In 1869, Swiss physician and chemist Friedrich Miescher isolated DNA from the nuclei of sperm, sperm cells, and red blood cells of birds. He named it Nuclein. In 1874 he isolated nucleic from salmon sperm and named it protamine. In 1880 scientist Fisher discovered purine and pyrimidine. In 1889, Altmann named nucleic acid as nucleic acid. Albrecht Kossel discovered adenine, guanine, cytosine and thymine in 1910. In 1910 scientist Leven discovered deoxyribose sugar. In 1914, German chemist Robert Feulgen invented the Feulgen staining method for DNA. In 1928, British scientist Frederick Griffith realized that DNA contains all genetic information. In 1950 Erwin Chargaff mentioned Chargaff’s rule of DNA. At the same time, Maurice Wilkins and Rosalind Franklin presented the physical structure of the DNA molecule using X-ray crystallography. In 1952, Hershey and Chase proved that DNA is the genetic material of organisms. In 1953, J. D. Watson and F. H. Crick proposed the generally accepted model of DNA.