CONTENTS XV 



26. Effects of Light and Temperature on Plant Growth 



Frits W. Went 557 



27. The Origin and Growth of Plant Communities 



Pierre Dansereaii 567 



28. The Origin of the Plant Tumor Cell 



Armin C. Braun 605 



29. Growth Aspects of Plant Virus Infections 



Glenn S. Pound 621 



30. The Biological Environment of Roots 



A.G. Norman 653 



31. Plant Root-Soil Interactions 



Hans Jenny 665 



32. Transport Processes in the Soil-Plant System 



Morell B. Russell and Joseph T. Woolley 695 



33. Colloid Chemistry of the Soil in Relation to Plant Nutrition 



C. Edmund Marshall 723 



Glossary '' 737 



Index 745 



