222 Sargant and Arber.—Morphology of Gramineae . 
Fig. 2. Transverse section of coleoptile bundle from older seedling. Two groups of metaxylem 
(met., met.'), and scattered/.#, elements between them, x 250. 
Fig. 3. Transverse section of first node from same seedling as Fig. 2. Xylem of P and P r is 
branching : the outward branches will form xylem of sc/; the inward branches that of the coleoptile 
trace within the stele (x.). x 155. 
Fig. 4. Mesocctyl of same seedling a little below the first node. Traces M and x face each 
other in the stele ; they are bordered by a well-defined root-plate on either side. The inverted 
scutellum trace (sc/) is quite distinct from the stele, x 64. 
Fig. 5. Stele and scutellum trace more highly magnified a little below Fig. 4 in the same 
seedling. Scutellum trace with two distinct phloem groups, two groups of metaxylem, one of 
protoxylem. Root-plates very clear (rp., rp.) in stele, x 150. 
Zizania aquatica, L. 
Fig. 6. Drawing of seedling, life-size. A., grain; R., primary root; Ep., epiblast; PI., 
plumule ; col., coleoptile. The dotted line A.A. indicates level of Figs. 7 and 8. 
Fig. 7. Diagram of first node from seedling drawn in Fig. 6. The section is taken at level 
A.A. (Fig. 6). Lettering as in Avena. x 40. 
Fig. 8. Detail of the space enclosed by dotted lines in Fig. 7. Letters as before, x 240. 
PLATE X. 
Zizania aquatica, L. 
Fig. 9. Vascular girdle from older seedling. The coleoptile traces P and P' have not yet 
entered the stele. They are approaching it in direction indicated by arrows. Cauline root given off 
at r. x 66. 
Sorghum vulgare, Pers. 
Fig. 10. Mesocotyl of young seedling drawn in Text-fig. 20, p. 186. Transverse section a little 
above insertion of scutellum. x 260. px x ., protoxylem of scutellum trace within stele; px 2 ., 
protoxylem of downward coleoptile traces; px 3 ., protoxylem of M, which is midrib of first leaf; 
rx., rx., ‘ sentinel vessels ’ of root-xylem. 
Fig. 11. Coleoptile bundle from older seedling. Two phloem groups very distinct, x 320. 
Fig. 12. First node, from same seedling as Fig. 11. The xylem of the coleoptile bundles /*and 
P ' forms a bridge across the stele. Some thin-walled elements of large lumen appear at periphery 
of stele (root-xylem). x 75. 
Amomum angustifolium, Sonner. 
Fig. 13. Transverse section just above first node. P and P' are branching to meet cortical 
traces. The xylem girdle is nearly complete on one side; on the other there is an isolated cortical 
bundle (c.), which links up with the girdle a few sections lower in the series, x 190. 
Fig. 14. Hypocotylar stele of same seedling from same series, not far below first node. Large 
group of protoxylem, common to all the traces, in centre. The arrows ( m.r .) point to pathways of 
clear tissue dividing the traces, and partially bordered on either side by metaxylem. x 190. 
Tigridia Pringlei, S. Wats. 
Fig. 15. Transverse section through bundle of cotyledonary sheath in upper part of its course. 
It has doubled on itself, and its protoxylem is cut twice (px., px.), once going upwards, and a second 
time on its return. Lower down, the two segments separate. (Compare Text-fig. 8, p. 168.) x 260. 
