riddle: control of sex ratio 



323 



The work which first showed the remarkable suitability of the 

 wild pigeons for the analysis of the sex-problem was done by 

 the late Professor Whitman who devoted many years to the 

 study of these forms. Whitman obtained indisputably a pro- 

 found modification of the sex-ratio, and identified in a general 

 way some factors associated with the modified ratios. Whether 



TABLE 2 

 Sex Ratios and "Width of Cross" as Reported by Various Authors 



AUTHOR 



CROSS 



= DIFFERENT 



<?:■} 



Buffon" \ 



[ 



Suchetet < 



Phillips 



Goat X sheep 

 Dog X wolf 

 Gold-finch X canary 



Various 6 



Various 6 



Tetrao 



Lagopus X Tetrao 



Ducks 



Guinea X chicken 

 Pheasant X chicken 

 Peafowl X chicken 

 Peafowl X peafowl 

 Pheasant X pheasant 

 Pheasant X pheasant 



Species 

 Species (?) 

 Species 



Genera 

 Species 

 Species 

 Genera 



Races 



Sub-fam. 



Sub-fam. 



Sub-fam. 



Genera 



Genera 



Species 



7: 2 



3: 1 



16: 3 



74: 13 

 72: 18 

 40: 8 

 13: 7 



46:24 



Guyer' < 



6 



12 



2 



1 



14 

 12 





 

 

 

 1 

 3 



Totals: s. fam. 20.0: 0; gen. 4.9: 1; sp. 4.3: 1; rac. 1.9: 1 



° Cited by Suchetet and by Guyer. 



b As summarized by Guyer from Suchutet's studies on museum specimens. 

 c Guyer' s figures refer not to breeding data, but' to the specimens available in 

 various museums (British, Paris, etc.). 



the modified ratios signified a real control — a reversal — of sex 

 could not at that time be definitely decided. But on this ques- 

 tion he obtained three kinds of evidence, to be mentioned later, 

 and all of these indicated true sex-reversal. 



Whitman showed that "width of cross" in doves and pigeons 

 is of first importance in determining sex ratios in hybrid pig- 



