6o TABOO AND GENETICS 



female — or 2/3, or 1/3, etc. The proof of this 

 theory is that it solved the problems. Gold- 

 schmidt was able to work out the strengths of 

 the doses of each sex in his various individuals, 

 and thereby to predict the exact grade of 

 intersexuality which would result from a given 

 cross. 



Riddle's work on pigeons (5, 6) brings us 

 much nearer to man, and suggests the results 

 noted by both Goldschmidt and LilUe. As in 

 the Free-Martin cattle, there is an apparent 

 reversal of the sex predisposition of the fertilized 

 egg. As in the gypsy moths, different grades 

 of intersexes were observed. In the pigeons, 

 it was found that more yolk material tended 

 to produce a larger proportion of females. 

 The most minute quantitative measurements 

 were made of this factor, to eliminate any 

 possibility of error. 



The chromosome mechanisms practically force 

 us to suppose that about half the eggs are 

 originally predisposed to maleness, half to 

 femaleness. A pigeon's clutch normally con- 

 sists of two eggs, one with a large yolk and one 

 with a small yolk. But the half-and-half 

 numerical relation of males to females varies 

 considerably — i.e., not all the large-yolked eggs 

 produce females or all the small-yolked ones males. 



Wild pigeons begin the season by throwing 

 a predominance of males, and the first eggs of 



