194 THE BEGINNER IN POULTRY 



not as a combination, but as units, we may say striving for 

 place, the black, being dominant to white, is the victor, 

 and all the resultant progeny are black. The germ cells 

 of the progeny are part pure white, and part pure black, 

 as in the parents, but in both parents and progeny, the 

 25 per cent of pure blacks added to the impure blacks 

 give 75 per cent of blacks to 25 per cent of whites. 

 Because this percentage is sustained, it is believed that 

 all the hybrids of pure black and pure white have equal 

 numbers of pure " white " and pure " black " germ cells. 

 Whenever, upon union, each parent furnishes a " black " 

 germ, the resulting progeny is pure black ; whenever 

 each furnishes a pure "white" germ, the resulting 

 progeny is pure white. But whenever one furnishes 

 a "black" and the other a " white " germ, the oppor- 

 tunity for variants is given. And, because black is 

 dominant, and each parent has one half its germs of 

 the dominant black, black overcomes the white. We 

 may show it in this way : — 



{Black, joined to Black, gives Black. 

 White, joined to White, £;ives White. 

 Black (dominant), joined to White, gives Black. 



It has been found, on rather wide trial, that structure, 

 size, shape, color, and fertility in plants, and numerous 

 characteristics in animals come under this law. In 

 sweet peas, color is dominant to white ; tallness is 

 dominant to dwarfness. The crossing of tall and 

 dwarf sorts will, therefore, give three fourths tall in the 

 progeny. " The long. Angora hair is recessive to short 

 hair in rabbits," etc. The Cambridge University Experi- 

 ment farm began, some years ago, experiments to transfer 

 immunity to rust to the best varieties of wheat, accord- 



