THE PROBLEMS OF VIROLOGY 13 



it infects but no "breakthrough" has yet appeared to initiate the phase of 

 infinitely elaborate investigation. 



Any experimental biologist could provide a similar picture for his own 

 particular field of study. The potentialities are infinite. To some this may 

 provide a happy picture of an endless stream of experimental biologists 

 finding intense and subtle enjoyment through centuries to come. To those 

 concerned with the problem of how to present the current state of knowledge 

 in such a field as the interaction of virus and host cell, it presents over- 

 whelming difficulties. 



Perhaps the most modest and practical approach to adopt is to regard the 

 function of the generalization, the textbook and the treatise, as simply to 

 provide an adequate index and guide to available knowledge. Knowledge of 

 any aspect of the universe may be needed and it is the function of the expert 

 in both academic and practical worlds to be able to find and supply what is 

 known of his subject as rapidly and completely as possible. It may be that 

 in biology truth is a particidarly elusive concept but there may be many 

 approximations to truth — incomplete or speculative generalizations — which 

 can assist the intelligent search for and utilization of available know- 

 ledge. 



In virology, as in other biological domains, the current effort can perhaps 

 be stated as to seek out a smaU series of model systems for which there can 

 be sketched out a set of working hypotheses which are not inconsistent with 

 the facts available, and which provide a means of marshalling and indexing 

 factual data as well as suggesting lines for further study. Any approach to 

 other systems — to the prevention of a hitherto unknown virus disease, for 

 instance — will then be guided by what is the accepted picture for the model 

 system which appears most relevant to the new situation. 



This point of view carries the implication that it is desirable and necessary 

 at every stage in the development of a biological science that reviews and 

 textbooks should state, with all necessary qualifications, those generaliza- 

 tions which appear at the current stage to provide help to understanding. 

 The form in which generalizations are to be stated is quite immaterial pro- 

 vided it is helpful in the sense we have used. 



For obvious reasons, generalizations within a given biological field must 

 not be incompatible with the concepts which are accepted as valid for some 

 broader inclusive field. Throughout the history of science, special value has 

 been placed on the discovery of concepts of wide application or on the recog- 

 nition of how in a new field old concepts with or without modification can 

 still be shown to be valid. It is a special feature of present-day biology that 

 almost all the special fields find a point of common convergence in the 

 problems of the synthesis of specific nucleic acid and protein macromole- 

 cules. The study of virus multiplication in the host cell may throw light on 



