540 TEE POPULAR SCIENCE MONTHLY 



FACTS CONCEENING THE DETERMINATION^ AND 

 INHERITANCE OF SEX 



By H. E. JORDAN, Ph.D. 



ADJUNCT PEOFESSOK 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 ? Wliy 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 fiie organism become 

 unalterably fixed? Wliat 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 actu- 

 :ated as much by a pure scientific motive of love of truth as by the prac- 

 tical bearing of completer knowledge respecting sex-determination on 

 the matter of the control and regulation of sex. The two main prob- 

 lems involved concern the time when sex is determined and the means 

 hy 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 Cuenot has more recently obtained the same result. What is the 

 meaning of this fact? Aristotle speculated and men are still specu- 

 lating. 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 



