370 



BOTANY 



PAKT 11 



expressed in their sliape and size. The Cutleriaceae atlord a particularly good 

 transition from isogamy to oogamy and a differentiation of the gametangia into 

 antheridia and oogonia (Fig. 295) (^). 



Fio. 293. — A, Eclmarpus sUiniliisuii. Plurilocular 

 sporangium liberating its contents (after 

 Thuuet). B, C, D, Sphacelaria cirrlwsa, dc- 

 veloiiniRiit of the iilurilofular sporangiui]i 

 (after Beinke). (From Oltmanns' Algt'c) 



Fig. 204. — Ectocarjms siliculosus. 1, Female 

 gamete surrounded by a number of male 

 gametes ; seen from the side. 2-6, Stages in 

 the fusion of gametes. G, 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 Oltmanns.) 



Fi(i. 295. — A, Antheridiuni ; B, Oogonium of 

 CtMeria mnUifida. (After Reinke, x 400.) 



Order 2. Cyclosporeae (^"' •"'") 



Family l. Dictyotaceae.— Only a small number of forms belong to this 

 family. Tlie fan-shaped radinu 'pavonia, which occurs in the Jlediterranean, and 



I 



