riddle: control of sex ratio 



343 



themselves been most various. The thing that seems to have 

 been effected in all cases has been the raising or lowering of the 

 general metabolism of the treated germs. In probably none of 

 the cases in which these experimentally induced abnormal sex- 

 ratios were obtained — in other animals than the pigeon — has the 

 observer been able definitely to eliminate all the possibilities of 

 the continued determination of sex by the sex-chromosome ; but 

 several observers have been able to eliminate one or more of 

 these possibilities for their material. And all of those experi- 



table 9 



Time of Fertilization and the Sex Ratio in Cattle 



Thury and 

 Cornaz. . 



Diising" 



Dusing° 



time cf: 9 



Early 0:7 

 Late 22:0 



Early 8: 10 

 Late 4: 1 



Early 3: 10 

 Late 1 : 1 



Russell . 



Pearl and 

 Parshley. 



Early 31 : 51 

 Late 42: 34 



Early 123 

 Middle 67 

 Late 65 



125 

 58 

 42 



° Work cited by Dusing. 



6 Omitting the data submitted by Cornaz in the first announcement of the 

 theory. 



ments which strongly suggest a real sex reversal or control can 

 now be shown to be in alignment with one or more of the basic 

 facts of sex control now known in the doves and pigeons. When 

 the conditions of these experiments have been such as to lead 

 us to expect an increase of the metabolism, males have been pro- 

 duced in excess, and when the conditions imposed have been 

 obviously capable of depressing the metabolism of the treated 

 germs, these have yielded an excess of females. These facts, 

 therefore, afford much reason for the opinion that sex has been 

 controlled or reversed in a number of very different animals. 



