. Text-book of botany, morphological and physiological. Botany. TILICINEM. 479 sporangia, the inner ones only microsporangia, the former containing a large number of macrospores. Both kinds of sporangia are imperfectly chambered by bands of tissue {trabecules) which cross from the ventral to the dorsal side. The sporangia do not dehisce, but the spores escape by the decay of the wall. In the Selaginellece the sporangia are shortly stalked roundish capsules. The macrosporangia contain usually four, less often two or eight macrospores. In the division of Articulatse the lowermost sporangium only
. Text-book of botany, morphological and physiological. Botany. TILICINEM. 479 sporangia, the inner ones only microsporangia, the former containing a large number of macrospores. Both kinds of sporangia are imperfectly chambered by bands of tissue {trabecules) which cross from the ventral to the dorsal side. The sporangia do not dehisce, but the spores escape by the decay of the wall. In the Selaginellece the sporangia are shortly stalked roundish capsules. The macrosporangia contain usually four, less often two or eight macrospores. In the division of Articulatse the lowermost sporangium only of a spike produces macror spores; in the other divisions there are several macrosporangia. The sporangia do not take origin, as Hofmeister's older accounts would seem to show, from single cells. FIG. 337,—Development of the sporangia and spores of Selaginella inaqualifolia*, the order of succession is indicated by the letters A—D; A and B serve for all the sporangia, C and D for the microsporangia only ; E division of the mother- cells of the microspores, h four nearly ripe spores; in A, C and D, a, b are the two layers of the wall of the sporangium, c is the tapetum, d the primary mother-cells of the spores (A, B and E X 500; C and D x 200). of the epidermis, but, as in Lycopodzum, from a group of such cells (according to Goebel1). The sporangia arise on the growing-point of the stem immediately above the base of the corresponding leaves, but this by no means justifies us in regarding them as cauline organs as Russow does. Like those of Lycopodium, they at first appear as flattened protuberances which become more or less spheroidal at a later period and finally clavate. At a later period the sporangia appear to be inserted in the axil of the leaves or on their base. The fibro-vascular bundle of the leaf runs 1 [Beit. z. Vergl. Entwick. d. Sporangien; Bot. Zeitg. 1881.]. Please note that these images are extracted from scanned page images that may have been digitally enha
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1882
