422 



BOTANY OF THE LIVING PLANT 



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

 ducing zoospores which are liberated in water. The modification of 



FIG. 357- 



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

 nucleate oogonium (og), and an theridium (an). 2. Albugo Candida. Oogonium with 

 the central, uni-nucleate egg (os), and the fertilising tube (a) of the antheridium which 

 introduces the male nucleus. 3. The same. The fertilised egg (o) surrounded by 

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



such an antheridium as is seen in Vaucheria into the pollinodium of the 

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



FIG. 358. 



Monoblepharis sphaerica. End of a filament with terminal oogonium (o) and an 

 anthendmm (a), i before formation of the gametes, a, spermatozoids (s) escaping 

 and approaching the opening of the oogonium. 3, osp, ripe /ygote and I au 

 empty anthendium. (After Cornu. x8oo.) (From Strasburger ) 



