. A textbook of botany for colleges and universities ... Botany. Fig. 386. — Leaflet of Marattia, showing dichotomous venation and synangia (instead of sori). band of thick-walled cells which extends from the stomium over the top of the capsule and down on the other side to the stalk (figs. 385, 39°)- The primary sporogenous cell cuts off a sterile cell from each one of the four faces, these four cells developing the tapetum (figs. 388, 389). The centrally placed sporoge- nous cell then be- gins a series of divisions until 16 mother cells are formed, which means a maximum output of 64 spores.
. A textbook of botany for colleges and universities ... Botany. Fig. 386. — Leaflet of Marattia, showing dichotomous venation and synangia (instead of sori). band of thick-walled cells which extends from the stomium over the top of the capsule and down on the other side to the stalk (figs. 385, 39°)- The primary sporogenous cell cuts off a sterile cell from each one of the four faces, these four cells developing the tapetum (figs. 388, 389). The centrally placed sporoge- nous cell then be- gins a series of divisions until 16 mother cells are formed, which means a maximum output of 64 spores. Sometimes. Figs. 387-389.—Sporangium of one of the Polypodiaceae: 387, early stage, in which the outer papillate cell has begun to form the apical cell; 388 later stage, in which the cap cell and upper segments invest a central cell (primary spermatogenous), which has cut off one tapetal cell; 389, later stage, in which all there are only 8, the tapetal cells have been cut oft'and have begun to divide; the pvpn central cell, by a series of divisions, forms 16 mother cells. ' mother cells. The tapetal cells break down, leaving the mother cells free in the enlarged cavity (fig. 390). These two kinds of sporangia, one from each extremity of the fern series, indicate not only a passage from the eusporangiate to the lepto- sporangiate habit, but also a striking reduction in the output of spores per sporangium. In this latter feature there is complete intergrading through the intermediate 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 Coulter, John Merle, 1851-1928; Barnes, Charles Reid, 1858-1910, joint author; Cowles, Henry Chandler, 1869- joint author. New York, Cincinnati [etc] American book company
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1910
