Beyond the most recently formed tracheae we have a band of delicate parenchymatous cells (_m_, figs. B and E, 181; C, figs. 183, 184) forming the meristematic zone[359]. The longitudinal section represented in fig. 184 shows some recently formed narrow tracheae, T, and beyond these the meristematic zone composed of thin-walled short cells, C, arranged in horizontal rows. It is this small-celled tissue to which the name phloem has been applied by some authors[360], a term which seems to me to be misleading and inappropriate. In passing through this zone of dividing cells the leaf-traces become surrounded by an arc of meristem from which elements are added to the radially placed rows of secondary tracheae. Beyond the meristematic region portions of the secretory zone are preserved, consisting of large sacs or spaces and small dark cells as seen in figs. 181, B, E, _sc_, F; 183, 184. This tissue has the same structure as in _L. vasculare_ and in _L. fuliginosum_: it is a striking fact that there are no indications of any additions to the secretory zone even in stems with such a large amount of secondary xylem as in the Dalmeny specimen (fig. 182, _x_²). If the secretory zone were of the nature of phloem we should expect to see signs of additions made to it in the course of growth. In this connexion it is worth mentioning that in the recent fern _Botrychium_ (Ophioglossaceae) secondary xylem is formed in the stem, but apparently no additions are made to the phloem. The structure of the secretory zone tissue as seen in the longitudinal section fig. 184, S, is also a serious difficulty in the way of accepting the designation phloem as employed by Scott and Weiss. Between the secretory zone and the outer cortical region, no tissues have been preserved. The shell of bark consists chiefly of radial rows of elongated cells with rather thick walls characterised by the occurrence of small intercellular spaces and by tangentially placed bands of secretory cells and sacs (fig. 181, D, _s_). Immediately internal to the secondary cortex or phelloderm occur groups of secretory tissue as shown in the section of _L. Harcourtii_ (fig. 179, B). [Illustration: FIG. 183. _Lepidodendron Wünschianum._ From the specimen shown in fig. 181, S, secretory zone; C, meristem; T, immature tracheae.] [Illustration: FIG. 184. _Lepidodendron Wünschianum._ Longitudinal section of the specimen represented in transverse section in fig. 183.]