NON-DISJUNCTION OF SEX CHROMOSOMES 595 



Two other white pink females (of the nine) I mated separately 

 to wild males. They produced: 



redcf 



8 



11 



12 343 278 19 



These two instances illustrate once more the fact that the sex 

 chromosomal character of the non-dis junctional female depends 

 solely upon the sex chromosomal character of her mother and in 

 nowise upon that of her father. But with the non-disjunctionally 

 produced male the result is exactly reversed, for each time the 

 character of the non-dis junctional male depends not upon the 

 characteristics of the mother (other than non-disjunction itself) 

 but is a duplicate of that of his father, in this case completely 

 normal. 



If the third chromosome is not involved in this non-disjunction 

 then we should expect that as far as the distribution of pink is 

 concerned, the results would be exactly that of a normal cross, 

 that is, both the non-disjunctional females and males should be 

 heterozygous for pink, because their mother was homozygous 

 for pink and their father was not-pink. To test this point further 

 I crossed three non-disjunctionally produced females (of the 

 twelve) to non-disjunctionally produced males (of the nineteen). 

 The next generation was: 



8 153 79 256 



One can see here in the same cross both non-disjunction and 

 normal segregation, but with respect to different chromosomes. 

 The non-disjunction results are, the sons all white to correspond 

 to the composition of their mother, and the occurrence of the 

 white non-disjunctional females. The production of pink females 

 shows that both parents were heterozygous for pink, since if 



