594 CALVIN B, BRIDGES 



vermilion and eosin males respectively. Thus for four sex chro- 

 mosomal factors the same conclusions hold. 



Since it has been shown that the non-disjunctionally produced 

 female hands her peculiarity on directly to her Fi non-disjunc- 

 tional daughters, we can test the non-dis junctional sons in that 

 respect. The offspring of the white miniature exceptional male 

 give us no information on the question, because the classes 

 of offspring which would show the effect can not be separated 

 from the large normal class already present. The vermilion pink 

 male, however, I mated to wild females. The first generation 

 consisted of red females 223 and red males 159 and 7io non-dis- 

 junctionals. F2 was like that from a normal stock vermilion 

 pink male, namely: 



The fact that the non-disjunctional female gives non-disjunc- 

 tionals in Fi is the result one would expect if the cause of this 

 peculiar oogenesis were itself a sex chromosomal gene. If such a 

 gene were present in each of the sex chromosomes of the origi- 

 nal female all her exceptional daughters would of course have 

 the same condition and thus the line would be perpetuated par- 

 thenogenetically, so to speak, indefinitely. But with regard to 

 the exceptional male it should be otherwise, for he gets no sex 

 chromosome from his mother and consequently can neither have 

 jior transmit the non-disjunction gene. 



Before passing to the next instances, I can present some evi- 

 dence on the composition of the normal pink females and white 

 males produced in the cross of the white pink non-disjunctional 

 female to the vermilion pink male (out-cross). A few of the 

 normal pink females and white males produced: 



pink9(4) white9(4) white cf (4) verm, pink cf (3) pinkd^ (1) 



74 77 66 62 15 



The simple ratio is altered somewhat by association of white and 

 vermilion, but, is otherwise a wholly normal result. 



