378 BOTANICAL GAZETTE [November 



3. Lestiboudois, Th., Memoire sur la structure des Cycadees. Compt. Rend. 

 51:651-655. i860. 



4. Mettenius, G., Beitrage zur Anatomie der Cycadeen. Abhandl. Kgl. 

 Sachs. Gesells. Wiss. 5:565-608. pis. i-j. 1861. 



5. Bertrand, C. Eg., et Renault B., Remarques sur les faisceaux foliaires des 

 Cycadees actuelles et sur la signification morphologique des tissues des 

 faisceaux unipolaires diploxyles. Arch. Bot. Nord. France 2:232-242. 1886. 

 (Rev. Compt. Rend. 102:1184-1187. 1886.) 



6. Matte, Henri, Recherches sur 1'appafeil liberoligneux des Cycadacees. 

 Caen. 1904. 



EXPLANATION OF PLATES XXIII-XXIX 



PLATE XXIII 



Fig. i. — Embryo in mature seed: cot, cotyledon; sh, tubular sheath of 

 cotyledons; st, stem proper; r, hypocotyl; s, suspensor. 



Fig. 2. — Cross-section of embryo just above stem tip: cot, tubular part of 

 colytedons; L x , first leaf; L\, L\, L\, Li, vascular strands of first leaf; L 2 , second 

 leaf; LI, LI, LI, Li, vascular strands of second leaf; L a , third leaf. 



Fig. 3. — Median longitudinal section of lower part of embryo, parallel with 

 inner faces of cotyledons: cot, cotyledon; L z , L 2 , first and second leaves; pn, 

 pinna; Is, foliar strand; st, stem tip; p, pith; cs, cotyledonary strand; vp, vas- 

 cular plate; pi, plerome; cp, caplike tissue; sp, suspensor. 



Fig. 4. — Semi-diagrammatic reconstruction of part of vascular system of 

 embryo; cot, cotyledon; tb, tubular part of cotyledons; cs, cotyledonary strands; 

 L\ — L\, foliar strands of first leaf; L\—L\, foliar strands of second leaf; vp, 

 vascular plate; a, protoxylem elements continuing downward into the hypocotyl. 



Fig. 4a. — Cross-section of a vascular bundle in upper extremity of young 

 leaf; x, xylem elements; a, cells losing their contents during lignification; pc, 

 procambium; pph, protophloem; b, line showing boundary between protoxylem 

 and protophloem. 



PLATE XXIV 



Fig. 5. — Semi-diagrammatic reconstruction of part of vascular system of 

 embryo, to show especially the girdling: £,, L 2 , traces of first and second leaves; 

 vp, vascular plate; px, protoxylem groups; a, xylem elements continuing down 

 from protoxylem groups to form the protoxylem of the primary root. 



Fig. 6. — Diagram giving bird's-eye view of vascular system, to show origin 

 and girdling of foliar strands: cot, tubular part of cotyledons; cs, cotyledonary 

 traces, one group for each cotyledon; L s , L 2 , L 3 , L 4 , first, second, third, and 

 fourth leaves; L\, L\, L\, L\, traces of first leaf; L\, L\, L\, L\, traces of 

 second leaf; px, protoxylem groups. 



Fig. 7. — Outline of cross-section just above stem tip of seedling three or four 

 years old, to show phyllotaxy; cot, cotyledons; 1-8, leaves in order of age. 



Fig. ya (1). — Stem tip from germinating embryo with leaf primordium (L) 

 developing on the side. 



