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Page:Popular Science Monthly Volume 74.djvu/544

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THE POPULAR SCIENCE MONTHLY

FACTS CONCERNING THE DETERMINATION AND INHERITANCE OF SEX
By H. E. JORDAN, Ph.D.

ADJUNCT PROFESSOR OF ANATOMY, UNIVERSITY OF VIRGINIA

SINCE the time of Aristotle numerous observations have been recorded concerning the phenomenon of sex. Long prior to this period, undoubtedly, men were vexed by such questions as: Why in the same litter of animals are some male and others female? Why in the same brood of chickens do some develop into hens and others into cocks? Why in the same family are some of the children girls and others boys? What determines that one animal or plant shall be male and another female? When does the sex of thee organism become unalterably fixed? What is the nature of sex? A great deal of light has been recently thrown upon all these questions. In modern times a solution is being attempted by refined scientific means. Statistical, experimental and cytological methods of research are being employed. The fogs of mystery enshrouding the phenomenon of sex are becoming more and more attenuated and we may confidently hope soon to see them cleared away. Much has lately been discovered that strongly indicates the probable answer to the foregoing questions. Moreover, in their attempts to elucidate the enigmas of sex, men have been actuated as much by a pure scientific motive of love of truth as by the practical bearing of completer knowledge respecting sex-determination on the matter of the control and regulation of sex. The two main problems involved concern the time when sex is determined and the means by which such determination is established.

Aristotle had noted in the case of pigeons that of two eggs laid in each batch, one generally produced a male and the other a female. He further reported that the first gave rise to the male and the second to the female. Flourens has confirmed this fact for eleven sets of eggs and Cuénot has more recently obtained the same result. What is the meaning of this fact? Aristotle speculated and men are still speculating. When Drelincourt wrote regarding the matter of sex in the eighteenth century he gathered together two hundred and sixty-two theories and hypotheses concerning the nature and cause of sex and declared them all "groundless." Blumenbach subsequently contributed another and reported two hundred and sixty-three worthless theories, having added Drelincourt's to the list. Since then the number of theories not well founded on actual facts has increased to more than five