258 Scientific Proceedings^ Royal Dublin Society. 



IV. — Description and Position of the Fungus. 



During the long period in which the growth and development of the 

 fungus have been studied, both on various media in pure culture and on its 

 natural host, the flax plant, no method of reproduction other than by conidia 

 has been met with. It is clear, therefore, that for the present, at any rate, 

 it must be placed amongst the Fungi Imperfecti. 



If emphasis be laid on its mode of development on the host, the forma- 

 tion of conidia in definite acervuli would suggest its inclusion amongst 

 the Melanconiales. On the other hand, judging from its mode of growth 

 as a saprophyte on various media, it might well be placed with the 

 Hyphomycetes. 



At the outset the fungus was provisionally ascribed to the genus Gloeo- 

 sporium, but detailed study shows that it cannot remain there. The figure 

 given by Lindau'- of the conidiophores of Microstroma Juglandis Niessl 

 emerging through a stoma recalls at once the behaviour of the ilax fungus. 

 The genus Microstroma has been placed amongst the Exobasidiaceae, but 

 Maire's investigations- show that it should rather be classed amongst the 

 Fungi Imperfecti. In any case, however, in this genus the conidiophores 

 arise from a definite submerged stroma, and no such stroma is developed by 

 the flax fungus. As a matter of fact, the characters of the latter do not 

 admit of its being placed in any genus hitherto described ; hence it becomes 

 necessary to make it the type of a new one. Since one of its leading features 

 is the production of large quantities of conidia, with relatively little develop- 

 ment of mycelium, the name Polyspora is suggested for the genus which 

 will find a place in the Melanconiales. It is eliaracterized as follows : — 



Polyspora nov. gen. 



Mycelium, hyalinum, septatum, intra hospitem ramosum : basidia ex 

 hyphis laxe in cavo substomatali conglomeratis surgentia ' ad summum 

 subtumida et per stomata pauUum protuberantia simplicia vel subramosa 

 ad summum plura conidia quodque gerentia : acervuli numerosi minuti 

 gelatinosi hyalini vel lactei in hospitis epidermide super stomata raro subter 

 siti : conidia hyalina continua obovata vel cylindracea terminis rotundatis 

 complura simul ad summos vel in lateribus basidiorum gesta. 



P. lini. nov. spec. E genere supra descripto; conidiis 9-20;u (medium lOyu) 

 longis 4ju latis nonnumquam cum una vel duabus guttulis. 



Hab. in foliis, stirpibus, fructibus seminibusque vivis Lini usitatissimi 

 in Hibernia. 



1 Lindau, G., Rabeiih. Krypt. Flora. I, 8, p. 19. 



- Maire, R., La structure et la position systeniatjque rles Alicrostrvma et helostroma. 

 Nancy. 1913. 



