SEX INHERITANCE 131 



characters peculiar to them. Within the class, 

 there is great fluctuation — on the one hand to in- 

 dividuals entirely male in appearance, and on the 

 other to individuals nearly all of whose character- 

 istics are female. An intersex of a high ''female- 

 type" is an individual in which most of the parts 

 are purely female, a few parts are male, and others 

 are mixtures. The mid-grade intersexes usually 

 have rudimentary ovaries; but not infrequently 

 one gonad is a rudimentary testis, or a rudimentary 

 ovary with a folhcle budding into a testis. The 

 testes of high grade male-type intersexes are like 

 those of normal males in size and appearance. All 

 intersexes are sterile. The stock is maintained by 

 breeding from sisters of the intersexes. Only a 

 small proportion of these gives intersexes. Genetic 

 tests and cytological examination show that the 

 intersex-producing females are triploid (3n), pos- 

 sessing three representatives of each of the four 

 chromosomes. Likewise the intersexes are shown 

 to be triploid for the airtosomes, but only dii)loid 

 for the X-chromosomes. Individuals with two X- 

 chromosomes are not females if a third set of auto- 

 somes is present; they are altered to a greater or 

 less extent into males. Accordingly, the autosomes 

 are shown to be as concerned in the production of 

 sex as are the so-called sex-chromosomes. The X- 

 chromosomes are seen to be chromosomes that are 

 female determining in tendency, while the auto- 

 somes are male determining. 



If the chromosomes determine sex Ijy means of 



