Modern Methods of Plant Analysis / Moderne Methoden der Pflanzenanalyse

- Contents.- Emission and Atomic Absorption Spectrochemical Methods..- A. Flame Emission Methods.- I. Lundegardh Method.- II. Flame Photometric Method for Sodium, Potassium and Calcium.- III. Flame Spectrophotometric Method for Magnesium.- IV. Flame Spectrophotometric Method for Iron, Manganese and Copper.- B. Arc Emission Analysis.- I. The Variable Internal Standard, Cathode Layer Method.- II. Direct Cathode Layer Analysis of Plant Ash.- III. The Method of Successive Additions.- C. Spark Emission Methods.- I. Porous Cup Solution Spark Method for Magnesium.- II. The Pelleted Rotating Disc Spark Method.- D. Atomic Absorption Methods.- References.- Mass Spectrometric Methods..- A. Instrumentation.- B. The Sample.- I. Vapor Pressure.- II. Techniques of Introduction.- III. Purity.- C. Origin of Mass Spectra and their Interpretation.- I. Ionization and Fragmentation of Organic Molecules.- II. The Molecular Weight.- III. Simple Fragments.- IV. Rearrangements.- V. Metastable Ions.- VI. Multiple-Charged Peaks.- VII. Mixtures.- VIII. High Resolution Spectra.- D. Specific Applications.- I. Amino Acids.- 1. Qualitative Spectra.- 2. Quantitative Analysis of Amino Acid Mixtures.- II. Amino Acid Sequence in Peptides.- III. Fatty Acids and Related Compounds.- IV. Alkaloids.- V. Miscellaneous Groups.- VI. Determination of Stable Isotopes in the Intact Molecule.- Appendix I.- References.- Plant Spectra: Absorption and Action..- A. Instrumentation.- B. Light Scatter Phenomena.- C. Absorption Spectra.- D. Action Spectra.- E. Fluorescence Excitation Spectra.- References.- Gefriertrocknung..- A. Die biologischen Probleme der Gefriertrocknung.- I. Das intracellular Gefrieren.- II. Die Vitrifikation.- III. Das extracelluläre Gefrieren.- IV. Die Trocknung.- V. Die Fehlerquellen.- VI. Testmethoden.- B. Die Vakuum-Sublimation.- I. Theoretische Grundlagen.- II. Apparative Ausrüstung.- 1. Der Vakuum-Pumpstand.- 2. Der Trocknungsraum.- 3. Kühleinrichtungen.- 4. Objektheizung.- 5. Meßgeräte.- III. Gefriertrocknungsanlagen.- C. Anwendungen.- I. Gefriertrocknung flüssiger Präparate.- II. Konservierung von Mikroorganismen.- III. Fixation für cytochemische Untersuchungen.- IV. Fixation für elektronenoptische Untersuchungen.- D. Verwandte Methoden.- I. Gefrierkonservierung.- II. Gefriersubstitution.- III. Gefrierschnitte.- Vapour Phase Chromatography..- A. Theoretical Approach.- I. Chromatography in General.- 1. Nature of Stationary Phase: Adsorption vs. Partition.- 2. Mobile Gas Phase : Elution, Displacement and Frontal Analyses.- II. Types of Theories.- 1. Linear vs. Non-Linear Distribution Isotherms.- 2. Ideal vs. Non-Ideal Chromatography.- III. Plate Theory.- 1. Calculation of the Number of Theoretical Plates.- 2. Calculation of the Distribution Coefficient.- 3. Evaluation of a Chromatographic Separation.- IV. Rate Theory.- 1. Eddy Diffusion.- 2. Molecular Diffusion.- 3. Resistance to Mass Transfer.- 4. Temperature, Flow Rate and Pressure.- V. Modifications and Additional Theories.- B. Apparatus Requirements.- I. Detection Systems.- 1. Integral Methods.- a) Titration.- b) Electrical Conductivity.- c) Volume and Pressure Changes.- d) Combustion to Carbon Dioxide.- 2. Differential Detectors - which Consume the Sample.- a) Combustion to Carbon Dioxyde.- b) Hydrogenation to Methane.- c) Flame Emissivity.