This book was written by the authors with the collaboration of thirty other investigators. The chapters are divided under seven headings: virus diseases with specific localization, virus diseases of cold blooded animals, virus diseases of insects, virus diseases of plants, viruses and tumors, diseases with virus-like agents and diseases of questionable virus etiology. Many chapters are concerned with animal diseases caused by viruses. The virus diseases with specific localizations are subdivided into three groups: (a) diseases of the respiratory tract, comprising nine chapters, one devoted to psittacosis, one to influenza, one to the common cold and the others to animal diseases, (b) diseases of the nervous system, comprising thirteen chapters treating such diseases as poliomyelitis, encephalitis and rabies, (c) diseases of other organs, treated in six chapters and including such diseases as venereal lymphogranuloma, molluscum contagiosum, and epidemic parotitis. Under the heading of diseases with virus-like agents are eight chapters