MENDELISM AND SEX 157 



better represented by constituting the alternative 

 characters as presence of greyness versus absence 

 of greyness which gives blackness.* The presence 

 of the character is thus dominant to its absence. 

 So that presence of greyness is not said to be dominant 

 to the presence of blackness, but to the absence of 

 greyness. In the sense that the terms dominant and 

 recessive are applied to the manifestation or non- 

 manifestation in the zygote of the two unit-characters 

 of an alternative pair, the terms are still used in the 

 way in which Mendel employed them. But, as we 

 have just seen, the conception of the nature of 

 alternative characters has been modified. Dwarf- 

 ness, for instance, is not now regarded as another 

 quality to tallness, but simply as that condition 

 which results from absence of tallness. Add the 

 factor which determines tallness to dwarfness, and 

 tallness is manifested. And similarly in respect to 

 sex. We may conceive that femaleness is due to a 

 germinal factor which determines the manifestation 

 of that sex. It is something which is added to 

 maleness, and in its absence maleness is manife.sted. 

 The two alternative unit -characters of sex are there- 

 fore presence and absence of femaleness. 



This conception of sex seems to be applicable to 

 all cases which have yet been investigated, and it 

 enables us to give a consistent interpretation of the 

 facts in the two types of sex-inheritance which we 

 have studied. Thus, if we let F represent femaleness 

 and / its absence, then in man, since the female 



* Grey being epistatic to black wliich is hypostatic. 



