. The structure and development of mosses and ferns (Archegoniatae). Fig, 199.—Three sections of one embryo of O. cinnamomea in which the root (r) isespecially well marked, X260. Lettering as in the last. The direction of growth of the cotyledon is determined inpart by the first walls in its primary octants. The outer octantusually becomes at once its apical cell, and if its first segmentis formed on the side next the octant wall, this throws the axisof growth very much to one side, so that the axis of the leafmay be almost at right angles to the median line of the ^ise it nearly
. The structure and development of mosses and ferns (Archegoniatae). Fig, 199.—Three sections of one embryo of O. cinnamomea in which the root (r) isespecially well marked, X260. Lettering as in the last. The direction of growth of the cotyledon is determined inpart by the first walls in its primary octants. The outer octantusually becomes at once its apical cell, and if its first segmentis formed on the side next the octant wall, this throws the axisof growth very much to one side, so that the axis of the leafmay be almost at right angles to the median line of the ^ise it nearly coincides with this. The original three-sided apical cell persists for a long time, and it could not bepositively shown whether or not it was afterwards replaced by; 358 MOSSES AND FERNS CHAP. a two-sided one. The further development of the cotyledoncorresponds almost exactly with Onoclea. It does not break. Fig. 200.—A, Horizontal section of an advanced embryo of 0. Claytoniana, passingthrough the cotyledon and foot, X230; B, longitudinal section of the stem apexin a somewhat older embryo of O. cinnamomea, X460; C, transverse section ofthe apex of the primary root of the same, X460. through the calyptra until later, and in this respect shows itsprimitive character. The single vascular bundle of the petiole
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Keywords: ., bookauthorcampbelldouglashought, bookcentury1900, bookdecade1910
