XVI PREFACE 



to write authoritatively about all of the important aspects of virology, it 

 has been necessary to seek the assistance of experts in different areas of 

 virology. The editors have been quite fortunate in securing contributions from 

 34 of the leading virologists in 8 different countries. Almost two-thirds of the 

 contributors are from American laboratories and this mirrors with reasonable 

 accuracy the relative activity in virology during the past several years. 

 However, there is presently a great upsurge of research activity in virology 

 in several countries and significant new information is now almost world- 

 wide with respect to source. 



The plan of "The Viruses" has deliberately followed that of the works on 

 "The Proteins," "The Nucleic Acids," and "The Enzymes" published also 

 by Academic Press. In this treatise on "The Viruses" we are concerned essen- 

 tially with the chemical and physical characteristics of viruses and with the 

 processes associated with their multiplication in the cell. In general we are 

 not concerned with manifestations of viral infection in multicellular organisms 

 or in populations of susceptible hosts except insofar as they provide informa- 

 tion about processes at the cellular level. It is manifestly impossible to 

 treat comprehensively of viruses without consideration of their behavior 

 at the genetic level. Particularly with the bacterial viruses there is now much 

 information on record on recombination between viruses and on interaction 

 between the genomes of virus and host cell. In this region we may well find 

 the material from which will come eventually an understanding of the 

 relationships between the genetic and chemical approaches. The discovery 

 of infectious nucleic acid preparations represents a major start in this 

 direction. 



It would not be realistic to separate the academic approach to virology 

 sharply from the clinical. In the last analysis the prevention or cure of virus 

 disease will depend on properties of virus and host cell. In the past, success 

 in contiol has depended almost exclusively on the use of procedures at the 

 immunological or epidemiological levels, but if these are to be refined and 

 fully understood much use will have to be made of the information provided 

 by the essentially theoretical studies which the present work has been 

 designed to systematize and display. Consider, for example, the new immuno- 

 logical problems that one may encounter if, as may emerge, infectious 

 nucleic acid moves directly from cell to cell. This treatise provides the 

 information and the interpretation of this information that will be necessary 

 for a rational experimental approach to such new problems. 



One of the main difficulties the editors have encountered has been one 

 inherent in all attempts at biological generalization, namely, the diversity 

 of the material that is available for study and the widely varying intensity 

 and success with which different sections of that material have been studied. 

 It will be found, for instance, that a large proportion of each of the three 



