22 THE FAMILY AND THE NATION 



one parent are all of the same kind, while those of the 

 other are of two species. There is some evidence to 

 indicate that the germ cells of the female are of two 

 kinds, while those of the male are all similar. If so, a 

 female carries both male and female characters, while 

 a male is exclusively male. The sex of any one 

 offspring is determined solely by the chance whether one 

 of the germ cells of the male meets a male or female 

 germ cell of the female. 



So far, we have dealt only with a single pair of 

 contrasted characters whiteness and blackness, tallness 

 and shortness. When the simultaneous inheritance of 

 two or more pairs of characters is examined, the 

 phenomena naturally become more complicated. 



Sometimes the two pairs of characters are transmitted 

 quite independently of each other. Grains of maize 

 may be either yellow or white, either smooth or 

 wrinkled. If a smooth yellow type of maize be crossed 

 with a wrinkled white variety, all the resulting grains 

 are smooth and yellow. Thus smoothness and yellow- 

 ness are dominant characters, and wrinkledness and 

 whiteness recessive. To investigate the nature of these 

 apparently similar plants, they are crossed with the 

 wrinkled white variety. As these characters are reces- 

 sive, they only appear when the germ cells of the 

 dominant hybrid possess them also. Hence the result 

 of this experiment gives the nature of all the germ 

 cells of the hybrid. It was found that some eleven 

 thousand grains were divided almost exactly equally 

 between grains which were smooth and yellow, grains 

 smooth and white, grains wrinkled and yellow, and 



