34 R. MARKHAM 



G. The A-Protein 80 



H. The X-Protein 81 



I. Effect of Heat on the ^"irus 82 



J. Reconstitution and the Infectivity of Virus Nucleic Acid 83 



1. Infective Nucleic Acid 83 



K. The Action of Various Agents uj on the Infectivity of the Virus 85 



L. The Nucleic Acid of the Tobacco Mosaic Virus 86 



M. The Quantity of Nucleic Acid in the Virus 88 



N. The Effect of the Host on the Virus 89 



0. Strains of the Tobacco Mosaic Virus 91 



1. Cucumber Virus 3 (and 4) 92 



2. Other Strains 93 



VII. The Tomato Bushy Stunt Virus 93 



A. Purification 93 



B. Chemical Properties 94 



C. Physical Properties 95 



VIII. The Tobacco Ringspot Virus 96 



A. Physical Properties 97 



B. Chemical Properties 98 



IX. The Turnip Yellow Mosaic Virus 98 



A. Purification 98 



B. Further Purification 99 



C. Properties of the Preparation 99 



D. The Two Components 101 



1. Points of Similarity 102 



2. Points of Difference 102 



3. The Interpretation of the Above 102 



4. The Sjrmmetry of the Top Component 104 



E. Amino Acid Composition 105 



F. The Nucleic Acid 106 



X. The Wild Cucimiber Mosaic Virus 107 



A. Purification 107 



B. The Two Components 107 



XI. The Tobacco Necrosis Viruses 108 



A. Purification 109 



XII. The Alfalfa Mosaic Virus 110 



XIII. Broad Bean Mottle Virus Ill 



A. Properties Ill 



XIV. The Southern Bean Mosaic Virus 112 



A. Purification 112 



B. Crystallization 112 



C. Physical Properties 113 



D. Chemical Composition 113 



XV. Potato Virus X (Potato Latent Mosaic Virus) 113 



A. Piu-ification 114 



XVI. The Use of Nucleic Acid Analogs in the Control of Plant Viruses 115 



A. Azaguanine 117 



References 119 



