CHYTRIDIALES 



109 



4. Macrochytrium v. Minden {Centralbl. f. Bakt., 8:824, 1902). 



(See also v. Minden, 1911: 385). 



An interesting genus of doubtful relationships based on the 



single species, M. botryoides von Minden, found in Germany 



growing saprophytically on a submerged decaying apple. The 



Fig. 41. — Zygochytrium aurantiacum Sorokin. (a) Mature plant bearing 

 two prosporangia with papillate lids, (b, c) Sporangium emerging from pore 

 after turning aside of lid. (d) Free sporangium, (e) Sporangiurn containing 

 swarmspores. (/, g, h) Swarmsporcs escaping, becoming amoeboid, and ger- 

 minating, {k, m) Conjugation of gametic branches, (n) Mature zygospore. 

 {p) Zygospore germination. {After Sorokin 1874.) 



mycelium is cylindrical and broader than in other members of 

 the order. Superficially the fungus resembles Rhizophidiwn 

 except in its much greater size. The sporangium dehisces by a 

 large hd. Resting spores are unknown. 



Fig. 42.^PoIyrhina muHiformis Sorokin. (a) Thallus and sporangia, (h) 

 Mature swarmsporangia with escaping swarmsporcs. (After Sorokin.) 



5. Rhodochytrium Lagerheim {Botan. Zeitmig, 51: 43, 1893). 



The genus Rhodochytrium, based on R. spilanthidis Lag. para- 

 sitic on the common ragweed, Ambrosia, is of extreme interest 

 to the student of phylogeny. The organism is evidently an 



