Fungi, Ascomycetes, Ustilaginales, Uredinales . *•£&& Bucholtz was able to examine, showed a system of internal chambers linedby the hymenium and communi-cating at one or more points withthe exterior. As development pro-ceeds these cavities increase in sizeand the hymenium becomes furtherconvoluted,so that additional cham-bers are formed. In Tuber the ascocarp is ir-regularly globose, fleshy or some-times almost woody; internally thewalls which divide the gleba areextensively branched, and the freespace between them is diminished,so that the layers of the hymeniumare brought close together and
Fungi, Ascomycetes, Ustilaginales, Uredinales . *•£&& Bucholtz was able to examine, showed a system of internal chambers linedby the hymenium and communi-cating at one or more points withthe exterior. As development pro-ceeds these cavities increase in sizeand the hymenium becomes furtherconvoluted,so that additional cham-bers are formed. In Tuber the ascocarp is ir-regularly globose, fleshy or some-times almost woody; internally thewalls which divide the gleba areextensively branched, and the freespace between them is diminished,so that the layers of the hymeniumare brought close together andconstitute the fertile veins. Otherveins, white and sterile, run be-tween the hymenial layers and serveas air chambers (fig. 97). The asciare often globose, and the sporesusually four in number, but thenumber varies, and is sometimesreduced to two or one (fig. 98). The development of the fruithas been studied by Bucholtz in. Tuber rufum Pico; section throughhymenium; after Tulasne. Tuber pubcrulum (fig. 99). The veryyoung ascocarp consists of a mass of hyphae, the outer rather more looselyinterwoven than the inner. Around the lower part a dense basal sheath isdifferentiated. Soon the first signs of the fertile veins appear as invagina-tions of the upper surface, and internally the loose tissue of the sterile veins1 01 nes recognizable. Owing to the rapid growth of the upper portion of the young fruit, thebasal sheath is bent backwards, while at various points along the fertile veinsthe first signs of asci appear. Later the peripheral tissues become thickened,together with the remains of the basal sheath, and form the peridium. Thisultimately closes over the points where the fertile veins are in communicationwith the exterior. Thus the young fruit is open at first, the hymeniumbecomes internal by imagination and the peridium which covers the matureascocarp is a secondary formation. The development of the f
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectfungi, bookyear1922
