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THE AMEBIC AN NATURALIST [Vol.XLV 



characters of the female, if their development is in part 

 suppressed by substances made in the testis. 



The view here presented also allows us to explain how 

 the secondary sexual characters of the male are trans- 

 mitted through the female, as they may be so transmitted. 



The Inheritance of Sex-limited Characters 



In recent years a new class of facts has been discov- 

 ered that promises to throw a flood of light not only on 

 the sox determination problem, but also on the problem 

 of inheritance in general. I refer to the cases of sex- 

 limited inheritance. 



We mean by sex-limited inheritance that in certain 

 combinations a particular character appears in one sex 

 only. An example will make this clear. In one of my 

 cultures of the red-eyed fly, Drosophila, a white-eyed 

 male appeared. Bred to red-eyed females, all of the off- 

 spring, male and female alike, had red eyes. These 

 inbred produced red-eyed males and females, and white- 

 eyed males. In other words the white-eyed mutant 

 transmitted his character to half of his grandsons, but 

 to none of his granddaughters. 



Yet this white-eyed condition is not incompatible with 

 femaleness ; for, it can be artificially carried over to the 

 female by making a suitable cross. If, for instance, a 

 white-eyed male is crossed with a heterozygous red fe- 

 male, there will be produced red-eyed males and females 

 and white-eyed males and females. 



There are certain combinations of sex-limited char- 

 acters that give results outwardly similar to sexual 

 dimorphism. If a black langshan cock is crossed to a 

 dominique hen, all of the sons are barred and all of the 

 daughters are black. If a white-eyed Drosophila female 

 is crossed with a red male all of the sons will have white 

 eyes, and all of the daughters will have red eyes. I have 

 another strain of these flies with small wings and still 

 another strain with truncated wings. If a female of the 

 former is crossed with a male of the latter strain all of 



