14 A SCLEROTIAL DISEASE OK RlCEl. 



t'ornied in the intercellular spaces between the main vas-cular 

 bundles. This is clearly shown in PI. Ill, Fig. 1. The section 

 shows only the inner portion of the stem ; a young sclerotium 

 can be seen in one of the larger air cavities and the collapsed 

 nature of the innermost layev of cells, in the vicinity of the two 

 larger sclerotia, is apparent. In some of the cells hypha? are 

 distinctly visible ; they are, however, more clearly shown in PL 

 III, Fig. 2, from the same section. At first sight the sclerotia 

 strongly resemble that of Rhizoctonia Solani, Kiihn : they are, 

 however, considerably larger and have a distinctly .smooth shiny 

 surface. In section the younger sclerotia appear to consist of 

 fairly small })arenc]iymatous cells, the outer cells being more 

 or less definitely arranged in concentric layers. (PI. Ill, Fig. 1). 

 In fact, at this stage, there is a distinct difterentiation into 

 cortical and medullary zones. In the more mature sclerotia 

 the difterentiation into cortex and medulla is not so apparent, 

 while the cell walls are thicker and <»f a sharp black colour 

 (PI. Ill, Fig. :3). 



Cultures. 



From diseased plants, such as those just described, cultures 

 were obtained on agar. It may be stated here that in all cases, 

 whether the cultures were made from hyplne or sclerotia, and 

 whether the material came from Burma^ Samalkota or Pusa, the 

 same fungus was obtained in culture. Cultures were made 

 on media of widely dift'erent composition, and, in some cases, the 

 nature of the nutrient substratum was n(»t without infiuenct- on 

 the charactei' of the funefal i>rowth. 



Growth appeared to be most vigorous on glucose agai-. An 

 infection upon this medium resulted in a copious development of 

 white hyplue, followed, after five or six days, by the appearance 

 of sclerotia. The .sclerotia are at first visible as miimte circular 

 spots of a greyish colour ; subsequently they become black and 

 shiny, exactly resembling those found in the lice plant. The 

 hyphaj aie of the usual type, the cells being about 4 — G/u bioad 

 and 1.50 — 3.")0/u long, the}' contain numerous oil globules and 



