The main objective is to study the structure of viruses, nucleoproteins and chromosomes. Particular emphasis on the internal organization of their nucleic acids. This will be attempted by using the remarkable optical properties of both DNA and RNA in their various chemical and physical states (charge, single or double strandedness, secondary and tertiary geometry alteration in aggregates and in protein complexes, etc.). The most important methods will be: a) circular dichroism (CD) and flow oriented CD; b) circular dichroic microspectrophotometry; c) electric and flow dichroism, electric and flow birefringence; d) flourescence detected circular dichroism (FDCD); and e) scattered corrected CD by fluoroscat and FDCD methods. The above techniques will give information concerning the following properties: a) the interactions between the bases of the nucleic acids, the nucleic acids and protein complexes and the proteins components with themselves in such biological structures as viruses, chromosomes and intact nuclei; b) the electric and hydrodynamic properties of the protein coats and the average orientation of nucleic acids in viruses, nucleo-proteins and chromosomes; and, c) the superorganization of nucleic acids in viruses, nucleohistone-DNA and RNA aggregate and/or complexes, and the degree of coiling of nucleic acids in intact nuclei and intact cells. With the help of the above measurements and the recently developed theory of circular intensity differential scattering (CIDS), it is hoped that models satisfying all the measurements can be constructed, giving insight on the organization of nucleic acids in biological structures, and that through this research, new diagnostic techniques of an optical nature can be developed for detecting and identifying viruses, normal and abnormal cells in cancer cytological studies and the state of the chromosome thorugh its life cycle in the intact nuclei.