- d) Hydrogen Flame and Thermocouple.- e) Flame Ionization.- 3. Differential Detectors - which Preserve the Sample.- a) Surface Potential.- b) Dielectric Constant.- c) Impedance of Gas Flow.- d) Heat of Vaporization.- e) Interferometer.- f) Spectroscopy.- g) Radioactivity.- h) Thermal Conductivity - the Katharometer or Diapharometer.- i) Gas Density Balance.- j) High Voltage Ionization.- k) Thermionic Emission.- 1) ? -Ray Ionization.- m) Radio Frequency Detector.- 4. Summary of Detector Characteristics.- II. Gas Phase.- III. Sample Introduction.- 1. Gaseous Samples.- 2. Solid and Liquid Samples.- IV. Stationary Phase.- 1. Column Construction.- 2. Column Dimensions.- 3. Capillary Columns.- 4. Solid Support.- 5. "Active" Solid Adsorbents.- a) Charcoal, Alumina Silica Gel.- b) Molecular Sieves.- c) Tailing Reducers.- d) Chromatothermography.- e) Multiple Columns.- 6. Liquid Phase for GLC.- a) Column Preparation.- b) Selection of the Stationary Phase.- c) Improvement of Peak Symmetry.- V. Temperature Control.- 1. Types of Heating Units.- 2. Programmed Temperature Chromatography.- C. Techniques.- I. Sample Preparation.- 1. Removal of Water.- 2. Esterification.- II. Fraction Collection.- III. Sample Identification.- 1. Use of Standards.- 2. Homologous Series Plots.- 3. Detectors with Different Responses.- 4. Auxiliary Instruments.- 5. Electron Affinity Spetroscopy.- 6. Functional Group Classification.- IV. Quantitative Analysis.- 1. Peak Heights.- 2. Peak Areas.- 3. Overlapping Peaks.- 4. Sloping Base Line and Secondary Peaks.- 5. Instrument Correction Factors.- 6. Internal Standard and Internal Normalization.- D. Applications.- I. Analytic Applications.- 1. Carbon Dioxide and Oxygen : Respiration and Photosynthesis.- 2. Hydrogen, Hydrogen Sulfide, Methane and other Fermentation Gases.- 3. Olefins and Saturated Hydrocarbons.- 4. Nitrogen, Nitrous Oxide, Nitrogen Dioxide and Nitric Oxide.- 5. Ammonia, Organic Amines and Amino Acids.- 6. Alkaloids, Indoles, Purines and Related Compounds.- 7. Carbohydrates.- 8. Lipids, Fatty Acids.- 9. Mono and Dicarboxylic Acids of Low Molecular Weight, and their Derivatives.- 10. Alcohols, Aldehydes, Ketones and Miscellaneous Esters.- 11. Phenyl Propanoid Compounds, Aromatic Acids, Phenols and Related Substances.- 12. Terpenes.- 13. Sulfur Compounds.- 14. Steroids.- 15. Miscellaneous Compounds.- II. Preparative Gas Chromatography.- E. Conclusion.- References.- Ion-Exchange Chromatography..- A. Ion-Exchange Materials.- I. Fundamental Properties of Ion-Exchange Resins.- 1. Chemical Structure.- 2. Physical Properties.- a) Cross-Linking.- b) Exchange Capacity.- c) Particle Size.- II. Ion-Exchange Celluloses.- B. Theory of Chromatographic Procedures.- I. Elution Analysis.- 1. Theory of Elution Analysis.- 2. Conditions for Successful Elution Analysis on Ion-Exchange Resins.- II. Displacement Development.- 1. Completely Ionized Components.- 2. Incompletely Ionized Components.- Comparison of Elution and Displacement Methods.- III. Frontal Analysis.- C. Apparatus.- D. Experimental Procedures.- I. Purification of Ion-Exchange Resins.- II. Preparation of the Column.- III. Operation of the Column.- 1. Elution Analysis.- a) Column Loading.- b) Choice of Solvents.- c) Selection of Temperature.- d) Analysis of Effluent.- e) Regeneration of Ion-Exchangers.- 2. Displacement Development.- a) Selection of Column Size.- b) Concentration of Developer.