TABOO AND GENETICS 65 



the two sexes. Some of the main facts are 

 known, however, and the general effects of the 

 two diverse chemical systems upon the life 

 cycles of the sexes are quite obvious. What we 

 call the " quantitative theory of sex " has, 

 besides a place in exact science, an interesting 

 relation to the history of biological thought, 

 especially as applied to society. It is thus in 

 order to state as clearly as possible what it 

 now is ; then, so that no one may confuse it 

 with what it is not, to run over some of the old 

 ideas which resemble it. 



Experiments with transplanted sex glands, 

 with sex-gland extracts (testicular and ovarian) 

 and the observation of infusions of a male-type 

 blood-stream into a female body, as occurs in 

 nature in some cattle and in the so-called human 

 " hermaphrodites," indicate a gross chemical 

 difference between the respective determiners 

 for femaleness and for maleness. So the chemi- 

 cals involved, though not yet isolated, must be 

 presumed to be qualitatively different, since 

 they produce such different results. 



But such experiments also indicate that both 

 determiners must be present in some propor- 

 tions in every individual of either sex. The 

 basis for both sexes being present, the one 

 which shall predominate or be expressed in the 

 individual must depend upon the quantitative 

 relation between the determiners which come 



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