424 Hill and Freeman. — Dioscorea prehensilis. 
EXPLANATION OF FIGURES IN PLATE XIX. 
Illustrating Mr. Hill’s and Mrs. W. G. Freeman’s paper on Dioscorea prehensilis. 
Abbreviations: end., endodermis ; p.c ., passage cell; ph ., phloem; ph.s., 
phloem-strand ; xy., xylem. 
Fig. i. Portion of a large spine-bearing root. 
Fig. 2. Illustrating the development of the large vessels in the inner regions 
of the vascular cylinder of a large spine-bearing root. 
Fig. 3. Part of a transverse section of a similar but older root, showing the 
highly lignified tissue external to a phloem-group. 
Fig. 4. Similar section from an older root. 
Fig. 5. Diagram of a transverse section of one of the smaller absorbent roots. 
Fig. 6. Portion of Fig. 5 in detail. 
Fig. 7. Diagram, showing origin of a large spine. 
Fig. 8. Diagrammatic transverse section near the base of a spine, showing 
the disposition of the phloem and xylem. 
Fig. 9. Diagrams of a series of transverse sections of a spine, illustrating 
the gradual fusion of the phloem, from the base (a) to the apex (e); stele only 
represented. 
Fig. 10. Diagram of a transverse section of the vascular cylinder of an immature 
spine. 
Fig. 11. Transverse section of part of the stele of an older spine, but still 
not fully developed. 
