. Comparative morphology of Fungi. Fungi. 202 COMPARATIVE MORPHOLOGY OF FUNGI by the special structure of the perithecial rind. Before the rind has completed its peridial structure, some of its cells develop to long append- ages; these are generally characteristic and offer one of the most conven- ient points for the separation of genera. In Erysiphe, Leveillula (Fig. 127) and Sphaerotheca, they are simple, hyphal-like and intertwined with the mycelium; in Podosphaera (Fig. 128, 4) and Microsphaera (Fig. 128, 1 to 3), they are repeatedly dichotomously branched at the tips; in Uncinula (Fig. 12
. Comparative morphology of Fungi. Fungi. 202 COMPARATIVE MORPHOLOGY OF FUNGI by the special structure of the perithecial rind. Before the rind has completed its peridial structure, some of its cells develop to long append- ages; these are generally characteristic and offer one of the most conven- ient points for the separation of genera. In Erysiphe, Leveillula (Fig. 127) and Sphaerotheca, they are simple, hyphal-like and intertwined with the mycelium; in Podosphaera (Fig. 128, 4) and Microsphaera (Fig. 128, 1 to 3), they are repeatedly dichotomously branched at the tips; in Uncinula (Fig. 128, 5 to 7), they are coiled more or less spirally at the tips; in Typhulochaeta, they are clavate and arranged in a ring consisting of. Fig. 127.—Leveillula taurica. Section through the lower surface of a leaf and the peridium of a perithecium, showing extra- and intramatrical mycelium and the hyphal appendages. (X 400; after Arnaud, 1921.) two or three rows around the top of the perithecium; and in Phyllactinia, unbranched, but setiform and rigid, with a saccate base (Fig. 129, 1). As regards the structure of perithecial wall, there are two groups. In Sphaerotheca, Erysiphe (Fig. 125, 2) and Leveillula, the rind (as in the Plectascales) is spread approximately evenly over the whole fructifica- tion; in Microsphaera and Uncinula, it possesses a dorsiventral structure consisting generally at the base of wide-lumened, thin-walled cells and at the top of narrow-lumened, thick-walled cells. Neger (1901, 1902) attempts to interpret these observations biologically as follows: in the first group, with the peridium symmetrical on all sides, the perithecia are generally sessile. Their appendages are interwoven with mycelium and. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Gäumann, Ernst Albert, 1893-1963; Dodg
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