Hermann Paul August Otto Henking (16 June 1858 – 28 April 1942) was a German cytologist who discovered the

X chromosome The X chromosome is one of the two sex chromosomes in many organisms, including mammals, and is found in both males and females. It is a part of the XY sex-determination system and XO sex-determination system. The X chromosome was named for its u ...

in 1890 or 1891. The work was the result of a study in

Leipzig Leipzig (, ; ; Upper Saxon: ; ) is the most populous city in the States of Germany, German state of Saxony. The city has a population of 628,718 inhabitants as of 2023. It is the List of cities in Germany by population, eighth-largest city in Ge ...

of the testicles of the firebug (''Pyrrhocoris apterus''), during which Henking noticed that one chromosome did not take part in

meiosis Meiosis () is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, the sperm or egg cells. It involves two rounds of division that ultimately result in four cells, each with only one c ...

. He named this the ''X element'' because its strange behaviour made him unsure whether it was genuinely a chromosome. It was later named the X chromosome after American cytologist Clarence Erwin McClung established that it was not only a genuine chromosome but a sex-determining one, though McClung incorrectly guessed that it was the male-determining sex chromosome.David Bainbridge, ''The X in Sex: How the X Chromosome Controls Our Lives'', pages 3–5, Harvard University Press, 2003 .

References

1858 births 1942 deaths 20th-century German biologists 19th-century German biologists {{Germany-biologist-stub