Fungous diseases of plants . ha, and a septum isformed at a distance of severalmicromillimeters from thepoint of origin of the hyphae may be almosthyaline when young, but verygenerally become yellowishbrown with age. Furthermore,in age the branches appear tobe more at right angles, atleast, so far as the origin isconcerned. Upon many hostplants, and especially when thefungus is grown in pure cul-tures, a short tufted growth ofthe mycelium may occur. Thehyphae of these tufts are brown,closely septate, constricted atthe septa, and often branchedin an irregular dichotomousfashion (Fig.
Fungous diseases of plants . ha, and a septum isformed at a distance of severalmicromillimeters from thepoint of origin of the hyphae may be almosthyaline when young, but verygenerally become yellowishbrown with age. Furthermore,in age the branches appear tobe more at right angles, atleast, so far as the origin isconcerned. Upon many hostplants, and especially when thefungus is grown in pure cul-tures, a short tufted growth ofthe mycelium may occur. Thehyphae of these tufts are brown,closely septate, constricted atthe septa, and often branchedin an irregular dichotomousfashion (Fig. 222, /;). In thelatter case the hyphae readilybreak up into short hyphal lengths, consisting of a single cell ormore, and these cells are able to germinate within a few hourswhen placed in fresh nutrient media. Germination is commonlyby means of a germ tube protruded from a septum. A germ tubemay even, in some cases, pass through a neighboring cell. It wouldappear that the fruiting stage usually develops upon living I-k;. 22\. RlllZoCTliNIA ()\ 1>K.\N Stems and Puds. (Photograph byH. H. Whetzel) AUTOBASIDIOMYCETES 451 In the case of the potato, it forms a membranous layer inclos-ing the stem for several inches above the surface of the layer is composed of rather loosely interwoven hyphae, andon account of this character it is difficult to say if the plant isproperly placed under the genus Corticium, or whether it mightnot with equal propriety be considered a species of basidia are short, cylindrical, or oblong, and apparently many
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