. Fungi, ascomycetes, ustilaginales, uredinales. Fungi. IV] TUBERALES 137 Bucholtz was able to examine, showed a system of internal chambers lined by the hymenium and communi- cating at one or more points with the exterior. As development pro- ceeds these cavities increase in size and the hymenium becomes further convoluted, so that additional cham- bers are formed. In Tuber the ascocarp is ir- regularly globose, fleshy or some- times almost woody; internally the walls which divide the gleba are extensively branched, and the free space between them is diminished, so that the layers of the hyme
. Fungi, ascomycetes, ustilaginales, uredinales. Fungi. IV] TUBERALES 137 Bucholtz was able to examine, showed a system of internal chambers lined by the hymenium and communi- cating at one or more points with the exterior. As development pro- ceeds these cavities increase in size and the hymenium becomes further convoluted, so that additional cham- bers are formed. In Tuber the ascocarp is ir- regularly globose, fleshy or some- times almost woody; internally the walls which divide the gleba are extensively branched, and the free space between them is diminished, so that the layers of the hymenium are brought close together and constitute the fertile "; Other "veins," white and sterile, run be- tween the hymenial layers and serve as air chambers (fig. 97). The asci are often globose, and the spores usually four in number, but the number varies, and is sometimes reduced to two or one (fig. 98). The development of the fruit has been studied by Bucholtz in. Tuber rufum Pico; section througli hymenium; after Tulasne. Tuber piiberuluni (fig. 99). The very young ascocarp consists of a mass of hyphae, the outer rather more loosely interwoven than the inner. Around the lower part a dense basal sheath is differentiated. Soon the first signs of the fertile veins appear as invagina- tions of the upper surface, and internally the loose tissue of the sterile veins becomes recognizable. Owing to the rapid growth of the upper portion of the young fruit, the basal sheath is bent backwards, while at various points along the fertile veins the first signs of asci appear. Later the peripheral tissues become thickened, together with the remains of the basal sheath, and form the peridium. This ultimately closes over the points where the fertile veins are in communication with the exterior. Thus the young fruit is open at first, the hymenium becomes internal by invagination and the peridium which covers the mature ascocarp is a secondary formation. The developmen
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectfungi, bookyear1922
