. Pig. ioi. — Usiilago avcitac. i, a ' snuilti-d ' car of oats ; 2, spores ; 3, gi minating spores ; 4, secondary spores conjugating. Figs. 2-4 highly mag. to be of a dark olive-green colour, as seen through the tissues forming the membrane. When mature the blisters burst and liberate a dense powdery mass of black spores. The heads are most frequently attacked, and the galls may attain to the size of an apple, sometimes larger. Infection may occur at any young, growing portion of the plant. Tlie spores are irregularly globose, dark brown, delicately spinulose, 9-12 /x diam. I

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Keywords: ., bookpublishernewyorkmacmillan, booksubjectplantdis, bookyear1910