. L'anatomie comparée des organes végétatifs des phanérogames marines et de fougères ;. Anatomie végétale ; Fougères. 564 Les modifications secondaires. Pruiius Cerasus, Ligustrum vulgare, Syringa persica, Salix fragilis, Rhus toxicodendron typhinum, Fraxinus ornus, Robinia pseudacacia, et beaucoup d'autres ;-ou, le cas les stomates sont regroupés, un lenticel se forme, dans chaque groupe, p. ex. espèces de Populus" Juglans regia, Hedera et Regnoriana ; la stomie en vertu de laquelle le lenticel vient se trouve au milieu de celle-ci à un stade ultérieur de développement, tandis que d'autres voisins ceux bouring réside peut-être dans la périphérie, p. ex. Euonymus europ

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. Comparative anatomy of the vegetative organs of the phanerogams and ferns;. Plant anatomy; Ferns. 564 SECONDARy CHANGES. Pruiius Cerasus, Ligustrum vulgare, Syringa persica, Salix fragilis, Rhus typhinum, Fraxinus Ornus, Robinia pseudacacia, and many others;—or, where the stomata are grouped together, one lenticel is formed under each group, e.g. species of Populus» Juglans regia, and Hedera Regnoriana; the stoma under which the lenticel originates lies over the middle of the latter at a later stage of development, while other neigh- bouring ones may lie in the periphery, e.g. Euonymus europseus, Persica vulgaris, and Cornus sanguinea. Even where the stomata are less numerous, some of them may remain with- out any share in the formation of lenticels, as is especially conspiteuous: in the horizontal shoots to be described below, in which the number of lenticels on the upper side is smaller than that on the lower side. In the investigated cases the stomata are here equally numerous on both sides, and on the upper side at least are always more numerous on the same area than the lenticels. The formation of lenticels below stomata begiris with the growth and divisions of the parenchymatous cells lying in this position. (Figs. 222, and 223, comp. also Fig. 221, p. 560). The divisions at first take place variously in different directions. Their products, and also no doubt the cells which have not yet divided, grow chiefly in the direction at right. FIG. 222, —Transverse section through a young internode of a branch of Betula alba (375). e—e epidermis; a respiratory cavity under a stoma; c the cuticle, which is separated from e as far as the entrance of the pore by a layer of secretion (removed by alcohol). At x the first beginnings of the divisions which give rise to the complementary tissue.. 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

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