. An introduction to the structure and reproduction of plants. Plant anatomy; Plants. BACTERIA 261 as usually, this takes place on a large scale, the surface of the thallus acquires a powdery appearance. The individual granules (so-called soredia, Fig. 142, A), being distributed by the wind, afford a rapid means of propagation of the Lichen. The bright colours of many Lichens are due to the presence of pigments which are remarkable for their " fast " character, and have been employed in dyeing. The well-known chemical indicator litmus is obtained from species of Roccella. Iceland Mos
. An introduction to the structure and reproduction of plants. Plant anatomy; Plants. BACTERIA 261 as usually, this takes place on a large scale, the surface of the thallus acquires a powdery appearance. The individual granules (so-called soredia, Fig. 142, A), being distributed by the wind, afford a rapid means of propagation of the Lichen. The bright colours of many Lichens are due to the presence of pigments which are remarkable for their " fast " character, and have been employed in dyeing. The well-known chemical indicator litmus is obtained from species of Roccella. Iceland Moss {Cetraria islandica. Fig. 143), which forms a slimy fluid when boiled with water, is used as an jr-a invalid food. ..tM*k\^ The Bacteria con- stitute an extremely important group of Thallophyta whose re- lationships are very obscure. The majority of species are colour- less unicellular plants of extremely small size. The larger speci- mens are not more than i/iooth mm. in length and about one- tenth as wide, whilst the globular forms average i/ioooth mm. in diameter. Some are so small as to be almost, if not quite, invisible under the highest powers of the microscope. They occur in almost every possible situation, and live under the most varied conditions. They are not killed by cold, and some can survive for many months at the temperature of liquid air. Whilst most die if heated to about 50° C, a few (thermophilic Bacteria) live in fermenting hay and manure heaps which, owing to their activity, may attain a temperature of 70° C.^ Many Bacteria also in- habit the waters of hot springs. 1 Hence the employment of manure for hot-beds, et?,. Fig. 143.—Iceland Moss (Cetraria islandica), part of a large specimen, about natural 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 Fritsch, Felix Eugene, 1879
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectpl, booksubjectplants
