260 THE VEGETABLE WORLD. 
on the diseased tissues of plants. The spores are single, often par- 
titioned on more or less distinct spherospores, the flocci of the fruit 
obsolete, or mere peduncles. The Smut, properly so-called, Ustilago 
segetum, particularly attacks oats and barley. It develops itself 
in the parenchyma of the floral envelope, in the axes of the 
spikelet, and in the peduncles of the Graminwx. When the 
Fig. 325. Bundles of Spores. Fig. 326. 
wind has dispersed the spores of the parasite, the plant only 
remains a blackened skeleton, and scarcely recognisable. The 
presence of the fungale draws after it the abortion more or less 
complete of the organs of the flower which it has attacked, the 
sterility of the spike, and a notable alteration of their normal 
structure. 
Another species, Ustilago Maydis, with black spores, is equally 
disastrous to the cultivators of Maize or Indian corn. 418: 27 
represents a spike of maize with white grains. Fig. 328 presents 
the vertical section of an ovary surrounded with bracts, tumified 
by the pressure of the fungus. The black spots indicate the 
formation at these points of the black powder of Ustilago Maydis. 
This fungus attacks alike stem and spikelet, producing uP it 
excrescences more or less voluminous and deformed. “In dissect- 
ing the ordinary excrescences while they are still gorged with 
juices,” says M. Tulasne, “we find them to be formed of 
parenchyma of great cells, frequently with gaps, and trave 
by a small number of fibro-vascular bundles; it is a structure 
analagous to that presented by the bracts and ovary invested by 
entophytrio. The chasms in this parenchyma, and frequently even 
the interior of its constituting cells, are filled in some cases, ae 
they are examined before the final pulverescence of the Ustilag? 
