CHAPTER IX 



REPULSION AND COUPLING OF FACTORS 



Although different factors may act together to 

 produce specific results in the zygote through their 

 interaction, yet in all the cases we have hitherto 

 considered the heredity of each of the different factors 

 is entirely independent. The interaction of the 

 factors affects the characters of the zygote, but makes 

 no difference to the distribution of the separate 

 factors, which is always in strict accordance with 

 the ordinary Mendelian scheme. Each factor in 

 this respect behaves as though the other were not 

 present. 



A few cases have been worked out in which the 

 distribution of the different factors to the gametes 

 is affected by their simultaneous presence in the 

 zygote. And the influence which they are able to 

 exert upon one another in such cases is of two kinds. 

 They may repel one another, refusing, as it were, to 

 enter into the same gamete, or they may attract one 

 another, and, becoming linked together, pass into 

 the same gamete, as it were, by preference. For the 

 moment we may consider these two sets of pheno- 

 mena apart. 



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