188 



SEXUAL REPRODUCTION OF FUCUS 



female gametes are produced in larger sacs or oogonia, which 

 are each supported on a single cell and associated with hair-like 

 chains of cells, paraphyses (Fig. 124, A). Usually eight 

 gametes are developed in each oogonium. The gametes when 

 first discharged from the antheridia and oogonia are enclosed 

 in a delicate cell wall which later ruptures and sets them free 

 (Fig. 124, B). The female gametes are without cilia and as 

 they float away in the water they appear to attract the male 



Fig. 124. Female gametangia : A, greatly enlarged view of one of the 

 oogonia shown in Fig. 122, C. The oogonium is dividing and forming the 

 female gametes ; p, paraphyses. B, the female gametes discharged but still 

 retained in the inner wall of the oogonium. C, greatly enlarged view of a 

 gamete which is surrounded by male gametes, some of which are seen as 

 dark bodies penetrating the cytoplasm of the female gamete. D, early 

 stage in the germination of the gametospore. See later stage, Fig. 121, C. 

 —After Thuret. 



gametes which swarm about them and finally fertilization is 

 effected by one of the male gametes working down to the nu- 

 cleus of the female and fusing with it (Fig. 124, C). In an 

 allied form not only is an attractive substance formed in the 

 female gamete, but probably a repellent one after fertilization 



