MATERIALS OF HEREDITY 



17 



Oerm cells 



Sale 



Oerm cells 



l^emale 



Figure 5. Continuation of the diagram of figure 4. Formation of 

 male and female individuals (fertilized eggs) by the union of germ 

 cells from the male and female parents. Chromosomes from males 

 represented in outline, from females solid. A, formation of a male 

 individual by union of a male germ cell bearing no X, with a female 

 germ cell that bears an X. B, formation of a female individual, by 

 union of a male germ cell bearing X with a female germ cell likewise 

 bearing X. The X-chromosome of the male parent thus goes only to 

 his daughters, not to his sons. 



chromosomes develop into females, the eggs that lack one 

 of the chromosomes develop into males. And it has been 

 fully proved, by a great variety of observations and ex- 

 periments, that the difference of sex Is certainly due to the 

 original chromosome difference. The same egg that would 

 produce a female, actually produces a male If one of the 



