INHERITANCE OF SEX 



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FIG. 100. Diagram illustrating the history of the sex chromosome when 

 accompanied by a smaller .v or Y chromosome, as in Lygaeus bicrncis. The male 

 cells have twelve ordinary chromosomes and two sex chromosomes, one larger 

 (X) than the other (F). The resulting spermatozoa from each primordial cell 

 differ; two have X and produce females on uniting with eggs, two have F but no 

 X and produce males. (From Morgan.) 



