. Carnegie Institution of Washington publication. THE OLDER SPOROPHYTE 181 at an earlier period. The mucilage ducts throughout the life of the sporophyte are less conspicuous in Kaulfussia than in Dance a. A section taken at the level of the stem apex in the very young sporophyte (fig. 137) presents an appearance not unlike that found in the bud in Ophioglossum. The base of the cotyledon extends around the stem apex, so that in the section the stem apex and the second leaf are inclosed in this cavity formed by the stipular sheath of the cotyledon. Higher up, the base of the cotyledon becomes f
. Carnegie Institution of Washington publication. THE OLDER SPOROPHYTE 181 at an earlier period. The mucilage ducts throughout the life of the sporophyte are less conspicuous in Kaulfussia than in Dance a. A section taken at the level of the stem apex in the very young sporophyte (fig. 137) presents an appearance not unlike that found in the bud in Ophioglossum. The base of the cotyledon extends around the stem apex, so that in the section the stem apex and the second leaf are inclosed in this cavity formed by the stipular sheath of the cotyledon. Higher up, the base of the cotyledon becomes free from the second leaf, but this takes place earlier on one side than on the other. The development of the vascular system in the stem is exactly as it is in Dancea. The stem apex in the young sporophyte takes no part in the development of the vascular bundles, the stele in the stem being made up entirely of the united leaf traces. In the specimen figured (fig. 164), in which the second leaf was still quite young, the bundle from the cotyledon passes downward into the stem and continues its downward course until it joins the second leaf trace. The resulting solid stele at first shows the two separated xylems of the component leaf traces which lower down merge into a single thick band of xylem completely surrounded by the phloem. Fk;. 1C5.—Three longitudinal sections of a young sporophyte of Kaulfussia, with three leaves. X25. (fig. 164, EH). This stage corresponds to Brebner's "haplostele" in Dancea sim- plicifoha. This condition merges insensibly into the primary root with its diarch bundle, the two xylems in the younger part of the root being quite separate, but forming a single band at the base of the transitional region, between the root and the bundle in the stem. The bundle of the root shows a conspicuous endodermis which becomes less and less evident in the transitional region, although it prob- ably never quite disappears. The primary root usually shows th
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