!^6 FUNGOUS DISEASES OF PLANTS 



composed, however, largely of saprophytic organisms, and a fourth 

 order, Entomophthorales, contains forms which are for the most 

 part parasitic upon insects. There remain therefore three orders 

 which are important from the standpoint of diseases in plants, viz., 

 Chytridiales, Saprolegniales, and Peronosporales. 



I. CHYTRIDIALES 



F\KI,O\V, W. G. The Synchytria of the United States. Bot Gaz. 10: 235- 



245- //. 4- '- S ' S 5- 

 HARPER, R. A. Cell-Division in Sporangia and Asci. Ann. Bot. 13: 467- 



525. pis. 24-26. 

 KrsANo. S. On the Cytology of Synchytrium. Centrbl. f. Bakt., Paras, u. 



Inf. 19(Abt. II): 53 8 ~543- P l - 7 - I 97- 

 NOWAKOWSKI, L. Beitrag z. Kenntnis d. Chytridiaceen. Cohn's Beitrage z. 



Biol. d. Pflanzen 2: 73-rioo, 201-219. pis. 4-6, 8-g. 1876. 

 RVTZ, WALTER. Beitrage zur Kenntnis der Gattung Synchytrium. Centrbl. 



f. Bakt, Paras, u. Inf. 18 (Abt. II): 635-655, 799-825. 1907. 

 SCHROETER, J. Die Pflanzenparasiten aus der Gattung Synchytrium. Bei- 

 trage z. Biol. d. Pflanzen. 1 : 1-132. pis. i-j. 1870. 

 SCHROETER, J. Chytridineae. Pflanzenfamilien (Engler and Prantl) 1 (i* 



Abt): 64-87.^.^-77. 1892. 

 ZOPF, W. Ueber einige niedere Algenpilze. 1887. Halle. 



In a consideration which might include several hundred fungi 

 of greatest economic importance, as disease-producing organisms 

 of the flowering plants, doubtless no mention would be made of 

 the above order. The order should, however, receive at least casual 

 attention at the hands of the student, owing to the important posi- 

 tion which it occupies as the lowest of the true fungi. It is a strik- 

 ing fact that a considerable majority of these lower fungi are parasitic 

 upon protozoa, algae, and other fungi. Some, however, are para- 

 sitic upon higher plants. 



These plants are all very simple, and there is no member of 

 the family which possesses a true mycelium, although delicate 

 branches of the fungous body occur. Reproduction is accom- 

 plished by means of motile spores, or swarm cells, produced in 

 sporangia. In higher forms cell fusions occur. It is not certain 

 what these fusions denote. 



II. SYNCHYTRIACE^: 



In this family are included the majority of the Chytridiales 



parasitic- upon higher plants. They occur for llu- most part only 



