272 ANNUAL REPORT SMITHSONIAN INSTITXJTTON, 19 42 



protein. The properties of these materials may differ widely, al- 

 though in each instance the size, shape, and chemical and other prop- 

 erties are the same regardless of the source of the virus. The proper- 

 ties of materials from strains of the same virus are similar although 

 slightly different. The amounts of the materials that may be ob- 

 tained differ tremendously and appear to depend upon the host and 

 the virus or virus strain. The materials appear to be reasonably homo- 

 geneous when carefully prepared. Many different types of experi- 

 ments have demonstrated a direct correlation between the integrity 

 of structure of a given material and its virus activity. Because of this 

 and because it has not been found possible to separate virus activity 

 from these materials, there is reason to believe that they are the 

 viruses. They appear to have the properties of molecules and in 

 addition the property of virus activity, a kind of property usually 

 assigned to organisms and one which has not heretofore been ascribed 

 to molecules. Some may wish to consider that there is a sharp line of 

 division between molecules and organisms and that viruses belong 

 wholly in one or the other of these two groups. Others may wish to 

 retain the sharp line of division but place some viruses in one group 

 and other viruses in the second group. However, to a chemist it ap- 

 pears preferable to consider that virus activity may be a property of 

 molecules, that there may be no sharp line of division between mole- 

 cules and organisms, and that the viruses may provide the transition 

 between the two. One virus has been inactivated and reactivated, and 

 some idea gained of the accompanying change in structure. Studies 

 on the elementary composition, the amino acid distribution, the amount 

 and kind of nucleic acid, the immunological reactions, the effect of dif- 

 ferent enzymes, the pH and thermal stability ranges, and the effect of 

 many different kinds of chemicals have been completed on some of the 

 viruses. Extensive studies of the physical properties have also been 

 made and the existence of long-range forces between molecules has 

 been demonstrated. There is every reason to believe that the ex- 

 tension of these studies will eventually result in the solution of the 

 more fundamental problems related to the viruses, such as the nature 

 of their origin, reproduction, and mutation. 



