iqo8] DORETY—CERATOZAMIA 219 



17. , On the origin of transfusion tissue in the leaves of gymnospermous 



plants. Jour. Linn. Soc. 33:118. 1897. 



18. , Comparative anatomy of the Cycadaceae. Jour. Linn. Soc. 33:437. 



1898. 



19. , The anatomical structure of Bowenia spectabilis Hook. Annals of 



Botany 14:159. 1900. 



EXPLANATION OF PLATES XII-XVI 



All the drawings except figs. 6-1 1, 16, 21-25 were made with the aid of a 

 camera lucida. The abbreviations used are as follows: A, B, C, D, the four 

 main cotyledonary bundles; An, Bn, Cn, Dn, the corresponding root poles; 

 C, median bundle of developed cotyledon; D, median bundle of aborted one; 

 a, a', lateral bundles of aborted cotyledon; b, b', lateral bundles of developed 

 one; ad, adaxial face of cotyledon; c, cotyledon; cb, cambium; cb', cb" , extra- 

 fascicular cambium; cl, coleorhiza; ct, connective tissue of root; ex, cortex; cfx, 

 centrifugal xylem; cpx, centripetal xylem; d, d! ', lateral traces of first leaf; e, ef , 

 middle traces of same; /, foliar bundles; Z 1 ,/ 2 ,/ 3 ,/ 4 , four principal groups of 

 foliar bundles; g, cotyledonary trace; h, vascular system of hypocotyl; i, vas- 

 cular system of root; imd, initiation of mucilage duct; j, sclerenchyma; k, root 

 cap; /, leaf; m, meristematic plate; md, mucilage duct; 11, medulla; 0, indices 

 of radial cell division in medulla; p, plumule; ph, phloem; pph, protophloem; 

 px, protoxylem; pxf , rupture of tissues caused byprotoxylem; q, plerome; r, root; 

 s, suspensor; t, leaf trace; tr, transfusion tissue; u, stem bundles; v, periblem; 

 w, stipules; x, xylem; y, cork; z, anomalous thickening. 



Figs. 1-5. — Stages in intraseminal development showing single lateral 

 cotyledon and gradual enlargement of its base to encompass axis. X5. 



Fig. 6. — Rupture of micropylar end of seed coat and protrusion of base of 

 embryo. X$. 



Fig. 7. — Bending of base of embryo and exit of plumule. Xi 



Fig. 8. — Appearance of root. X§. 



Figs. 9, 10. — Young seedlings. XJ. 



Fig. 10a. — Longitudinal section through tip of unfolding leaf. X5. 



Fig. 11. — Dissection of aerial portion of two-year-old seedling. Nat. size. 



Fig. 12. — Diagram showing spiral phyllotaxy of later leaves. Nat. size. 



Fig. 13. — Transverse section of cotyledon. X8. 



Fig. 13a. — Transverse section of cotyledons of embryo developed on clinostat. 

 X8. 



Fig. 14. — Transverse section of upper portion of cotyledon showing tendency 

 to lobe. X8. 



Fig. 15. — Transverse section of same cotyledon nearer tip. X8. 



Fig. 16. — Diagram to show venation of cotyledon. 



Fig 17. — Mesarch bundle from lower portion of cotyledon. X380. 



Fig. 18. — Exarch bundle from the middle region of cotyledon. X380. 



