204 Gibson,— -Contributions towards a Knowledge 
Fig. 44. S. sulcata , Spr. 
Trabecular tissue and inner cortex ( X350). 
Figs. 45-48, 50. S. Kraus siana , A. Br. 
Fig. 45. Plan of arrangement of steles. A = axis, B — branch. 
Fig. 46. Inner cortex, trabeculae and stele ( x 550). 
Figs. 47-48. Endodermal cells enclosed by common cuticular rings ( x 550). In 
Fig. 47 the cuticle is continued up the endodermal cells from the pericycle. 
Fig. 50. Trabecular tissue, wholly or partially cuticularized, at the angles between 
the forking of steles ( x 550). 
Fig. 49. S. rubella , Moore. 
Silicified intercellular space in cortex ( x 350). 
Figs. 51-55. S. inaequalifolia , Spr. 
Fig. 51. Transverse section of the erect stem ( x 50'. a, epidermis ; hypo- 
dermis ; c, cortex ; d, silicified layers of the inner cortex ; e, lacuna between the 
ventral and ventral- accessory steles, containing completely cuticularized trabecular 
cells ; fj pericycle ; g, phloem ; h , phloem-parenchyma ; z, protoxylem ; /, 
metaxylem. 
Fig. 52. The dorsal and dorsal-accessory steles of Fig. 51 in transverse section 
( x 550). a , inner cortex; b, silicified cortical cells ; c, pericycle ; d, protophloem ; 
e, sieve-tubes ; f phloem parenchyma ; g , protoxylem ; h , completely cuticularized 
cells in the lacuna between the steles. 
Fig. 53. Longitudinal section (semi-diag.) of the stem showing the distribution 
of the steles at a forking of the stem. The section ends abruptly in the angle 
between the branch and the axis, a , dorsal, b, dorsal accessory, c, median, d, 
ventral, e, ventral accessory steles ; f leaf-trace from axillary leaf ; g, stele to the 
dorsal, and h , to the ventral rhizophore ( x 20). 
Fig. 54. Plan of the arrangement of the steles in an erect shoot, seen from 
above. The steles have been turned somewhat out of their normal position to 
right and left in order to make it more easy to follow their course. The dotted 
lines indicate the borders of the ventral stele. 
Fig. 55. Lacuna and trabeculae in longitudinal section ( x 3 = 0). 
Figs. 56-58. S. Wallichii, Spr. 
Trabeculae and lacunar parenchyma ( x 550). 
PLATE XI. 
Figs. 59-60. S. Wallichii, Spr. 
Fig. 59. Transverse section of half the ventral stele (x55o\ a , pericycle; 
b, protophloem ; c, sieve-tubes ; d, phloem-parenchyma ; e, metaxylem ; f proto- 
xylem. 
Fig. 60. Apex of a primary erect shoot dissected to show arrangement of leaf- 
traces and protoxylems. 
Figs. 61-62. S. Willdenowii, Bak. 
Fig. 61. The serial sections I-VII illustrate the mode of fusion of the steles at 
the origin of a branch. The sections are taken from above, downwards. 
Fig. 62. Fragmentation of the steles in a section of an old stem (x 30). 
