. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. EMBRYOLOGY 357 with the mode of development of these parts in mature plants. For the variability in haustorial development within the genus the study of the embryology of Lycopodium has already prepared the way. Both genera demonstrate the inconstancy of the haustorial organs of the embryo, and justify my conclusion of more than twenty years ago, that these swellings. A A Fig. 190. Embryos of Selaginella spinulosa. A-D illustrate the segmentation. I. I., first wall, separating the suspensor ; IV. IV.,
. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. EMBRYOLOGY 357 with the mode of development of these parts in mature plants. For the variability in haustorial development within the genus the study of the embryology of Lycopodium has already prepared the way. Both genera demonstrate the inconstancy of the haustorial organs of the embryo, and justify my conclusion of more than twenty years ago, that these swellings. A A Fig. 190. Embryos of Selaginella spinulosa. A-D illustrate the segmentation. I. I., first wall, separating the suspensor ; IV. IV., corresponds to wall similarly marked in Figs. 183, 186, and to wall t>, b in Fig. 182; ^=wall marking off the vascular strand of the axis. Ki K^—cotyledons ; £ = ligule ; W=root. E — section of germinated spore with embryo in still. G, Ar=seedlings. H, natural size ; G, enlarged. 7?=the basal knot enlarged ; i?£=s\ispensor ; Wj W%=Toots. (After Bruchmann.) of the hypocotyl arise when and where they are required, and are not to be held to be clearly defined or constant morphological In both of the points named it would seem probable that S. spinulosa represents a more primitive type than S. Martensii. Comparing this embryogeny with that of Lycopodium, it seems remark- able that the similarity of detail should be so great when the difference 1 Quart, foiirn. Micr. Sa'., xxii., p. 292, 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 Bower, F. O. (Frederick Orpen), 1855-1948. London, Macmillan and Co. , Ltd.
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