t. J. F. SHAW. 15 



frequently branch. A transverse septunj occurs at the point of 

 origin of a branch and not some distance from it (PI II, Fig. 11, 

 cp. Rhizoctonia). The sclerotia are roughly circular and vary in 

 diameter from 1 50 — 500m. i'hey arise from a plexus of interlacing 

 hj^phai, which continue to branch and intertwine until a small 

 spherical compact mass is formed. For a time the young 

 sclerotium increases in size by the adhesion of fresh branches to 

 the periphery ; ultimately, the cell walls turn black and all 

 further growth ceases. At this stage the interior of the 

 sclerotium has a very definite parenchymatous structure, and it is 

 almost impossible to discern that it has been formed by inter- 

 weaving hyph^e ; a thin layer of loosely intertwined hyaline 

 hyphse can, however, be seen investing the exterior. Not infre- 

 quently several sclerotia become united, forming an incrustation 

 on the medium resembling a stroma : this was particularly 

 common in cultures on maize meal. 



In culture upon glucose agar, at an early stage, before the 

 appearance of sclerotia, the mycelium along the edge of the agar 

 appears black. An examination of the hyphse at this region 

 shows that they are more or less smoky coloured and of very 

 irregular shape (PI. II, Fig. 5) ; they frequently terminate in 

 curious appendages. These appendages may consist of one or 

 more cells ; they are very much darker in colour than the cells of 

 the hyphse, but resemble them in their irregular form (PI. II, 

 Fig. 6). In some cases the parent hypha was attached to the centre 

 of the appendage in such a way that the latter was l)orne in a 

 peltate manner (PI. II, Figs. 7, 8). Infection upon glucose agar 

 from these hyphse and appendages produced cultures of the 

 normal type resembling the parent culture. The fact that these 

 structures are produced along the edges of the agar, in contact 

 with the glass, suggested that they might be appressoria. If tliis 

 is the case, it is not easy to understand why their formation 

 should be restricted to one sort of aoar medium : in no case were 

 they produced upon anything but glucose agar. 



Infection upon nutrient agar containing extract of paddy 

 grains gave rise to a rather different lial)it of growth. Tlie 



