PHYCOMYCETES 349 



to the cambium zone, the agents in these pathological pro- 

 cesses being Endomyces magnusii, Ludw. ; Saccharomyces 

 ludwigii, Hansen ; and Leuconostoc lagerheimi, Ludwig. 



A very full abstract of all that has been done in this 

 particular branch of vegetable pathology, accompanied by 

 copious references, is contained in Revue Mycologique y 

 1896, by Professor Ludwig. 



FUNGI 

 PHYCOMYCETES 



Vegetative mycelium not forming a compact mass, but 

 ramifying in the living tissues of plants or animals, rarely 

 saprophytic. Asexual mode of reproduction by conidia 

 produced on the surface of the host, which on germination 

 produce zoospores or germ-tubes. Sexual reproduction by 

 zygospores or oospores, produced in the matrix, which 

 germinate only after a period of rest. 



Chytridiaceae. Parasitic on aquatic or aerial plants or 

 animals. Mycelium absent or very rudimentary ; asexual 

 reproduction by zoospores ; sexual reproduction by con- 

 jugation. 



Olpidium, A. Braun. Vegetative condition passive 

 naked protoplasm, the product of one spore. This becomes 

 enclosed in a thin cellulose wall, and forms the zoosporan- 

 gium, the uniciliate swarmspores escaping through a beak, 

 or the wall becomes very thick, and a resting-spore is 

 formed, which gives origin to zoospores. Sexual reproduc- 

 tion absent. 



Parasitic in living cells of plants or animals. 



Olpidium brassicae, Dang., Ann. Sri. Nat., 1886, p. 327 

 (Chytridium brassicae, Wor., Prings. Jahrb., vol. xi. p. 557). 



