Xll CONTENTS 



V. Genetic Interaction in Other Virus Groups 299 



A. Recombination with Vaccinia and Rabbitpox Strains .... 299 



B. Interactions among Intestinal Viruses 301 



C. Genetic Interaction with Psittacosis Virus 302 



D. The Berry-Dedrick Phenomenon — Transformation of 



Shope Fibroma Virus to Myxoma Virus 302 



References 305 



XII. Problems Concerning the Tumor Viruses by Howard B. Andervont 307 



I. Introduction 307 



II. Problems Reviewed 308 



A. Visceral Lymphomatosis of Chickens 308 



B. Rous Sarcoma of Chickens 314 



C. Papillomatosis of Rabbits 327 



D. Fibroma of Rabbits 335 



E. Mammary Cancer of Mice 336 



F. Leukemia of Mice 346 



III. Conclusion 363 



References 363 



XIII. The Insect Viruses by Kenneth M. Smith 369 



I. Introduction 369 



II. Different Types of Insect Viruses and the Diseases Caused. . . 370 



A. Polyhedral Viruses 370 



B. Granulosis Viruses 378 



C. Viruses without Intracellular Inclusions 379 



III. Morphology of Insect Viruses and their Associated Membranes 380 



A. Nuclear Polyhedral Viruses 380 



B. Cytoplasmic Polyhedral Viruses 381 



C. Granulosis Viruses 382 



D. Viruses without Intracellular Inclusions 383 



E. The Ultimate Infective Unit 384 



IV. Pathological Changes in the Infected Cell and the Develop- 

 ment of the Virus Particles 384 



V. Latent Infection in Insects and its Bearing on the Cross- 

 Transmission of Viruses 386 



VI. Methods of Transmission of Insect Viruses 388 



References 390 



Author Index 393 



Subject Index 407 



