. Fossil plants : for students of botany and geology . Paleobotany. 460 COENOPTERIDEAE [CH. antennae. The crushed tissue lying on the outer face of each of the loops probably represents the phloem and pericycle; the thin-walled elements above and below the horizontal band of metaxylem are probably sieve-tubes. Fig. 316 shows a transverse section of a petiole of this species: the loops, a, of small tracheae are seen bending round the outer edge of the antennae. The inner and more delicate cortical tissue is partially preserved and spaces, b, have been formed in it as the result of contraction p
. Fossil plants : for students of botany and geology . Paleobotany. 460 COENOPTERIDEAE [CH. antennae. The crushed tissue lying on the outer face of each of the loops probably represents the phloem and pericycle; the thin-walled elements above and below the horizontal band of metaxylem are probably sieve-tubes. Fig. 316 shows a transverse section of a petiole of this species: the loops, a, of small tracheae are seen bending round the outer edge of the antennae. The inner and more delicate cortical tissue is partially preserved and spaces, b, have been formed in it as the result of contraction previous to Fig. 317. Ankyropteris corrugata. From a section in the Cambridge Botany School Collection. ( x 9.) In the petiole represented in fig. 317 the tracheae of the horizontal band are considerably crushed; the section is, how- ever, of interest because of the presence of Lyginodendron roots, I, in the space originally occupied by the inner cortex! In a paper on the tyloses of Jiachiopteris corrugata, Weiss^ draws attention to the fact that similar inclusions have not been found in the tracheae of recent ferns. The occurrence of thin-walled parenchymatous cells in the large tracheae of Ankyropteris corrugata petioles and of other species is a striking feature. Williamson ^ compared these cells with the tyloses in the vessels of recent flowering plants, and in a later paper s he suggested that the included cells may belong to saprophytic or parasitic fungi. It is, as Weiss points out, 1 Weiss, F. E. (06). 2 WiUiamson (77). s Williamson (88) 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 Seward, A. C. (Albert Charles), 1863-1941. Cambridge : University Press
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