678 
DR R. KIDSTON AND PROF. W. H. LANG ON OLD RED SANDSTONE PLANTS 
Plate VIII. 
Fig. 58. Transverse section of small shoot with the differentiation of tissues uncompleted. 1., leaf ; o.c., 
outer cortex ; middle layer of inner cortex ; i.c.i., inner layer of inner cortex ; s., undifferentiated stele, 
x 60. (No. 2486.) 
Fig. 59. Transverse section of stem in a region behind the. apex where the differentiation of the stelar 
tissues has just begun, x 10. (No. 2454.) 
Fig. 60. Transverse section of the stele of the section below that shown in fig. 59. The poles of the 
developing stem-xylem are marked x. ; the other dark groups of elements are leaf-traces, x 60. 
(No. 2473.) 
Fig. 61. Epidermis of two adjacent stems showing the thick outer wall and cuticle, x 105.# (No. 2486.) 
Fig. 62. Epidermis (ep.) and outer cortex (o.c.) from the transverse section of a small stem, x 105. 
(No. 2486.) 
Fig. 63. Longitudinal section of stem, o.c., outer cortex; i.c.o., outer zone of inner cortex; i.c.m., 
middle (trabecular) zone of inner cortex; i.c.i., inner zone of inner cortex; x., xylem. x 14. (No. 2494.) 
Fig. 64. Oblique section of stem showing the complete course of a leaf-trace ( l.t .) from the neighbourhood 
of the stele to a leaf-base. x 14. (No. 2495.) 
Fig. 65. Stoma in surface view and adjoining epidermal cell% with contracted dark contents, x 210. 
(No. 2491.) 
Fig. 66. Stoma in vertical section across the pore, x 210. (No. 2496.) 
Plate IX. 
Fig. 67. The inner cortex in transverse section showing the middle (trabecular) zone well preserved. 
i.c.o., outer zone ; i.c.m., middle zone ; i.c.i., inner zone, x 33. (No. 2475.) 
Fig. 68. Well-preserved inner zone of the inner cortex {i.c.i.). i.c.m., middle (trabecular) zone. x 33. 
(No. 2497.) 
Fig. 69. Transverse section of stele showing distinct layer of cells ( en .) in the position of an 
endodermis. x 33. (No. 2506.) 
Fig. 70. Longitudinal section of partially-preserved phloem (ph.) of stem, x., xylem; i.c.i., inner zone 
of inner cortex. x 60. (No. 2498.) 
Fig. 71. Portion of middle zone of inner cortex not clearly trabecular but showing the cells and the 
intercellular spaces well. x 105. (No. 2497.) 
Fig. 72. Transverse section of stele of stem with exceptionally well-preserved phloem (ph.). x., xylem; 
i.c.i., inner zone of inner cortex. x 33. (No. 2475.) 
Fig. 73. Portion of the epidermis of stem in the transition region in surface view showing stomata with 
large pores, x 210. (No. 2471.) 
Plate X. 
Figs. 74-76. Ends of the rays of stellate xylem from the same stele in transverse section showing the 
structure of the tracheides. px., groups of small elements of the protoxylem. x 105. (No. 2499.) 
Figs. 77-79. Longitudinal sections of the xylem of the stem showing the structure of the tracheides. 
px., narrow elements of protoxylem. x 210. (Fig. 77, No. 2500; Figs. 78, 79, No. 2492.) 
Fig. 80. Large leaf-trace in transverse section showing the Central protoxylem. x 210. (No. 2500.) 
Fig. 81. Similar leaf-trace beside an arm of the stem xylem with its immersed protoxylem. x 210. - 
(No. 2501.) 
Fig. 82. Small leaf-trace separating from an arm of the xylem in which the protoxylem is less evident, 
x 210. (No. 2501.) 
Plate XI. 
Fig. 83. Transverse section of stele from same stem as fig. 51 showing a branch-trace ( hr . tr.) preparing 
to separate from one ray of the xylem. x 33. (No. 2483.) 
