XV Contents 



'"Copper 41 



Molybdenum 45 



The Importance of Molybdenum in the Fixation of 



Gaseous Nitrogen 47 



References 50 



Discussion 50 



^ On the EflFect of Copper and Manganese on the Iron 

 Status of Higher Plants hy Jorma Erkama, Ph.D. (Bio- 

 chemical Institute of the University, Helsinki, Finland) 53 



Some Aspects of the Occurrence of Copper, Manganese, 



AND Iron in Plants 54 



Effect of Copper and Manganese on Iron Uptake . . 55 



Discussion of Results 56 



References 59 



Discussion 60 



Injury Through Excess of Manganese hy M. P. Lohnis, 

 Ph.D. (Laboratorium voor Microbiologie der Landbouw- 



hogeschool, Wageningen, Netherlands) 63 



Preparation of the Experimental Plots 63 



Disease Symptoms of Phaseolus vulgaris 64 



Manganese Content of Healthy and Affected Foliage of 



Phaseolus vulgaris 64 



Experiments with Other Plants 67 



Determination of Exchangeable Manganese in Soil . . 69 



Experiments with Vicia sativa 74 



References 75 



Discussion 75 



The Action of Manganese on Roots hy H. Burstrom, 

 Fil.Dr. (Botanical Laboratory of the University, Lund, 



Svi^eden) 77 



Action of Manganese on the Morphological Develop- 

 ment OF Roots 77 



Action of Nitrate 78 



Combined Action of Manganese and Nitrate on Excised 



Roots 80 



Interaction of Iron and Manganese on Cell Length . . 81 



Discussion 82 



Zinc Deficiency of Fruit Trees in Europe hy D. Mulder, 



Ph.D. (Wilhelminadorp, Zeeland, Netherlands) ... 85 



Symptoms on Apples in Holland 85 



In Other Parts of Europe 85 



Other Fruit Trees 86 



