SAPROLEGNIALES 29 



Brefeld. Botanische Untersuchungen liber Schimmelpilze, 4 : 

 1881; 6 : 1884. 



Thaxter. The Entomophthoreae of the United States. Mem. 

 Boston Soc. Nat. Hist. 4 : 133-201. PL 14-21, 1888. 



Order 4. SAPROLEGNIALES. 



The order Saprolegniales contains mostly aquatic moulds which 

 live on dead flies, dead fish, or quite commonly attack living 

 aquatic animals, commonly young fish. They have been called 

 fish-moulds, and the disease they engender has been known in 

 England as the salmon disease. Sometimes they become very 

 conspicuous, forming branching masses two or three inches, 

 high. They are commonly much less conspicuous, however. 

 Certain species are capable of living in the tissues of various 

 plants, one of which, Artotrogus DeBaryanus* is a common cause 

 of the phenomenon of damping off, commonly known to gar- 

 deners as a destructive disease of young seedlings, though sev- 

 eral other fungi will produce a similar disease. In the truly aquatic 

 species the asexual reproduction is accomplished by zoospores. 

 In the semi-aerial forms (Pythiaceae),f the asexual reproduction 

 as accomplished by conidia. The sexual method of reproduction 

 in both families is accomplished by means of the fertilization of 

 egg-cells by antherids. 



LITERATURE. 



Schroeter. Loc. cit 93-197. 



Fischer. Loc. cit. 310-383. 



Saccardo. Sylloge Fungorum, 7 : 264-280 ; 9 : 345-349 ; 

 ii : 244-245. 



Humphrey. The Saprolegniaceae of the United States, with 

 notes on the other species. Trans. Amer. Philos. Soc. 17 : 63- 

 148. PL 14-20. 1892. 



Thaxter. Observations on the genus Naegelia of Reinsch. 

 Bot. Gaz. 19 : 49-55. PL J. 1894. 



Thaxter. New or peculiar aquatic fungi. Bot. Gaz. 20 : 433- 

 440, PL 29; 477-485. PI- 3 1 - 1895. 



* Formerly known as Pythium DeBaryanum. 



f Fischer (loc. cit. ), with apparently good reason unites the conidia-bear- 

 ing Pythiaceae with the Peronosporales and also unites the aquatic Mono- 

 blepliaridaceae with the Saprolegniales. 



