OOPEYTA. 



139 



a thick integument, which is double — that is, formed of an 

 outer thicker coat (epispore) and an inner thinner one (en- 

 dospore). After a considerable period of repose the rest- 

 ing spores germinate by sending out a tube, as in Green 

 Felt. 



289. The Pond-Seum Parasites are minute plants living 

 in the cells of Pond-scums, Desmids, Diatoms, etc. In one 

 family {Ancylisteoe) they are tubular, branching filamentSj 

 while in Ghytridiece they consist of rounded or branching 

 cells. Both zoospores and resting-spores are usually pro- 

 duced, the former escaping from the end of a branch which 

 has pushed out through the wall of the host.* The^ Gall- 

 fungi (^Synchytriem) of many flowering plants are probably 

 related to the foregoing. They produce swollen, rust- 

 'jke vesicles in the epidermal cells, 

 in which reddish or brownish zoo- 

 spore-producing spores are formed. 



290. The Mildews and White 

 Rusts {PeronosporecB) live parasiti- 

 cally in the interior of higher plants. 

 They are composed of long branch- 

 ing tubes, whose cavities are con- 

 tinuous throughout. They grow 

 between the cells of their hosts,* 

 and draw, nourishment from them 

 by means of little branches {haus- 

 toria), which thrust themselves 



., , ,1 ,1 /xn- ni-\ Fia. 65.— Showing one of the 



through the walls (.big. 65). hyph^ (m, m) of a Mildew, 



—.^ , / . T \ sending suckers (haustoria) 



291. The asexual spores (conidia) into the eeus («, z) of its hosfj 



, » 1 Magnified 300 times. 



are produced upon branches oi the 



* The plant or animal upon which a parasiite feeds is callei] its Ao?t 



