IQII] SHULL REVERSIBLE SEX-MUTANTS 363 



character of these plants was purely superficial and did not affect 

 the germ cells in any recognizable manner. The only bearing 

 these plants have upon the question of sex determination, I think, 

 is in the evidence they give that genetically normal males may be 

 induced in some unknown way to exhibit female characters. When 

 the male is interpreted as a Mendelian heterozygote in respect 

 to the sex-producing gene, the occurrence of such a somatic modifica- 

 tion has the appearance of a simple case of imperfect dominance, 

 such as has been noted not infrequently in other Mendelian hetero- 

 zygotes. However, the development of male organs (non-func- 

 tional) in the supposedly homozygous female, when the latter 

 is attacked by the smut (Ustilago violacea), gives support to the 

 view held by STRASBURGER (36), that not only the heterozygous 

 sex but both sexes contain in some degree the elements of the 

 opposite sex or the capacity to react in the sexually opposite 

 manner. This fact may perhaps indicate that sex is a more 

 fundamental condition than might be inferred from the frequency 

 with which it behaves as a Mendelian unit character. MORGAN 

 (23) suggests a way in which the appearance of the organs or 

 characters of one sex in individuals of the opposite sex may be 

 explained in harmony with the Mendelian interpretation of sex 

 determination. He assumes that there may be present, underlying 

 the female sex gene, a male element with respect to which all 

 individuals of both sexes are homozygous. This he indicates by 

 introducing m into all of his sex formulae. In keeping with com- 

 mon usage among geneticists, he should have used M, since he 

 intends to denote the presence of maleness. 



While recognizing the aptness of this suggestion in removing 

 some of the difficulties in the way of a general application of the 

 Mendelian explanation of sex, I am inclined to the view that the 

 Mendelian nature of sex is of secondary rather than of primary 

 consequence. May not maleness and femaleness be thought of 

 as alternative states, which can be crudely analogized with the 

 acidity and alkalinity of chemical solutions? Just as solutions 

 may be made acid or alkaline in different ways, either by qualita- 

 tive or by quantitative additions, subtractions, or substitutions, 

 or by a combination of qualitative and quantitative changes, it 