- c) Size of Fraction.- d) Regeneration of Resins.- E. Some Applications of Ion-Exchange Chromatography.- I. De-Ionization and Preliminary Group Separation of Extracts from Plant Tissues.- Separation into Four Groups.- a) Aromatic Substances.- b) Cationic or Basic Groups.- c) Acidic Substances.- d) Neutral Substances.- II. Separation of a Group of Closely Related Solutes by the Elution Method.- III. Separation of Compounds of High Molecular Weight.- F. Ion-Exclusion.- G. Mechanism of Adsorption of Solutes on Ion-Exchange Resins.- H. Applicability of Ion-Exchange Chromatography.- I. Choice of Ion-Exchanger.- II. Conditions for Chromatography.- III. Rechromatography.- References.- Table 1. Chromatographie grade resins and celluloses.- Molecular Sieving other than Dialysis..- A. Ion-Exchange Materials as Ionic Sieves.- Separations by Ionic Sieving.- B. Molecular Sieving on Starch.- C. Dextran Gels as Molecular Sieves.- 1. Theory of gel Filtration.- 2. Preparation and Operating of Columns.- 3. Some Applications of Dextran Gels as Molecular Sieves.- References.- Dünnschicht-Chromatographie..- A. Methode und Geräte.- I. Die Herstellung dünner Sorptionsschichten.- II. Sorptionsmittel und Bereitung der Streichmasse.- 1. Kieselgel G für Dünnschicht-Chromatographie "Merck".- 2. Aluminiumoxid G für Dünnschicht-Chromatographie "Merck".- 3. Kieselgur G für Dünnschicht-Chromatographie "Merck".- III. Auftragen der Substanzen und Auswahl des Elutionsmittels.- IV. Trennkammer und deren Sättigungszustand.- V. Sichtbarmachung der getrennten Substanzen.- 1. Chemische Verfahren.- 2. Physikalische Verfahren.- a) Aktivitätsmessung.- b) Fluorescenzverfahren.- 3. Biologische Verfahren.- VI. Untere Erfassungsgrenze im Vergleich zur Papierchromatographie.- VII. Dokumentation und allgemeine Auswertung.- VIII. Quantitative Auswertung.- 1. Direkte Verfahren.- 2. Indirekte Verfahren.- B. Spezielle Arbeitstechniken.- I. Zirkular- und Formgebungstechnik.- II. Stufentechnik.- III. Zweidimensionale Arbeitsweise ohne und mit Zwischenreaktion.- C. Anwendungsbereich und Einsatzmöglichkeiten.- D. Anwendungsbeispiele.- 1. Alkaloide.- 2. Aminosäuren.- 3. Indol-Auxine.- 4. Steroide und Steroidglykoside.- 5. Lipide.- Literatur.- Paper Chromatography on a Preparative Scale..- A. General.- I. Impurities.- II. Choice of Solvent System.- III. Quantities.- IV. Application of the Sample.- V. Localisation of Bands.- VI. Elution of the Resolved Spots.- B. Multisheet- and Cardboard-Chromatography.- C. Separation on Paper-Packs.- I. Circular Chromatopack Procedure.- II. One Dimensional Chromatopack Procedure.- III. Chromatopile Procedure.- D. Column Chromatography.- I. Columns of Cellulose Powder.- 1. Filling of the Column.- 2. Elution.- 3. Fraction CoUector.- II. Paper Roll Column Chromatography.- E. Continous Paper Chromatography.- F. Accelerated Chromatography.- I. High Temperature Paper Chromatography.- II. Centrifugal Chromatography.- References.- Determination of Size, Shape and Homogeneity of Macromolecules in Solution..- A. Average Molecular Weights.- B. Osmotic Pressure.- I. General Theoretical Considerations.- 1. Definition of Osmotic Pressure.- 2. van';t Hoff';s Law and Derivation of Osmotic Pressure Equation.- a) Ideal Charged Macromolecule-Donnan Equilibrium.- b) Non-Ideal Charged or Uncharged Macromolecule, i.e. the General Case.- 3. Extrapolation to Zero Concentration.