. Lichens. Lichens. 46 CONSTITUENTS OF THE LICHEN THALLUS II. LICHEN HYPHAE A. Origin of Hyphae Lichen hyphae form the ground tissue of the thallus apart from the gonidia or algal cells. They are septate branched filaments of single cell rows and are colourless or may be tinged by pigments or lichen acids to some shade of yellow, brown or black. They are of fungal nature, and are produced by the mature lichen spore. The germination of the spore was probably first observed by Meyer^ His account of the actual process is somewhat vague, and he misinterpreted the subsequent development into thallu
. Lichens. Lichens. 46 CONSTITUENTS OF THE LICHEN THALLUS II. LICHEN HYPHAE A. Origin of Hyphae Lichen hyphae form the ground tissue of the thallus apart from the gonidia or algal cells. They are septate branched filaments of single cell rows and are colourless or may be tinged by pigments or lichen acids to some shade of yellow, brown or black. They are of fungal nature, and are produced by the mature lichen spore. The germination of the spore was probably first observed by Meyer^ His account of the actual process is somewhat vague, and he misinterpreted the subsequent development into thallus and fruit entirely for want of the necessary magnification; but that he did succeed in germinating the spores is unquestionable. He cultivated them on a smooth surface and they grew into a "dendritic formation"—a true hypothallus. Many years later the development of hyphae from lichen spores was observed by HoUe^ who saw and figured the process unmistakably in Borrera {Pkyscid) ciliaris. A series of spore cultures was undertaken by Tulasne^ with the twofold object of discovering the exact origin of hyphae and gonidia and of their relationship to each other. The results of his classical experiment with the spores of Verrucaria muralis—as interpreted by him—were accepted by the lichenologists of that time as conclusive evidence of the genetic origin of the gonidia within the thallus. The spores of the lichen in large numbers had been sown by Tulasne in early spring on the smooth polished surface of a piece of limestone, and. Fig. 14. Germinating spores of Verrucaria muralis Ach. after two months' culture x ca. 500 (after Tulasne). were covered with a watch-glass to protect them from dust, etc. At irregular intervals they were moistened with water, and from time to time 1 Meyer 1825. 2 Holle 1849. 3 Tulasne Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance
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