FIG. 1 20. Oogamous sexual reproduction among the Algae. A-D, 

 (Edogonium. A, Part of thread of 0. pachyandrium showing antheridia 

 (a.) with spermatozoids (sp.) ; B, oogonium of O. concatenatum, with 

 two dwarf-males (d.m.) ; C, oogonium of O. diplandrum showing the 

 spermatozoid penetrating into the egg at the receptive spot (r.s.) ; 

 D, antheridia of O . landsboroughi, with escaping spermatozoids. 

 E-G, Vaucheria sessilis. E, Oogonium ($) and antheridium (<$) ; 

 F, oogonium with oospore and dehisced antheridium ; G, spermato- 

 zoids. H-L, Fucus. H, Oogonium with surrounding hairs ; I, 

 branched hair bearing numerous antheridia (a.) ; J, young plant ; 

 K, liberation of spermatozoids ; L, spermatozoid. (A, B, and D after 

 Him ; C after Juranyi ; E-G after Sachs ; H-K after Thuret ; L after 

 Guignard.) 



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