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 antheridium. 

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



Fio. 30. Plasmopara viticola. Vine leaf with white spots on the under .surface, 

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



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

 Inflicts great injury on various wild and cultivated Umbelliferae, 

 e.g. carrot (Daucus Carota), parsley (Petroselinum sativum), chervil 

 (Anthriscus Gcrefolium). 



Plasmopara viticola, Berk. 1 The Downy or False Mildew of 



1 Bibliography. De Bary, Anna/, d. sci. iiat., 1SG3. Viala, Die Pilzi <l. 



Wtinstockes ; with good bibliography. I'rillieux, AnnaL dv. Vi>i*tit. not. 



agronomigue, 1881. Cornu, Le Peronospora f/cs 17;/?/f-. 1'aris, 1882. 



