470 BOTANICAL GAZETTE [JUNE 
the cell wall appears to be pitted or unequally thickened, many of them 
showing the projections. ‘They are often filled with granular cell con- 
contents anda nucleus. That they are spores which have been arrested 
in their growth, there can be no doubt. In fg. 2. d, ¢, are shown two 
mature spores and two immature ones, all four of them apparently con- 
nected by the same fruiting hypha. Out of thirty mounts only one 
was found to contain the hypha still remaining attached to the imma- 
ture spores. ‘The immature spores are more numerous in ovaries which 
have been completely destroyed and conyerted into spores. They 
are not so numerous in ovaries that still contain parts of their 
F1G. 2.—a, mature spores; 4, imma- 
ture spores; c, an immature spore with 
remains of the fruiting hypha; d¢, two 
immature spores connected with what 
appears to be a sporogenous or fruiting 
hypha; #, broken pieces of mycelium, 
evidently remains of the vegetative 
hyphe. ’ 
starch contents. Often 15 to 20 per cent. of the spores incompletely 
destroyed ovaries are immature and undeveloped, showing that the 
arrested development of these spores is due to an impoverished nutri- 
tion, and probably also to the lack of sufficient space for their complete 
development. 
Cross and longitudinal sections of the culms were made with a 
view to finding the smut mycelium and to determining the probable 
mode of infection. Cross sections of the culms, eight inches below the 
panicles of the diseased rice plants, showed the presence of a mycelium 
similar in every respect to the larger one found in the destroyed ova- 
ties. This mycelium is found only in the sub-epidermal vertical rows 
of loose chlorophyll parenchyma, which lie beneath the rows of stomata 
in the epidermis. In fg. 3, B, are shown bits of mycelium at m. The 
loose chlorophyll parenchyma is connected with the stomata at g. In 
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