Diseases of plants induced by Diseases of plants induced by cryptogamic parasites; introduction to the study of pathogenic Fungi, slime-Fungi, bacteria, & Algae diseasesofplant00tube Year: 1897 POLYPOKITS. 449 but later becomes brown, and, on being touched, deep red. The spores are white, and various forms of hairs occur among the basidia. Young sporophores appear as little brown cushions on felled timber, also on living stems of pine, and, according to Magnus, on Weymouth pine. The disease generally makes its first appearance in roots and lower parts of the stem, spreading thence into highe
Diseases of plants induced by Diseases of plants induced by cryptogamic parasites; introduction to the study of pathogenic Fungi, slime-Fungi, bacteria, & Algae diseasesofplant00tube Year: 1897 POLYPOKITS. 449 but later becomes brown, and, on being touched, deep red. The spores are white, and various forms of hairs occur among the basidia. Young sporophores appear as little brown cushions on felled timber, also on living stems of pine, and, according to Magnus, on Weymouth pine. The disease generally makes its first appearance in roots and lower parts of the stem, spreading thence into higher parts. Diseased wood has a characteristic odour of turpentine; it has a reddish-brown colour, and, as destruction proceeds, it gradually shrinks and disintegrates till it becomes so soft as to be easily powdered between the fingers. Where broken over, the wood is often covered with a thin white coating of mycelium incrusted in resin so as to appear like chalk. The mycelium penetrates the cell-walls in all directions. A very characteristic feature of this parasite is furnished by shrinkage-fissures in the thick walls of the tracheids of the summer-wood (Fig. 280). These are numerous and run upwards from ricfht to left extending through the whole wall to the outermost layers. They differ from the fissures in tracheids destroyed by P. vaporarius, in that they run round the whole circumference of the cell, instead of being small and set vertically above each other. Polyporus (Fomes) pinicola (Sw.) ( America). Sporopliores thick, hoof-like or Viracket-shaped, with a smooth dark-grey upper side and a bright red rounded margin. The hymenial layer is smooth and yellowish, the spore-powder white. In section the sporophores are white. The species is frequent on living stems of spruce, pine, and fir, also on birch and cherry. Polyporus (Fomes) marginatus Fr. ( America). Sporo- phores with red margins, and otherwise very like those of the pre- ceding species, yet generally much l
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