VIRUSES 



certain enzymic activities quite tenaciously, whereas tobacco mosaic 

 and bushy stunt viruses appear lo possess no enzymic activities other 

 than that of virus activity. It is also of interest that, in marked con- 

 trast to bacteria and other ceils, tobacco mosaic and influenza viruses 

 contain negligible amounts of the B vitamins. Electron micrographs 

 of vaccine virus, as well as of certain bacteriophages, have revealed 

 the presence within individual particles of an internal structure con- 

 sisting of a pattern of granules. 



As a whole, the data now available on viruses indicate that, as 

 one goes from the small to the large viruses, there is, with increase in 

 mass, an increase in complexity of composition, structure, and function. 

 The viruses appear to provide, in truth, a bridge between proteins 

 and organisms. Indeed, if one wishes to regard the transformation 

 agent of the pneumococcus as a virus, the bridge could be extended to 

 nucleic acid. If one were starting out anew to construct a link between 

 the molecules of the chemist and the organisms of the pathologist or 

 bacteriologist, it is difficult to visualize how it would be possible to 

 improve upon what Nature has already provided. The structural 

 complexity encountered in tomato bushy stunt virus nucleoprotein is 

 but little more complex than that of hemoglobin and no more complex 

 than that of the hemocyanins. Physically and chemically these behave 

 as molecules; and if it were not for the virus activity of the bushy stunt 

 nucleoprotein it would not be given a second thought. Between bushy 

 stunt virus and vaccine virus. Nature has provided a continuous series 

 of structures of gradually increasing mass and complexity, all linked by 

 a common biological property, virus activity. Vaccine virus is as 

 large as some organisms that can be grown on artificial media; and if 

 vaccine virus could be grown on artificial media it would be accepted 

 generally as an organism. Even larger structures exist which cannot 

 be grown on artificial media and which are just as fastidious as vaccine 

 virus with respect to growth requirements; yet these are accepted as 

 organisms. Nature has provided us with an accomplished fact, and it 

 is time for all to brush away the barriers of the mind and to recognize 

 the possibilities that are provided by the viruses. Although viruses are 

 disease-producing agents and have caused untold suffering, the com- 

 plete acceptance of Nature's dubious gift may not be without recom- 

 pense. For its acceptance and exploitation may provide ihc key to 

 broad and wonderful vistas. 



17 



