Calvin Blackman BridgesDied 27 Dec 1938 at age 49 (born 11 Jan 1889).American geneticist who advanced understanding of the role of chromosomes in heredity using the fruit fly, Drosophila melanogaster. He began, in 1910, as a laboratory assistant for Thomas Hunt Morgan tracking how observable changes in its chromosomes led to inherited variations. Bridges used natural "mistakes" in sex chromosome segregation to show that an improper number of chromosomes produced abnormal fruit flies. Such "mistakes," called nondisjunction because chromosomes are not properly disjoined, result in gametes with either an extra copy of a sex chromosome or none at all. He created a nomenclature system for naming fly mutants. He correlated Drosophila genes with banding patterns in salivary chromosomes.«[Image right: fruit fly (source) ] |
