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.
From its roots in the work of Gregor Mendel analyzing the inheritance patterns in pea plants, and T. H. Morgan and his collaborators, who extended Mendel's hypotheses to wing and eye features in fruit flies, genetics developed as an intellectual and laboratory discipline at the beginning of the twentieth century.