The growth of this science through that century has been exponential and ever expanding.   Transmission genetics, the observable patterns of traits in plants and animals followed directly from the work of  the pioneers named above.  The study of population genetics, i.e., the distribution of genetic material through populations, was formulated about one-third  of the way through the century.   By mid-century functional relationships between metabolic processes and  their relationships to genetic materials was well under way.  Shortly after mid-twentieth century the double-helical nature of DNA and its chemical composition were revealed. From this followed one of the (now continuing) most explosive bursts of scientific development  ever  experienced.   A new  and  rapidly  growing phase of biological work emerging in the world of DNA is  molecular biology.  The genetics of immunology as well as the molecular nature of  such  matters  as cancer are  following this trail.   St. Mary's College participates in all phases of this work.