24 PHYCOMYCETES 



none of them is there anything more than a rudimentary form of 

 sexuality. 



There is much difference of opinion in the matter of classifica- 

 tion. Over two hundred species arranged in some forty genera 

 are usually recognized. Various members of this group show 

 affinities with the Myxomycetes and others with certain forms of 

 Basidiomycetes (Ustilaginales). Except Synchytrium, the Ameri- 

 can forms of this order have scarcely been studied. 



LITERATURE. 



Fischer. Rabenhorst's Kryptogamen Flora Deutschland, 

 Oesterreich und der Schweiz. i 4 : 3-5, 11-160. 1892, is the 

 best monograph of these forms. A somewhat different generic 

 arrangement appears in 



Schroeter. Die natiirlichen Pflanzenfamilien, i 1 : 64-92. 1892-3. 

 In both of these works citations of the extended but widely scat- 

 tered European literature will be found. 



Descriptions of the species will also be found in 

 Saccardo. Sylloge Fungorum, 7 : 286-322 ; 9 : 357-363 ; n : 

 246-251. 



The American forms of Synchytrium are described in 

 Farlow. The Synchytria of the United States. Bot. Gaz. 10 : 

 235-245. PL 4. 1885. 



Order 2. MUCORALES. 



The order Mucorales includes the more common moulds which 

 are found on various organic substances, with the exception of the 

 ordinary green mould which belongs to another order of fungi. 

 These true moulds are either saprophytic on various organic sub- 

 stances or are parasites on other moulds. The common Mucor 

 stolonifer* will illustrate well the habit and structure of the order. 

 The plant body consists of irregular branching hyphae from which 

 arise lateral branches which form at intervals two sorts of second- 

 ary branches, the one descending and forming root-like holdfasts, 

 the others erect and bearing sporangia. These sporangia contain 

 a large number of conidia which are dark colored at maturity and 

 give the ripe sporangium a black appearance. These conidia 

 asexually produced are the ordinary method of reproduction in 



*Also known under the name of Rhizopus nigricans. 



