ORGANIZATION OF THE FOSSIL PLANTS OF THE COAL-MEASURES. 957 
have been formed. The parenchymatous cells at the corners of the trachez 
are shown. The wood is surrounded by secondary cortical tissues, probably 
including both phloém and periderm. At ¢, ¢, remains of the primary cortex 
are present, but only a part of this has been drawn. O.N. 897. xX 30. 
Fig. 41. Part of an oblique section, showing a portion of the primary xylem. In the 
direction of the arrow (px) is a group of protoxylem, with spiral trache, 
partly uncoiled. Adjoining these below are scalariform trachexw, and below 
these again are pitted elements. Above the protoxylem a small portion of 
the secondary wood is indicated. C.N. 893. x 200. 
Fig. 42. Part of an approximately transverse section, to show secondary wood, 2’; 
cambium, cb; and phloém, ph. C.N. 882. x 70. 
Fig. 43. Part of a transverse section (the same as that shown in photograph 19 on 
Plate 75); «, part of primary xylem; x*, secondary xylem; cb, cambium ; 
ph, phloém ; pd, internal periderm. C.N. 894. x 50. 
Fig. 44. Part of a radial section through the secondary wood, showing the radially- 
elongated parenchymatous cells (as at r), passing between the trachee. 
C.N. 884. x 50. 
Fig. 444. Part of another, approximately radia] section, showing the longitudinal 
strands of xylem-parenchyma, #.p., x.p., and portions of the radial cells 
connecting them. C.N. 903. xX 50. 
Figs. 45 and 46. Sphenophyllum insigne. 
Fig. 45. Approximately transverse section of a young stem, without any secondary 
thickening. In the middle is the triarch primary xylem, with protoxylem at 
the three angles. Surrounding this are the primary cortical tissues. O.N. 
911. X 50. 
Fig. 46. Transverse section of a very young stem, showing part of a whorl of 
coherent leaves, in which two foliar vascular bundles are seen (v.b.). The 
fragments of tissue seen to the exterior are probably portions of leaves. 
st = stele of stem. C.N. 917. xX 50. 
PLATE 84. 
Sphenophyllum insigne. 
Fig. 47. A. Longitudinal median section, passing through a node. J, J, bases of 
leaves. xX 13. 
B. Portion of wood from the same preparation, seen in tangential, but 
somewhat oblique section. The scalariform markings of the trachez, and the 
medullary rays (7) are seen. Cf. fig. 50. C.N, 1420. x 100. 
