BLASTOCLADIALES 669 



an apical discharge pore. Occasionally, the resting-spore container bore 

 an apical papilla. 



Although Blastocladiopsis parva approaches certain species of Blasto- 

 cladia in similarity of thallus structure, it is readily distinguished. Its 

 resting spores are completely smooth-walled and not punctate. Further- 

 more, they are loose in their containers, rather than filling them (Fig. 47 

 G, I, J) and the zoosporangia may have more than one discharge pore. 



Development of the fungus is remarkably rapid. Within two or three 

 days after the start of a new culture from dried material, plants with 

 mature resting spores are obtained. Sporangia are evidently exceedingly 

 rare (Fig. 47 I). Whiffen suggests that temperature may be a factor 

 inducing their formation. In her material, at 24-25 degrees C. only 

 resting spores formed, but at 21 degrees C. about twelve zoosporangia 

 appeared. 



The complete life history is not yet known. From the scarcity of spo- 

 rangial plants it is not likely that they are gametangial in function. If a 

 sexual stage exists, one possibility is that the resting spores liberate 

 gametes directly and that these fuse and form new sporophytes. No such 

 fusion, however, was noted by Whiffen, and she observed zoospores 

 (from resting spores) develop into plants that bore other resting spores. 



ALLOMYCES E. J. Butler 1 



Ann. Bot. London, 25: 1027. 1911 

 (Figs. 40-43, pp. 616, 622, 626, 629) 



Septocladia Coker and Grant, J. Elisha Mitchell Sci. Soc, 37: 180. 1922. 



Thallus consisting of a cylindrical more or less differentiated trunklike 

 basal cell which gives rise distally to cylindrical dichotomously, sub- 

 dichotomously, or sympodially branched, blunt-tipped successively more 

 slender pseudoseptate hyphae of indefinite extent on which are borne 

 the reproductive organs, contents often alveolately or reticulately 

 vacuolate, anchored to the substratum by a system of endobiotic 



1 A great number of isolates of the various species of this genus have been collected. 

 It is impossible to include them all in the sections devoted to geographic distributions. 

 Consequently, only the source of the original isolate or isolates on which the two 

 phases of the particular species are founded or of those pertinent to its interpretation 

 (ones giving rise to synonyms) is noted. More complete data on all isolates are avail- 

 able in Emerson (1941) and F. T. Wolf (1941a). 



