132 SEX INEHRITANCE 



genes carried in them, we may say: — both sexes 

 are due to the simultaneous action of two sets of 

 genes, one set, located predominantly in the X- 

 chromosome, tending to produce the characters 

 called female, the other set, located predominantly 

 in the autosomes, tending to produce the characters 

 called male. These two sets of genes are not equally 

 effective, for the female-tendency genes outweigh 

 the male-tendency genes, and the diploid (or 

 triploid) form is a female. When the relative 

 number of the female-tendency genes is lowered by 

 the absence of one X, the male tendency genes 

 outweigh the female, and the result is the normal 

 haplo-X male. When the two sets of genes are 

 acting in a ratio between these two extremes, as is 

 the case in the ratios of 2X : 3 sets of autosomes, the 

 result is a sex intermediate — the intersex. 



Individuals that have 3X: 2 sets of autosomes 

 (superfemales) and IX : 3 sets of autosomes (super- 

 males) are likewise produced by triploid (3n) 

 females. They have been identified by genetic and 

 cytological tests. They form distinct types that are 

 easily distinguishable from normal females or males, 

 and they are sterile. 



Sex and Sex-determining Gametes 



The word sex is usually applied to many-celled 

 individuals, the male sex producing sperm and the 

 female sex producing eggs. In most races the male 

 and the female sex have the diploid (double) number 



