378 BOTANICAL GAZETTE [NOVEMBER 
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a 
EXPLANATION OF PLATES XXIII-XXIX 
PLATE XXIII 
Fic. 1—Embryo in mature seed: cot, cotyledon; sh, tubular sheath of 
cotyledons; st, stem proper; r, hypocotyl; s, suspensor. ' 
Fic. 2.—Cross-section of embryo just above stem tip: cof, tubular part 0 
colytedons; Ly, first leaf; Li, L?, L3, L4, vascular strands of first leaf; L., second 
leaf; L3, Li, 3, L4, vascular strands of second leaf; L;, third leaf. a 
1G. 3.—Median longitudinal section of lower part of embryo, parallel wi 
inner faces of cotyledons: cot, cotyledon; L;, La, first and second leaves; S 
pinna; /s, foliar strand; st, stem tip; , pith; cs, cotyledonary strand; vp, vas 
cular plate; /, plerome; cp, caplike tissue; sp, suspensor. 
1G. eee cemeat aco, of part of vascular system rs 
embryo; cof, cotyledon; #b, tubular part of cotyledons; cs, cotyledonary stran®» 
Li—Li, foliar strands of first leaf; Li—L4, foliar strands of second leaf; * 
vascular plate; a, protoxylem elements continuing downward into the hypocoty- 
Fic. 4a.—Cross-section of a vascular bundle in upper extremity of saute 
leaf; x, xylem elements; a, cells losing their contents during lignification; i 
Procambium; pph, protophloem; 6, line showing boundary between protoxylem 
and protophloem. 
PLATE XXIV si ol 
Fic. 5.—Semi-diagrammatic reconstruction of part of vascular ef yes; 
embryo, to show especially the girdling: Lx, L», traces of first and second ie ne 
vp, vascular plate; px, protoxylem groups; a, xylem elements continuing 
from protoxylem groups to form the protoxylem of the primary root. ocigi 
Fic. 6.—Diagram giving bird’s-eye view of vascular system, t0 ae 
and girdling of foliar strands: cot, tubular part of cotyledons; cotyl | 
traces, one group for each cotyledon; L,, Lz, L3, L,4, first, seco 
ss ee 7 ES L3, L4, traces of first leaf; Li, L3, La, 4» 
Second leaf; px, protoxylem groups. 
Fic. 7.—Outline of ieee just above stem tip of seedling three °F <e 
years old, to show phyllotaxy; cot, cotyledons; 1-8, leaves in order of si () 
Fic. 7a (1).—Stem tip from germinating embryo with leaf 
developing on the side. 
