SEX INHERITANCE 129 



If a Japanese female is crossed to a European male, 

 the Fi female and male may be represented in the 

 following formula: 



Fi 9 (FF) Mm Fx cf (FF) M M 



100 60 100 80, 60 



Both ''normal" female and male offspring are 

 expected in equal numbers. The reciprocal cross 

 gives a different result viz.: 



Fi 9 (FF) :\Im F. cf (FF) M M 



80 80 80 80, 60 



The Fi female is FF - M = 0; and is therefore 

 represented as intersexual. It will be observed that 

 the so-called ''female factors" in these formulae 

 are supposed to be inherited entirely through the 

 mother. 



By assigning different values to FF and M in 

 the different races it is possible to express the results 

 in such a way that the sexes obtained by various 

 crosses have different minimal values — those less 

 or more than any assigned value for a given sex 

 are interpreted as intersexes. In the example 

 cited, an exact balance (= 0) between the con- 

 flicting factors produces an individual that is neither 

 male nor female, but made uj) of a mosaic of parts 

 each of which is rouglily comparable to the same 

 part in a male or a female. 



A series of crosses between species of Biston 

 have been made by J. W. Harrison. The sex ratios 

 are altered and in some cases intersexual females 



