Griffin.— Development of Neiv Zealand Conifer Leaves. 71 



To sum up in a few words : the development of the successive 

 stages of Conifer leaves is, to a very great extent, merely the 

 acquisition in the mature leaves of better appliances for the 

 manufacture of food, and for its protection during the processes 

 of assimilation. 



EXPLANATION OF PLATES VIII-X. 



Lettering used in Figures. 



cut. Cuticle. peric. Pericycle. 



epid. Epidermis. t.t. Transfusion tissue. 



hyp. Hypoderm. p. ph. Protophloem. 



l.sur.par. Lower surface parenchyma. ph. Phloem. 



upp.sur.par. Upper surface parenchyma. x. Xylem. 



e.par. Elongated parenchyma. px. Protoxylem. 



acc.t.t. Accessory transfusion tissue. cpx. Centripetal xylem. 



t.s. Tannin-sac. scler. Sclerenchyma. 



end. Endodermis. r.c. Resin-canal. 



The following are transverse sections, unless otherwise stated: — 



Plate VIII. 



Fig. 1. Vascular bundle, youngest stage ; totara cotyledon, x 192. 



Fig. 2. Vascular bundle, apex, young cotyledon ; totara. x 192. 



Fig. 3. Vascular bundle, older cotyledon, x 192. 



Fig. 4. End of young cotyledon, x 192. 



Fig. 5. Vasculav bundle, youngest leaf, x 192. 



Fig. 6. Tangential section, young cotyledon; totara. x 192. 



Fig. 7. Outlines, transverse section — (a) cotyledon ; (6) young leaf, x 12. 



Fig. 8. Vascular bundle, older totara-leaf. x 192. 



Fig. 9. Radial longitudinal section through outer elements transfusion 



tissue ; shrub ; totara. x 100. 

 Fig. 10. Transverse section, showing transitions in size of transfusion 



tracheids from px to endodermis ; shrub ; totara. x 100. 

 Fig. 11. Middle elements ; older leaf, totara. x 100. 

 Fig. 12. End of mature leaf, totara. x 100. 

 Fig. 13. Outlines, transverse section — (a) mature totara ; (b) mature 



miro ; (c) youngest leaf ; (d) cotyledon (miro). x 12. 



Plate IX. 



Fig. 14. Bundle of cotyledon; miro. x 164. 



Fig. 15. End of cotyledon ; miro. x 100. 



Fig. 16. Tangential section, bundle, cotyledon; miro. x 164. 



Fig. 17. Bundle, older leaf, miro, stage 1. x 164. 



Fig. 18. Bundle, stage 2 ; miro. x 164. 



Fig. 19. Radial longitudinal section transfusion tissue ; mature miro. 

 X164. 



Fig. 20. Awl-shaped leaf, stage 1 ; kahikatea. x 100. 



Fig. 21. Flattened leaf, stage 1 ; kahikatea. x 100. 



Fig. 22. Bundle, awl-shaped leaf, second year ; kahikatea. x 192. 



Fig. 23. Bundle, flattened leaf, second year ; kahikatea. x 192. ^ 



Fig. 24. Outlines, transverse sections — (a) cotyledon ; (6) stage 1, awl- 

 shaped ; (c) stage 1, flattened form ; (d) leaf, awl-shaped, 

 on plant three years old ; (e) flattened form on three-year-old 

 plant ; (/, g, h) different mature forms ; kahikatea. x 22. 



