BUTLER AND HAFIZ 183 



In the hollow which invariably forms in the pith of affected 

 internodes at a late stage in the disease, there is usually a 

 copious greyish-white, ilufty growth of hyphte, similar to those 

 found m the tissues, and bearing great numbers of conidia, 

 resembling those observed in the vessels, though often of some- 

 what laro-er size. The characters of the funsjus can be studied 

 from this growth or, more satisfactorily, from pure cultures, and 

 they show it to be a member of the form-genus Ceplicdo^porium, 

 several species of which are known to be lower stages in the 

 development of Ilypocreacece. 



The hypha) are hyaline, slender (about 3 to 5 /« in diameter), 

 richly branched, sparingly septate when young, not varying 

 abruptly in diameter, though swollen segments are found in old 

 cultures. Sometimes the individual filaments unite toofether to 

 form coremial strands, usuall}^ only two or three hypha? taking- 

 part in the formation. An early stage of such a strand is shown 

 in Fig. 6ri. Chlamydospores have not been observed either in 

 culture or in diseased canes. 



The conidia are borne on short, simple or branched, lateral 

 hyphse and also terminall}' on the ultimate branches of the 

 mycelium. They measure 4 to 12 m (usually 5 to 8 /x) by 2 to 

 3 M, when formed, but increase in size prior to germination. Their 

 shape varies from shortly oval to ovoid oi' long elliptical. Occa- 

 sionally they are curved or with one side flattened. The}? are 

 almost inv'ariabl}^ unicellular when formed, but some become 

 septate prior to germination, the septa being 1 to 3 in number 

 (Fig. 11). Spores and mycelium are hyaline. 



The conidiophores are usually of definite shape, measuring 

 from 6 to 30 u b}^' 3 to 4 // at the thickest part, swollen slightly 

 in the middle or lower third, narrowing below where they arise 

 from the mycelium and tapering above, but with an obtuse apex 

 on which the spores are borne (Fig. 7). They may be scattered 

 along the hypha or arise in bunches near together (Fig. 6). 

 Branchino^ is not uncommon, beincj irregular or once whorled or 

 forked. Each branch usually bears conidia at the apex, but if 

 kept very moist the branches may grow out into long hyphse. 



