INHERITANCE OF SEX 

 c? 



229 



>6> 



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

 accompanied by a smaller x or Y chromosome, as in Lygaeus bicrucis. 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 Y but no 

 X and produce males. (From Morgan.) 



