THE DETERMINATION OF SEX 



217 



Doncaster and Raynor, in 1908, published the results 

 of various crosses between these two varieties which 

 demonstrate clearly that sex is a Mendelian character 

 and that, in this instance, maleness is homozygous 

 and femaleness heterozygous with the determiner 



KEY TO SYMBOLS 



PHENOTYPE 



GROSS.cf 



GROSS.d 1 



LACT-c? 



Constitution with 

 respect to the 

 ;ROSSULARIATA 



Dupl ex 



Simplex 



Multiplex 



Simplex 



Nulliplex 



GENOTYPE 



(Joi Im 



Ooi 



GAMETES 



FIG. 67. Key to the symbols employed in Figures 68-71. The outline 

 symbols represent samples of the autosomes or somatic chromosomes. 

 The black symbols stand for the "extra" or sex chromosomes. O 

 above a black symbol indicates the grossulariata factor linked with a 

 sex chromosome. The variety lacticolor occurs whenever the grossu- 

 lariata factor ia absent. 



for maleness linked with the factor producing the 

 variety grossulariata. A study of Figures 67-71 

 will make this case clear. Outline symbols represent 

 ordinary chromosomes or autosomes, several of which 

 are omitted for sake of clearness. The black sym- 

 bols represent sex chromosomes. The letter G placed 



