134 THE LOWER FUNGI— PHYCOMYCETES 



B. Thallus lacking pseudosepta, not definitely constricted. 



3. Blastocladia, p. 136 



1. Gonapodya Fischer (1892: 378). 



A small genus of two species, G. siliquaeformis (Reinsch) 

 Thaxter and G. polymorpha Thaxter. The genus is of somewhat 

 doubtful affinities, and is placed here chiefly on account of its 

 uniciliate zoospores and non-cellullose walls. In its prominently 

 segmented mycelium it corresponds to the members of the 

 Leptomitaceae of the Saprolegniales. Since the species are 

 known only in the sporangial condition and lack the pecuHar 

 resting sporangia of Blastocladia and Allomyces, the incorporation 

 of the genus here is at best tentative. 



Fig. oO.— Allomyces arhuscula Butler, (a) Pseudosepta as seen in longitudinal 

 section, (h) Same in transverse section. {After Barrett 1912.) 



The thallus is filamentous, resembling somewhat that of Lep- 

 tomitus, but with shorter segments (Fig. 49). A basal portion 

 attached to the substratum by rhizoids is lacking. The hyphae 

 are usually deeply constricted, so much so that at times the short 

 rounded segments give the aspect of a chain of beads. Branching 

 occurs chiefly at the tips of the primary hyphae, dense tufts 

 of segmented branchlets terminating slender more or less unseg- 

 mented threads. The sporangia are borne terminally, and 

 undergo repeated proliferation. They are elongated and taper 

 toward the tip. The zoospores are typically uniciliate, though 

 biciliate spores apparently sometimes exist. 



The species occur on submerged fruits, twigs, and other plant 

 parts and are saprophytic. 



