HEMIBASIDII. 



113 



to germination, there is no fusion of nuclei, and therefore in this " fusion " there 

 is no sexual act. 



Order 1. Ustilaginacese. Conidiophores with transverse walls and lateral 

 conidia. Ustitago (Fig. 99) generally developes its spores in the floral organs 

 of its host-plant, the ovary or anthers, where they arise from hyphaa, and form 

 a slimy mass which when mature becomes a black dust. 



To this order belong U. avena;, parasitic on Oats, U. hordei and U. nuda 

 (U. jenseni), on Barley; these are the usual cause of " Smut" on cereals. U. 

 hypodytes on straw of Elymus and Agropyrum. U. filiformis in the leaves of 

 Glycerin. U. caricis transforms the fruits of various species of Carex into 

 black, dusty balls. U. violacea developes its violet spore-powder in the anthers 

 of the Caryophyllacete. U. tragopogonis, transforms entire inflorescences of 

 Tragopogon into a black-violet mass. Among the largest are U. grandis, which 

 causes the large swollen nodes in the stem of Pliragmitcs, and the Maize Blight, 

 U. maydis, which produces outgrowths about the size of a hand on the spadix of 

 the Maize. 



Order 2. Tilletiaceae. Conidiophores undivided, generally several conidia 

 arise at their apices. Tilletia tritici, the Stinkbrand on Wheat (Fig. 100). The 

 mycelium lives in Wheat-plants, producing its spores in the ovary after the 

 whole interior of this body has been destroyed by the mycelium, with the ex- 

 ception of the external layer of the wall of the ovary, which remains essentially 

 unaltered and encloses the closely packed, firm mass of spores (Fig. 100 d). 

 The grains of Wheat thus attacked are shorter and thicker than the sound ones, 

 and the ears show the presence of this Fungus by their erect position, and 

 the wide separation of the chaff (Fig. 100 ). The unpleasant odour of the 

 ovary prior to the ripening of the spores, has given the name " Stinkbraud," 

 and, in like manner, its hardness when it encloses the ripe spores, is the reason 

 of its being also called '' Stonebrand." On account of this hardness, the dis- 

 eased grains are readily harvested together with the healthy ones, which become 

 infected by the spores at the threshing. 2'. lacvis (T. fattens) also occurs on 

 Wheat and has smooth brand-spores. 



Entyloma (Fi^. 96), a genus with numerous species, which appear in 

 spots on the leaves of the host-plant, and Tulurcinia (Fig. 98), which makes 

 its appearance on the Primu- 

 laceffi, produce white conidia- 

 spots on the surface of the 

 host-plant. The first-named 

 has single spores, the latter 

 has its spores closely massed 

 together. Urocystis (Fig.101) 

 has its spores surrounded by 

 a number of small and lighter 

 coloured barren spores. U. 

 occulta, Rye-stem Blight, 

 forms its spores in long 

 streaks in the stems and 

 leaves of the Eye, and does 

 considerable damage. U. ce- 



FIG. 101. Urocystis. 1, U. coralloides. A spore-ball, 

 magnified 450 times. 2-4, U. anemones: 2-3, brand- 

 spores which are about to germinate (magnified 450 

 times). 4, Conidia, the two in a state of fusion, a 

 third with vacuoles and division-vrall, magnified 500 

 times. 



W. R. 



