128 



PHYCOMYCETES. 



arise in tufts from the stomata ; they are branched in various 

 ways, and from each branchlet a single conidium is abjointed. 

 The contents of the conidia emerge as swarming cells with two 

 lateral cilia, or as vesicles which emit a germ-tube. The egg-cells 

 occur singly in each oogonium, and are fertilized by an antheridiuni. 

 The oospores remain long enclosed in the thick-walled oogonium. 



Fio. 39. — Planmopara viticola. Vine leaf with white spots on the under surface, 

 from which tufts of conidiophores emerge, (v. Tubeuf del.) 



Plasmopara nivea (linger). (Britain and U. S. America), 

 lutlict.s great injury on various wild and cultivated Umbelliferae, 

 e.g. carrot {Daucus Carota), parsley (Fet7'oselinum sativum), chervil 

 (Anihriscus Ccrefolium). 



Plasmopara viticola, Berk.^ The Downy or False Mildew of 



' Bibliography. De Bary, Annal. d. tici. nat 

 Weinstockts ; with good bibliography. Prillieux, ^ 

 agroiiomigm, 1881. Cornu, Le Peronosnora des Vh 



18G3. Viala, Die Pike d. 

 Annal. de. Vinstit. nat. 

 ignes, Paris, 1882. Sajo^ 