- II. Experimental Method.- 1. Types of Osmometers.- a) Dynamic and Static Methods.- b) Membranes.- 2. Difficulties and Precautions.- C. Light Scattering.- I. Fundamental Concepts of the Theory of Light Scattering.- II. Scattering by Dilute Solutions.- III. Fluctuation Theory of Scattering.- IV. Systems of Isotropic Particles Comparable in Size to the Wave Length: Internal Interference.- 1. Dissymmetry Method.- 2. Zimm Method.- V. Polydispersity.- VI. Anisotropy and Depolarisation.- VII. Equations for Polarised Incident Light.- VIII. Scattering from Large Spherical Particles - Validity of Approximate Solution for Internal Interference.- IX. Multicomponent Systems.- X. Charged Macromolecules : Non-Random Systems.- XI. Interacting Systems.- XII. Experimental Methods.- 1. Measurement of Reduced Intensity of Scattering.- 2. Cells.- 3. Volume and Refraction Effects.- 4. Back Reflection Correction.- 5. Calibration of Light Scattering Photometers.- 6. Measurements on Coloured Solutions.- 7. Fluorescent Solutions.- 8. Measurement of Refractive Index Increment.- 9. Clarification of Solutions.- 10. Concentration of Solute.- 11. Measurement of 90° Scattering.- 12. Dissymmetry Method.- 13. Angular Intensity Measurements.- D. Diffusion.- I. Information Available from Diffusion.- II. Diffusion and the Laws of Diffusion.- 1. Types of Diffusion Measurements Carried out in Practice.- a) Steady-State Diffusion.- b) Free Diffusion.- c) Restricted Diffusion.- d) Diffusion during a Sedimentation Velocity Experiment.- 2. Feck';s first Law and Definition of Diffusion Coefficient.- 3. Thermodynamic Interpretation of Diffusion Coefficient.- 4. Fick';s second Law.- 5. Equations for Evaluating Diffusion Coefficients Using Measurements of Free Diffusion Experiments.- 6. Correction of Diffusion Coefficients to Standard Conditions.- a) Correction of D for Viscosity.- b) Correction of D for Temperature.- c) Extrapolation of D to Zero Solute Concentration.- 7. Detection of Heterogeneity by Free-Diffusion Experiments.- III. Experimental Method for Steady-State and Free-Diffusion Experiments.- 1. Steady-State Diffusion - the Diaphragm Cell.- 2. Free Diffusion.- 3. Optical Methods for Free Diffusion.- a) Schlieren Method.- b) Gouy Interference Fringe Method.- c) Rayleigh Interference Fringe Method.- d) Polarized-Light Method.- 4. Zero Time Correction.- 5. Method of Expressing Results.- 6. Example of Calculation of Reduced Height-Area Ratio.- From Schlieren Photographs of an Artificial Boundary in the Ultracentrifuge.- IV. The Use of the Diffusion Coefficient in Determining Molecular Weight.- 1. Combination of Sedimentation and Diffusion Coefficients to give Molecular Weight.- 2. Approximate Method Using Stokes'; Law.- 3. Combination of Diffusion Coefficient and Intrinsic Viscosity.- 4. Diffusion Coefficient Relationship to Molecular Shape.- V. Factors Contributing to Uncertainty in the Experimental Determination of the Diffusion Coefficients of Macro-Molecules.- 1. Interaction of Solute Flows.- 2. Charge Effects with Macromolecules.- 3. Initial Conditions - Dialysis.- 4. Purity of Solute.- E. Ultracentrifugation.- I. Information Available from Sedimentation, and General Aspects of Sedimentation Analysis.- II. The Two Facets of Sedimentation Analysis.- III. Non-Ideal Behaviour and Charge Effects.- IV. Sedimentation Velocity.- 1. The Boundary and Optical Means of Observation.