ABSTRACT
The mating of a male and a female organism produces males and females in approximately equal numbers; in this equality of number it is analogous to the cross between a heterozygote and homozygous recessive. Correns 2 first showed that the analogy is more than superficial. In Bryonia the male is the heterozygous form and produces two sorts of pollen, a male-producing and a female-producing, while the eggs are all of one kind. Similar sex-determining mechanisms have since been found in most organisms. The action of the sex-determining factors is discussed in Chap. 10.
