202 Gibson. — Contributions towards a Knowledge 
Fig. 4. Bifurcate endodermal cell from the point of origin of a branch ( x 800). 
Fig. 5. Cuticular annulus seen from above, a , before, b, after isolation of the 
ring from the pericyclar cuticle ( x 800). 
Figs. 6-7. S. grandis, Moore. 
Fig. 6. Transverse section of the median part of the stele, a , a , pericycle ; b> b , 
sieve-tubes; c, c, phloem-parenchyma ; centrally, metaxylem (x8oo). 
Fig. 7. Lacuna and trabecular tissue ( x 800). 
Fig. 8. S. Vogelii , Spr. 
Longitudinal section through the pericycle and trabecular tissue ( x 800). 
Fig. 9. S. I \aematodes , Spr. 
Transverse section through the pericycle, trabecular tissue and inner cortex ; 
the dark shading indicates siliceous deposit ( x 800). 
Fig. 10. S. erythropus , Spr. 
Strongly sclerotised fibres of the outer cortex of the creeping axis in transverse 
section ( x 550). 
Fig. 11. .S'. Griffithii , Spr. 
Transverse section of the margin of the stele, showing a single layer of sieve- 
tubes surrounding the protoxylem ( x 800). 
Figs. 12-13. S. viticulosa , Kl. 
Fig. 12. Longitudinal section of the stem showing twisted trabecular cells 
( x 55 °) • 
Fig. 13- Chloroplastids from the trabecular cells (x 800). 
Figs. 14-15. S. serpens , Spr. 
Fig. 14. Transverse section of the stem (semi-diagrammatic), a, hypodermis ; 
b, inner cortex ; c , c, leaf-traces of dorsal leaves ; d, d, leaf-traces of ventral leaves ; 
e, lacuna round leaf-trace ; f lacuna round stele ; g> pericycle ; h, sieve-tube layer ; 
i, phloem-parenchyma ; k, metaxylem ; /, marginal protoxylem ; m, dorsal cord 
(X30). 
Fig. 15. Trabecula from the origin of a branch ( x 550). 
Fig. 16. S. molliceps, Spr. 
Transverse section of the stele showing irregularity of the pericycle and small 
amount of phloem ( X550). 
Fig. 17. S. involvens, Spr. 
Portion of the inner cortex in section. The dark shading indicates Si 0 2 
( X550). 
Fig. 18. S.patu/a, Spr. 
Transverse section of a small portion of the stele and inner cortex ( x 550). 
Figs. 19-20. S.flabellata, Spr. 
Fig. 19. Portion of the stele dissected out and viewed from the dorsal side, 
showing the arrangement of the dorsal cords ( x 10). 
Fig. 20. The stele in transverse section ; the irregular dark outer line represents 
the siliceous deposit on the inner cortex, a, pericycle; b, sieve-tube layer; 
c, phloem-parenchyma ; d, one of the dorsal protoxylems ( x 30). 
Fig. 21. S. atroviridis, Spr. 
Scheme of arrangement of protoxylems in the stele ( x 10). 
