In 1954 Max Delbrück published "On the Replication of Desoxyribonucleic Acid (DNA)" to question the semi-conservative DNA replication mechanism proposed that James Watson and Francis Crick had proposed in 1953. In his article published in the Proceedings of the
Max Ludwig Henning Delbrück applied his knowledge of theoretical physics to biological systems such as bacterial viruses called bacteriophages, or phages, and gene replication during the twentieth century in Germany and the US. Delbrück demonstrated that bacteria undergo random genetic mutations to resist phage infections. Those findings linked bacterial genetics to the genetics of higher organisms.
Matthew Stanley Meselson conducted DNA and RNA research in the US during the twentieth and twenty-first centuries. He also influenced US policy regarding the use of chemical and biological weapons. Meselson and his colleague Franklin Stahl demonstrated that DNA replication is semi-conservative. Semi-conservative replication means that every newly replicated DNA double helix, which consists of two individual DNA