CHAPTER III
THE MYSTERY OF SEX AND SEX-TRANSMISSION
"The idea that the female is naturally and really the superior sex seems incredible, and only the most liberal and emancipated minds, possessed of a large store of biological information, are capable of realising it."—Professor Lester Ward.
I
Those happy persons who do not perplex themselves concerning the intrinsic causes behind all physical phenomena see it as only "natural" that two parents of opposite sex should produce offspring of both sexes.
And yet it is not only a great mystery, but, on the face of it, it is an anomaly that a child who may possess an admixture of all the physical and mental characteristics of its two parents, bears, nevertheless, the sex and the sex-characteristics of one only. Sex, male or female, breeds true in nearly every case; the rare exceptions merely emphasising the rule. The mystery deepens when we realise that every individual is a product of countless such admixtures of the qualities, throughout countless generations, of countless forefathers and foremothers. And although such a man or woman may hark back to any one, or more, of the traits of his or her innumerable forbears, he or she, nevertheless, "breeds true" in the factors of sex and sex-characteristics.
Long and closely biologists have pondered these many and involved problems. How is it, they inquire, that an embryo bred of two parents of opposite sex develops the sex of one only of these? How is it that the mother, who belongs to one sex only, produces—and produces in about equal number—offspring of both? The phenomenon is expressed, biologically, in the term, "sex-limited factor"—an incalculable something in the embryo which limits its sex to the sex of one only of its parents. But the "something," and the method of this sex-limitation have remained enigmas.
Sex is regarded by the new Mendelian school of biologists as that which is known as a "Mendelian factor." And to follow the argument to its conclusions, a few simple words about the Mendelian theory of Heredity are essential to those unacquainted therewith.
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About forty years ago, a German monk, Mendel by name, was struck by the facts that in his bed of edible peas certain plants grew tall, while others remained dwarf; that the blossoms of certain plants were white always, while those of others were always coloured. He made a number of experiments in crossing the plants, with a view to discovering the law of inheritance by way of its operation in hybrid varieties. Briefly, the results of his experiments—which have since been repeated and confirmed by many later observers—were as follows: