TILLETIA TRITICI 



22' 



\? liit nig — Tilletia tritici. Diagrams illustrating abnormalities in the develop- 

 ment of the basidium : in A two secondary conidia (the authors' basidio- 

 spores) instead of being discharged have germinated in situ ; and in B 

 two H -shaped pairs of primary conidia (the authors' primary sterigmata) 

 instead of producing secondary conidia have germinated directly. A : the 

 chlamydospore a has developed a promycelium (basidium-body) b con- 

 sisting of one dead basal cell and a living apical cell ; the latter bears 12 

 primary conidia which have conjugated in pairs ; four of the H -shaped 

 pairs, as at c, have not yet produced secondary conidia and are full of 

 protoplasm ; two of the pairs, d and e, have each produced a short lateral 

 sterigma / bearing a secondary conidium, g and h ; the conidia g and h, 

 owing to a failure in the drop-discharge mechanism, have not been shot 

 away, and they have germinated in situ ; the protoplasm is passing from 

 the conidia into the germ-tubes i i ; the septation of the H -shaped pairs 

 of primary conidia d and e and of the secondary conidium h took place 

 during the evacuation of the protoplasm. B : the chlamydospore a has 

 developed a promycelium 6 consisting of one curved living cell which bears 

 8 primary conidia that have conjugated in pairs ; two of the H -shaped 

 pairs, as at c, have not produced either secondary conidia or germ-tubes 

 and are full of protoplasm, while two of the pairs d and / instead of giving 

 rise to secondary conidia have germinated directly ; protoplasm is still 

 creeping out of the H shaped pair of primary conidia d into the germ-tube 

 e, but it has entirely vacated the pair / and is now in the germ-tube g ; 

 septation is accompanying or has accompanied the evacuation of the proto- 

 plasm from the conidia-pairs d and /, and already there is one septum in 

 the germ-tube g. Such H -shaped pairs as d and e in A and d and / in B 

 readily become detached from the promycelium b and fall on to the 

 substratum where, if nutriment is present, the germ -tubes may develop 

 into mycelia. Magnification, 660. 