- 2. The Sedimentation Coefficient and its Experimental Evaluation.- 3. Minimum Requirements from Sedimentation Analysis which must be Fulfilled if a Substance is to be Claimed as Homogeneous with Respect to Sedimentation Coefficient.- 4. More Stringent Tests which must be Satisfied by a Homogeneous Material.- 5. Expressions of the Degree of Heterogeneity of a Material.- a) Actual Distribution of Sedimentation Coefficients.- b) Method of Indicating Departure of Sedimentation Curve from that Representative of Homogeneity.- 6. Density Differences as a Test of Heterogeneity. Equilibrium Sedimentation in a Density Gradient.- V. Equation for Determining Molecular Weight from Sedimentation Velocity.- 1. The Svedberg Equation.- 2. Approximate Methods.- 3. Partial Specific Volume.- VI. Sedimentation Equilibrium and Approach-to-Equilibrium.- 1. Klainer-Kegeles Calculation of the Archibald Method when a Plateau Region is Still Present.- 2. A General Method of Calculation which can be Applied throughout the Cell whether or not a Plateau Region Exists.- 3. Method of Calculation of Molecular Weight which Gives the Weight-Average Molecular Weight of the Whole Solute once Equilibrium has been Attained.- 4. Method of Calculation which Gives the z-Average Molecular Weight of the Whole Solute once Equilibrium has been Attained.- VII. The Proportions of Components in a Sedimenting Mixture.- 1. The Johnston-Ogston Effect.- 2. Velocity Sedimentation in Systems of Reversibly-Interacting Components.- F. Viscosity.- I. Newtonian and Non-Newtonian Viscosity.- II. Functions of Viscosity.- III. Viscosity Relations for Particles of Different Shapes.- IV. Experimental Methods.- G. Particle Shape from Hydrodynamic Measurements.- I. Spheroidal Molecules.- 1. Frictional Coefficient.- 2. Intrinsic Viscosity.- 3. Combination of Hydrodynamic Methods to Give Particle Shape.- II. Randomly-Coiled Molecules.- Sectional References.- Optical Rotatory Dispersion. Its Application to Protein Conformation..- A. Mean Residue Rotation of Polypeptides and Proteins.- B. Optical Rotatory Dispersion - Drude Equation.- C. Rotatory Properties of Synthetic Polypeptides.- D. Optical Rotatory Properties of Proteins.- Existence of Structures in Proteins other than the Right-Handed ?-Helix and Random Coil.- E. Temperature Dependence of Optical Rotation.- F. Measurement of Optical Rotation.- G. Treatment of Data.- References.- Diffuse Röntgenkleinwinkelstreuung..- A. Theorie.- I. Die reine Partikelstreuung.- II. Dichtgepackte isotrope Systeme.- III. Orientierte Objekte.- B. Experimentelle Methodik.- I. Die wichtigsten Kameratypen.- 1. Kameras vom Lochblendentyp.- 2. Kameras vom Spaltblendentyp.- II. Die Monochromatisierung der Strahlung.- 1. Monochromatisierung durch Kristallreflexion.- 2. Verwendung des Rossschen Filterdifferenzverfahrens.- 3. Aussonderung der gewünschten Strahlung durch einen Impulshöhendiskriminator in Verbindung mit einem Proportionalzählrohr.- III. Die Registrierung.- 1. Photographische Messung.- 2. Impulszählung.- C. Anwendungsbeispiele.- I. Homodisperse Proteinlösungen.- II. Homodisperse Pflanzenviren.- III. Dicke der Proteidlamellen von isolierten Chloroplasten.- IV. Bestimmung der Micelldicke in "luftgequollener" Cellulose.- V. Bestimmung der Micelldicke in "wassergequollener" Cellulose.- VI. Bestimmung der Micelldicke nativer Cellulose aus dem Rånbyschen Micellpulver und aus gequollenen Ramiefasern.