CHAPTER X 



HEEEDITY AND SEX 



THE value of a domesticated animal often 

 depends in considerable measure on its 

 sex. Therefore, if a means could be 

 devised for controlling the sex of offspring, it 

 would be of great economic value to the breeder. 

 Endless attempts have been made to do this, 

 and occasionally a claim of success has been 

 made, but none of these claims has withstood 

 the test of critical analysis or experiment. The 

 hypotheses advanced to explain how sex may 

 be controlled have been of the most varied 

 character. In some the determination of sex 

 has been supposed to inhere in the nature of 

 the parents, in others it is referred to condi- 

 tions of the gametes themselves. 



Relative age or vigor of the parents have 

 been supposed to influence sex in various ways. 

 The same idea has been advanced regarding 



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