CONTENTS 



Page 



Preface vii 



CHAPTER I 



The Significance of Translocation and Earlier Opinions as to 



Tissues Involved 1 



1. The importance of translocation 1 



2. Older ideas as to tissues concerned in upward transfer .... 3 



3. Older ideas as to tissues concerned in downward transfer ... 6 

 Summary 11 



CHAPTER II 

 Evidence for the Upward Transport of Organic Matter through 



THE Phloem 12 



4. Ringing at different distances from the tip and the transport 



of carbohydrates previously stored in the xylem region . . 12 



5. Disappearance of starch below rings and results from double- 



ringing 14 



6. The disappearance of starch as a criterion of carbohydrate 



transport 17 



7. The effect of ringing on the transport of carbohydrate to 



growing shoots after that stored in the xylem is depleted . . 24 



8. The effect of ringing on transport to fruits 33 



9. The effect of cutting the xylem on the transport of solutes ... 36 

 Summary 45 



CHAPTER III 

 Evidence for the Upward Transport of Nitrogen and Salts 



through the Phloem 47 



10. Effects of ringing on the upward transfer of nitrogen and ash 



constituents 47 



11. Evidence tending to contradict that presented in sec. 10 ... 58 



12. Diurnal fluctuations in nitrogen and ash of leaves, indicating 



transport with the transpiration stream 64 



13. Relation of transpiration to solute absorption and movement 



in intact plants 70 



14. Absorption and transport under special conditions 77 



Summary 86 



CHAPTER IV 



Evidence Indicating Downward Transport through the Xylem 88 



15. Findings and interpretations of Birch-Hirschfeld 88 



16. Findings and interpretations of Dixon and his co-workers ... 94 



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