724 



FUNGI 



tion the exospore splits and a conidiophore or promycelium is 

 produced which differs from that of the Ustilaginacese in being 

 undivided, and its conidia instead of being laterally developed 

 arise in a whorl at the apex of the conidiophore (b. Fig. 244). 

 When growing in water the conidiophore often becomes divided 

 by cross septa, but the protoplasm is continually transferred to 

 the apical cell. The conidia, which only make their appearance 

 when the conidiophore is exposed to damp air, are narrow and 

 thread-like, and are usually from six to eight in number ; they 

 sometimes become joined together in pairs as at e. Fig. 244. 



After falling from the conidiophore, or even before this 

 happens, these primary conidia, when kept in damp air, ger- 



FlG. 244. — a Cblamydospores of Bunt {TilUtia tritici Bjerk.) en- 

 larged about 500 diameters) ; b germinated chlamydo'^pores ; c conidio- 

 phores ; c conidia, two of which are united ; _/" germinated conidium 

 producing a secondary conidium r ; d secondary conidium germinating ; 

 n mycelium produced from primary conidium (enlarged about 300 

 diameters). 



minate and give rise to a thin, short hypha on which single 

 conidia of the second order (r) are produced, and these may 

 furnish conidia of the third order. The secondary and tertiary 

 conidia are slightly crescent or sickle-shaped and of very variable 

 size. 



When grown as a saprophyte the conidia may produce a 

 mycelium («) from which numbers of secondary and tertiary 