- VII. Gehaltsbestimmung der Micellen aus der Anisotropie der Kleinwinkelstreuung bei Cellulosefasern.- VIII. Orientierungsbestimmung aus der Anisotropie der Kleinwinkelstreuung.- Literatur.- Méthodes Calorimétriques pour l';Analyse des Végétaux..- I. Appareillage.- II. Thermogenèse de Germinations.- III. Gradients de Thermogénèse dans les Organes en Croissance.- IV. Thermogénèse des Cultures Bactériennes et Mycéliennes; Fermentations.- V. Chaleurs de Combustion d';Organes et de Produits Végétaux.- VI. Conclusion.- Références Bibliographiques.- Surface Factors Affecting the Penetration of Compounds into Plants..- A. Effect of Molecular Structure on Permeation.- B. Effect of Surface and Interfacial Factors on Potency of Treatments.- I. Factors Affecting Deposition of Materials on Foliage.- II. Factors Affecting the Absorption of Materials by Foliage.- 1. Nature of the Formulation Applied.- 2. Nature of the Plant Surface.- C. Surface and Interfacial Tension.- I. Measurement of Surface Tension.- 1. Capillary Methods.- 2. Falling Drop Method.- 3. The Ring Method.- II. Measurement of Interfacial Tension.- 1. Capillary Method.- 2. Falling Drop Method.- 3. Ring Method.- D. Wetting and Spreading.- I. Wetting and the Contact Angle.- II. Water Repellency.- III. Spreading and the Spreading Coefficient.- IV. Penetration of Porous Surfaces.- References.- Tissue and Single Cell Cultures of Higher Plants as a Basic Experimental Method..- A. History of the Method.- B. Types of Cultures.- C. Tissue Culture Media.- I. Concentrated Stock Solution.- II. Preparation of Basic Media.- III. Supplements to the Basic Media.- IV. Purity of the Water.- V. Types of Culture Vessels.- VI. Cleaning of Glassware.- VII. Aeration of the Cultures.- VIII. Sterilization of Media.- D. Isolations of Organs, Tissues and Cells.- I. Isolation and Transfer Tools.- II. Organ and Tissue Culture.- III. Embryo Cultures.- IV. Root Tip Cultures.- V. Stem Tip Cultures.- VI. Other Miscellaneous Cultures.- VII. Callus Cultures.- VIII. Some General Precautions.- E. Transfer and Maintenance of Cultures.- I. Callus Formation.- II. Testing for Sterility of Cultures.- F. Single CeU Cultures.- G. Growth Measurements.- H. Requirements for Growth of Callus Cultures.- I. The Acidity of the Medium.- II. Temperature.- III. Light.- IV. Inorganic Nutrition.- V. Carbohydrate Nutrition.- VI. Nitrogen Nutrition.- VII. Vitamins and Growth Substances.- VIII. Nucleic Acids, Purines and Pyrimidines.- IX. Complex Extracts.- J. Some Applications of Tissue and Cell Cultures.- I. Respiration and Metabolism.- II. Polarity and Organ function.- III. Studies of Plant Diseases.- IV. Single Cell Cultures of Higher Plant Cells.- K. Resume.- References.- Immunological Methods..- A. The General Principles of Immunological Methods.- B. Purification of Antigens, Immunization of Animals and Treatment of Antisera.- I. Purification of Antigens.- II. Production of Antibodies.- 1. Choice of Animals.- 2. Immunization of Animals.- Adjuvant Method.- III. The Preparation of Antisera.- 1. Bleeding.- 2. Separation of Serum.- 3. Storage of Serum.- IV. Pretreatment of the Antisera.- 1. Isolation and Concentration of Antibodies.- 2. Absorption of Antisera.- 3. Labelled Antisera.- a) Production of Fluorescein Labelled Antiserum.- b) Production of Ferritin Labelled Antibodies.- C. Serological Methods.- I. Precipitin and Agglutinin Reactions.