. Textbook of botany. Botany. A MUSHROOM 77. pink if broken. The gills are at first flesh-colored or pink, gradually changing, as the fruiting body grows older, to dark brown or black. The stalk is white, and from two to four inches high. 105. Structure of the Fruiting Body. — In a thin section of the stalk, examined under a low power of the microscope, one sees many cells of diflFerent shapes. From the way in which the fruiting body has been developed, we know that these are the cells of the separate threads that make up the fruiting body, cut across in various ways. Such a structure as this,
. Textbook of botany. Botany. A MUSHROOM 77. pink if broken. The gills are at first flesh-colored or pink, gradually changing, as the fruiting body grows older, to dark brown or black. The stalk is white, and from two to four inches high. 105. Structure of the Fruiting Body. — In a thin section of the stalk, examined under a low power of the microscope, one sees many cells of diflFerent shapes. From the way in which the fruiting body has been developed, we know that these are the cells of the separate threads that make up the fruiting body, cut across in various ways. Such a structure as this, composed of threads closely packed together, is sometimes called a false tissue, to dis- tinguish it from the true tissues which make up the bodies of the higher plants. The cap of the mushroom is composed likewise of a false tissue. A section through the cap which cuts a gill crosswise shows how the spores are formed (Fig. 35). Each surface of the gill is made up of a layer of rather long cells that are perpendicu- lar to the surface. Some of the ceUs of this layer are rather slender; others, when they reach their fuU size, are much broader. Each of the broad cells of the surface layer is a, basidium. From the end of each basidium four slender projections grow out; the outer end of each projection swells and is cut ofi by a wall, so becoming a spore.' 106. Distribution and Germination of Spores. — When the spores are ripe they are shot oflf from the short stalks on which they were borne. This shooting seems to be caused by a sudden bulging of the wall at the end of each stalk. By this means the spores are thrown far enough so that they may fall -ndthout touching any of the neighboring basidia. Being 1 In some cultivated varieties (perhaps all) of the field mushroom, and occaaon- ally in wild races, each basidium forms only two projections and two spores. u3ym B Fig. 35. — A, section through a gUI, showing the arrangement of threads and basidia. B, a group of basidia of
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1917
