198 DISTRIBUTION OF THE CHROMOSOMES 
The same series of eggs fertilized by the male- 
producing sperm, which carries a Y chromosome, 
would give: 
(5) 
vy yYY 30Y. YY 
O white O white Q white dies 
If we consider these eight kinds of progeny we 
see that the exceptional white females (7) would be 
expected to repeat the process and be non-disjunc- 
tional. This is what actually occurs, for all white 
females that are the product of such a cross do, in 
fact, give non-disjunction in the next generation. 
The red males (4) are an exceptional class but 
should not give exceptional results when bred to any 
normal female, nor should they transmit non-dis- 
junction. This has been shown to be true. 
The red females are not alike in composition, half 
of them (1) should behave like normal females 
heterozygous for white and the other half (2) should 
give exceptions. There are in fact found to be 
these two kinds of red females in equal numbers. 
The white males (5) and (6) are not alike; one 
kind (5) is normal and the other (6) has two Y 
chromosomes. The latter should be expected to 
produce some XY sperm. These sperm would give 
daughters which would not be exceptions, but such 
females, with a formula XXY, should produce 
exceptions. In fact from half of the white males (5 
and 6), daughters are produced that give non-dis- 
junction. 
