§ 3. Relation of the Stomata to Gaseous Exchange. § 4. Distribution and Dimensions of Stomata. § 5. Diffusion through the Stomata. § 6. Stomatal Movements and their Mechanism. § 7. Gaseous Exchange of Aquatics. § 8. Gaseous Exchange of Succulents. § 9, Energy Relations of Assimilation. § 10. Orientation of the Leaf and Illumination. § 11. Mechanism of Leaf Adjustment. § 12. Orientation of Strongly Insolated Leaves. § 13. Leaf Structure and Assimilation. § 14. Chlorophyll and Absorption of Light. § 15. Chlorophyll in its Relation to Assimilation. § 16. E.xternal Conditions and Assimilation. § 17. Assimilation in Natural Environment. § 18. Extent of Transpiration. § 19. Water Balance, Wilting, and Water Storage. § 20. Atmospheric Conditions and