Born-5 September 1866 AD and died-4 December 1945 AD. He was a citizen of the United States. He is an American geneticist, evolutionary scientist, and embryologist. He proved that chromosomes are inside the cell nucleus and genes are located in chromosomes. Genes are arranged in sequence and are transmitted as hereditary traits. Describe the mechanism of transmission of hereditary characteristics. Chromosomal theory explains the linear arrangement of genes on chromosomes, crossing over and mutation. His books are – The Mechanism of Mendelism Heredity, The Theory of Gene, Heredity and Sex etc. Awarded Nobel (1933), Member of the National Academy of Sciences (1909).