Vlll ILLUSTRATIONS 



12. Course of inheritance of a recessive character 31 



13. Course of inheritance of white eye and red 



eye in Drosophila 33 



14. Fertilized egg of Ascaris 39 



15. Transformation of the condensed chromo- 



somes 42 



16. Hybrid egg about to divide 44 



17. Relation of body cells and germ cells 46 



18. Nature of changes in a pair of chromosomes 49 



19. The 48 chromosomes in man 57 



20. Results of failure of the two X-chromo- 



somes to separate 60 



21. Chromosomes in diploid and triploid Droso- 



phila 63 



22. Germ gland in the pig 69 



23. Experiments in exchanging germ glands 72 



24. Descent of a recessive X-chromosome, with 



outbreeding 86 



25. Descent of a recessive X-chromosome, with 



inbreeding 88 



26. Inheritance through the X-chromosomes 



with normal and with aberrant distribu- 

 tion of X 92 



