The study of viruses, or virology as it is now called, had its origin in 1892 when a Russian botanist, Iwanawsky, showed that sap from a tobacco plant with an infectious disease was still highly infectious after passage through a filter capable of retaining bacterial cells. From such humble beginnings the study of these 'filter-passing agents', or viruses, has developed into a separate science which rivals, if it does not excel, in importance the whole of bacteriology. The importance of viruses lies not only in the diseases they cause in every type of living organism, but also because of their intimate relationship with the living cell, in which alone they can reproduce. Their study has influenced the whole of biology by greatly increasing our knowledge of the gene, genetics, and molecular structure; there is also the possible connexion of viruses with human cancer, in view of the occurrence of many viral cancers in other animals. The book attempts to give a comprehensive but necessarily superficial survey of the subject as a whole and should help senior undergraduates and postgraduate students who wish to gain some knowledge of virology. Further information is available from the extensive bibliography.

1. Introduction.- 1.1 Virus characteristics.- 1.2 Some virus definitions.- 2. Some representative viruses-size, morphology, ultrastructure and replication.- 2.1 Size.- 2.2 Morphology.- 2.3 Ultrastructure.- 2.4 Replication.- 3. Purification of viruses.- 3.1 Plant viruses.- 3.2 Insect viruses.- 3.3 Viruses affecting the higher animals.- 4. Classification and nomenclature.- 4.1 Introduction.- 4.2 Viruses of invertebrates.- 4.3 Viruses of bacteria.- 5. Some virus diseases in man and other animals.- 5.1 Man and the higher animals.- 5.2 Insects and other invertebrates.- 6. Some virus diseases in plants and micro-organisms.- 6.1 Plants.- 6.2 Micro-organisms.- 7. The spread of viruses from host to host.- 7.1 Methods of (virus dissemination.- 7.2 Viruses and vectors.- 8. Latency, satellite and incomplete viruses, viroids and virus-like particles.- 8.1 Latency.- 8.2 Satellite viruses and incomplete viruses.- 8.3 Viroids.- 8.4 Virus-like particles.- 9. The replication of viruses.- 9.1 The virus-host relationship.- 9.2 Adsorption and entry.- 9.3 The eclipse.- 9.4 Maturation.- 9.5 Release of progeny virus.- 9.6 Replication of bacterial viruses.- 9.7 Replication of animal viruses.- 9.8 Replication of plant viruses.- 10. Virus genetics.- 10.1 The role of genetics in virology.- 10.2 Variation among viruses.- 10.3 Genetic analysis of viral functions.- 10.4 Recombination and mapping virus genomes.- 11. Tumour viruses.- 12. Tissue and cell culture of viruses.- 12.1 Plant viruses.- 12.2 Animal viruses.- 13. Virus assay.- 13.1 Plaque assay.- 13.2 Plant virus assay.- 13.3 Counting virus particles.- 13.4 Mixed virus infections.- 14. Control of virus diseases.- 14.1 Animal viruses.- 14.2 Plant viruses.- 14.3 Viruses as agents of biological control.- References.