- 1. Considerations of the Mechanism of the Precipitin Reaction.- 2. Reactions in Free Liquids.- a) In Tubes.- b) In Droplets.- c) The Agglutinin Technique.- 3. Reactions in Gels.- a) Simple Diffusion in One Dimension.- b) Double Diffusion in One Dimension.- c) Double Diffusion in Two Dimensions.- d) Interpretation of Precipitation Patterns in Double Diffusion.- e) Immunoelectrophoresis in Gels.- 4. Localization of Antigens in Tissues.- II. The Complement Fixation Test.- III. Serological Methods Based on Electron Microscopy.- IV. Serological Methods Based on Specific Activities of Antigens.- D. Antigen-Antibody Reactions in Sensitized Animals or Their Organs.- E. Quantitative Determinations of Antigens.- I. Dilution-End-Point Test.- II. ?-Optimum Test.- III. The Determination of the Amounts of Specific Precipitate.- F. Measurements of the Amounts of Antibodies in Sera.- I. The Titre of the Serum.- II. From the Determination of the ? Optimum.- G. Methods for the Determination of Relationships between Antigens.- H. Immuno-Chemical Criteria of Purity of Antigens.- J. Applications.- I. Serology in Relation to Taxonomy of Higher Plants, Fungi and Bacteria.- II. Identification of Antigenics Substances from Plants.- 1. Proteins in General.- 2. Toxins and Allergens.- 3. Substances with Enzymatic Properties.- 4. Plant Viruses.- III. Serological Studies of Cell Products.- IV. Serological Applications in the Analysis of Biosynthetic Processes.- 1. Biosynthesis during Multiplication of Plant Viruses.- 2. Localization of Virus Synthesis within Intact Plant Cells.- 3. Antigens Associated with Fungus Infection.- 4. Biosynthesis of Enzymes.- 5. The Study of the Process of Vernalisation.- Concluding Remarks.- References.- Polarography and Tensammetry..- A. Principles of Polarography.- I. (A) D.C. Polarography.- 1. General.- 2. Types of Polarographic Processes.- 3. Applicability of D.C. Polarography.- 4. Specialized Techniques.- II. A.C. Polarography.- III. Tensammetry.- Combined A.C. Polarographic-Tensammetric Processes.- B. The Practice of Polarography.- I. Measuring Outfit.- 1. D.C. Polarography.- a) A Simple, Cheap Polarograph.- b) Useful Additions to the Simple Polarograph.- 2. A.C. Polarography.- II. The Polarographic Cell.- III. Testing of the Outfit.- IV. The Taking of Polarograms.- V. Evaluation of Polarograms.- VI. Polarographic Titrations.- VII. Chromato-Polarography.- VIII. Common Faults and their Remedies.- 1. Total Interruption in the Circuit.- 2. Irreproducibility of Results.- References.- Fallout Contamination in Plants..- A. Factors which Influence the Fallout Contamination of Plants.- I. Properties and Characteristics of Fallout.- II. Plant Factors which Affect Contamination.- B. Methods of Estimating Gross Fallout Contamination in Plant Material.- I. Counting.- II. Autoradiography of Contaminated Specimens.- C. Methods of Estimating the Individual Radionuclides in Contaminated Plant Materials.- I. Radioactive Strontium.- 1. Sample Preparation.- 2. General Method of Bryant, Morgan and Spicer (1959)..- a) Preparative Procedure.- b) Counting Procedure.- c) Addenda.- II. Iodine-131.- 1. ?-Spectrometry.- 2. Radiochemical Method.- III. Caesium-137.- References.- Sachverzeichnis (Deutsch-Englisch).- Subject Index (English-German).- Table des Matières pour la Contribution: H. Prat, Méthodes Calorimétriques pour l';Analyse des Végétaux.