The result of the activity of this cambium band is the production of secondary parenchyma and tracheal tissue. In fig. 179, E, drawn from a portion of the section represented in fig. 168, B, a projecting arm of primary xylem is seen at _x_; this is followed by 2–3 layers of parenchymatous cells, some of which have dark contents, and beyond this is seen a group of secondary elements, _tr_, cut across somewhat obliquely, which are evidently products of the cambial cells on the inner margin of the secretory zone, _sc_. The longitudinal section (fig. 169, D) shows the cambial cells, a, next the secretory zone, _sc_, passing internally into crushed and imperfectly preserved elongated elements which are presumably miniature tracheae, and these are succeeded by older and more completely lignified xylem elements, _x_. In larger shoots the amount of secondary tissue is considerably greater; it may consist almost entirely of short-celled parenchyma (fig. 168, C, from _x_ to _sc_), or it may include a large proportion of radially disposed and vertically elongated tracheae (fig. 168, D, _x_², and fig. 170, A, _x_²), or it may consist of parenchyma containing scattered groups of tracheae (fig. 169, A, _x_²)[326]. [Illustration: FIG. 169. _Lepidodendron fuliginosum._ A, B. (Manchester University Collection. No. Q. 645 A.) B, C. (Manchester. No. 257.) D. (Manchester. No. 6.)] Fig. 169, A, is a diagrammatic sketch of the tissues—1 mm. wide—between the primary xylem, _x_, and the inner cortex. The primary xylem is succeeded by short parenchymatous cells followed by a zone of radially elongated elements passing occasionally into rows of narrow scalariform tracheae, some of which, owing to their sinuous longitudinal course (fig. 171, C), are seen in oblique section, as at C, fig. 169, A. At its outer edge this secondary tissue, _x_², consisting of parenchyma and tracheae, passes into the cambial band (fig. 169, B, _a_). [Illustration: FIG. 170. _Lepidodendron fuliginosum._ (From sections in the Manchester Museum.)]