VIROSBS 54 



cause virus Infection is the most reasonable starting point for speculation con- 

 cerning the nature of virus reproduction. 



In the first chapter the theory that viruses are molecules was introduced, 

 and in it and the two subsequent chapters, data were presented which were gath- 

 ered as an outgrowth of this theory. In this chapter viruses have been discussed 

 from the point of view that they are organisms. The final chapter will be pre- 

 dicated upon the same point of view. Many readers will readily understand my 

 lack of reluctance to shift points of view, but a few might deplore my apparent 

 lack of consistency. The primary function of science is the discovery, corre- 

 lation and understanding of the properties of the universe. Theories are useful 

 tools which can be employed in that task. A good theory is one which suggests 

 new means of unlocking nature's secrets. In the field of virology, we are very 

 fortunate in having two excellent theories, one that viruses are molecules and 

 the other that they are organisms. Each suggests its own types of experiments 

 to advance knowledge. Some of the fruits of the molecular theory have been re- 

 viewed in some detail. One of the most promising possibilities suggested by the 

 organismal theory is the ultimate ability to cultivate or grow viruses on syn- 

 thetic media. This would be a tremendously important achievement. Thus it is 

 fortunate that there are two apparently conflicting hypothesis and that some 

 people adhere to one and others to the other. It doesn't make any real differ- 

 ence which is right, or even if neither is right. 



