422 



BOTANY OF THE LIVING PLANT 



through the air. But it shows its real nature on germination by pro- 

 ducing zoospores which are Hberated in water. The modification of 



Fig. 357- |] 



Fertilisation of the Peronosporeae. i. Peronospora parasitica, young multi- '; 



nucleate oogonium (og), and antheridium (aw). 2. Albugo Candida. Oogonium with I' 



the central, uni-nucleate egg {os), and the fertiUsing tube (a) of the antheridium which I ^ 

 introduces the male nucleus. 3. The same. The fertilised egg (0) surrounded bj^ 



periplasm (/>). (After Wager. x666.) (From Strasburger.) I 



: f 



such an antheridium as is seen in Vaucheria into the polhnodium of the \ 

 Peronosporeae, is a comparatively sHght one: the latter does not liberate 



i 5 



Fig. 358. 

 M onoblepharis sphaerica. End of a filament with terminal oogonium (0) and an 

 antheridium (a), i, before formation of the gametes. 2, spermatozoids (s) escaping 

 and approaching the opening of the oogonium. 3, osp, ripe zygote and an 

 empty antheridium. (After Comu. x8oo.) (From Strasburger.) 



