DIV. I 



THALLOPHYTA 



413 



planogametes, and the corresponding sporangia gametangia. The degree of sexual 

 differentiation varies, and in some cases the swarm-spores produced in multilocular 



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FIG. 355. Ectocarpus siliciilosus. 1, Female 

 garnet* surrounded by a number of male 

 gametes ; seen from the side. 2-5, Stages in 

 the fusion of gametes. 6, Zygote after 24 

 hours. 7-9, Fusion of the nuclei in conjuga- 

 tion, as seen in fixed and stained material. 

 (1-5 after BERTHOLD ; 6-9 after OLTMANXS.) 



FIG. 354. A, Ectocarpus siliculosns. Plurilocular 

 sporangium liberating its contents. (After 

 THURET.) B, C, D, Sphacelaria cirrhosa, de- 

 velopment of the plurilocular sporangium. 

 (After REIXKE.) (From OLTMANXS' Algae.) 



FIG. 356. A, Antheridium ; B, Oogonium of 

 Cutleria multifida. (x 400. After REIXKE.) 



sporangia can germinate without conjugating, as was seen to occur in Ulothrix 

 among the Chlorophyceae. 



Ectocarpus siliculosus (Fig. 354) will serve as an example of the mode of con- 

 jugation of gametes produced from multilocular gametangia. The gametes are 

 similar in form, but their different behaviour allows of their distinction into male 

 and female which are formed in distinct gametangia, borne on the same or different 



