ABSTRACT
It was realized in the very early days of Mendelism that there is some connection between sex determination and Mendelian heredity. Even before the rediscovery of Mendel's 2 work, Bateson in 1894 pointed out that sex is an example of discontinuous variation, and included it in the body of facts which, presented as Materials for the Study of Variation, nearly brought him independently to the idea of discontinuous hereditary units. Correns 3 was the first to give an actual demonstration that the connection was a real one. He showed that in Bryonia the male is heterozygous for sex factors, and produces two classes of pollen, while the female corresponds to the homozygous recessive. This was soon followed by the discovery of unequal sex chromosomes by McClung.
