mass of 64 sperms is freed from the 



1 This process is essentially the same as the formation of the so- 

 called " polar bodies " of animal eggs. In the animal a brood of four 

 gametes is formed from the mother cell, of which three degenerate 

 (polar bodies), leaving a single egg. In Fucus and allied genera a 

 brood of eight gametes is formed, of which all are fertile eggs, or in 

 some species four, six or seven degenerate. 



