1 86 



Outline of Genetics 



the two normal types of sperms from a red male will result in four 

 possible types of zygotes: 



A {vX) {vX) egg with a {VX) sperm gives a {vX) iyX) {VX) 

 zygote, which might be expected to produce a red female, but 

 actually dies (according to Bridges' earlier statements). 



A {vX) {vX) egg with a Y sperm gives a {vX) {vX) Y zygote, 

 which produces a vermilion female. 



Fig. 30. — Showing the four types of zygotes which result from mat- 

 ings between non-disjunctional eggs of vermilion female and normal 

 sperms of red male. Note particularly the second and third z\-gotes, 

 which produce the "exceptional" individuals, vermilion female and red 

 male. 



An O egg with a (VX) sperm gives a (VX) zygote, which 

 produces a red male. 



An O egg with a Y sperm gives a Y zygote, which dies. 



Inasmuch as vermilion female crossed with red male normally 

 gives only red daughters and only vermilion sons, the vermilion 

 daughters and red sons which result from the non-disjunctional 

 eggs appear as startling exceptions to the normal rule. The 



