Xylems in the Petioles of Cycads. 
193 
Literature cited. 
1. Bertrand, C. Eg,, et Renault, B. : Remarques sur les faisceaux foliaires des Cycadees 
actuelles. Arch. Bot. du N. de la France, 1886. 
2. Carano, E. : Contribuzione alia conoscenza della morfologia e dello sviluppo del fascio 
vascolare delle foglie delle 4 Cicadacee’. Annali di Botanica, Roma, 1903. 
3. Chodat, R. : ( a ) Sur quelques fossiles vegetaux. Bulletin de PHerbier Boissier, 2 e serie, 
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vol. vii, 1861, pp. 565-608. 
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8. Sprecher, A.: Le Ginkgo Biloba. Geneve, 1907. 
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EXPLANATION OF PLATE XI. 
Illustrating Dr. Le Goc’s paper on Centripetal and Centrifugal Xylem in the Petioles of Cycads. 
Fig. 1. Cycas circinalis , four years old, base of petiole, a compound structure, clb = collateral 
bundle ; ccb = concentric bundle ; px = protoxylem ; cfx — centrifugal xylem ; ph — phloem ; 
mr — medullary ray. 
Fig. 2. C. revoluta^ two years old, base of petiole, clb — collateral bundle. 
Fig. 3. C. revoluta , base of petiole, ccb = concentric bundle. 
Fig. 4. C. circinalis , near base, cpx = centripetal xylem. 
Fig. 5. C. circinalis , present year, base of petiole 40 cm. long. 
Fig. 6. C. revoluta , present year, base of petiole 10 cm. long. 
Fig. 7. Encephalartos horridus , near base ; cpx and cfx separate. 
Fig. 8. Stangeria paradoxa, near base ; cpx and cfx separate. 
Fig. 9. Cycas circinalis , near base; cpx independent. 
Fig. 10. C. circinalis , far from base ; cfx separate from px and cfx. 
Fig. 11. C. circinalis , far from base. Longitudinal section showing different forms of tracheides. 
Fig. 12. C. circinalis , wound structure, secondary cpx. 
Fig. 13. Large bundle of transfusion tissue {tfb). 
O 
