. Carnegie Institution of Washington publication. Fig. 32.— Three sections of an older embryo of Botrychium virginianum, cut transverse to long axis of embryo. bb, basal wall; /, f^ot; r, root; rf,stemapex; eo/, cotyledon. 200. In B. virginianum traits of the quadrant formation are still evident at a com- paratively latr stage, and there seems no reason to doubt the correctness of Jeffrey's conclusion as to the epibasal origin of both the root and the cotyledon. As in Ophtoglossum pendulum and (). vulgatum, the root is especially conspicuous and reaches a large size, while tin stem apex and co
. Carnegie Institution of Washington publication. Fig. 32.— Three sections of an older embryo of Botrychium virginianum, cut transverse to long axis of embryo. bb, basal wall; /, f^ot; r, root; rf,stemapex; eo/, cotyledon. 200. In B. virginianum traits of the quadrant formation are still evident at a com- paratively latr stage, and there seems no reason to doubt the correctness of Jeffrey's conclusion as to the epibasal origin of both the root and the cotyledon. As in Ophtoglossum pendulum and (). vulgatum, the root is especially conspicuous and reaches a large size, while tin stem apex and cotyledon are still inconspicuous. Indeed, in B. lunaria, according to Bruchmann, no trace ol either stem apex or D >i vlcdoti can he made out until the root has broken through the calyptra. At this stage ( fig. 36, C, D) the embi vo of 11. lunaria bears a striking resem- blance to that of Ophto- glossum vulgatum. It was found bv Jef- 111 \ m B. virginianum that the stem initial was developed before the co- tyledon could be seen, but I have failed to verify this in the specimens I have examined. Fig. ^2 shows three sections of a series taken from an embryo of about the age of [effrey's fig. I his embryo wascut transversely to its long axis, and the root apex is thus seen in cross-section. I he root here probably comprises the whole of one of the epibasal quadrants, from the other of which, or from part of it, perhaps a single octant, the stem apex and cotyledon arise in close proximity. It is probable that part of this quadrant goes to form the "suspensor," or that epibasal tissue which is not concerned in the formation of the young organs of the embryo. Fig. .ji, II shows a section passing through the young cotyledon, whose single apical cell is already differentiated. This in section is triangular, and the cell is probably of tetrahedral shape. Fig. }2, C, shows the section passing through the stem It'.;, I '' ium virginianum, cut in the ('Line of the
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Keywords: ., bookauthorcarnegie, bookcentury1900, bookdecade1910, bookyear1911
