270 EVOLUTION, GENETICS, AND EUGENICS 



The factorial make-up of the various mice in Miss Durham's 

 experiments would, then, be represented as follows: 

 BICP = black 



BiCP =blue (dilute black) 

 biCP — chocolate (absence of black) 

 biCP = silver fawn (dilute chocolate) 



The following experiments indicate the mode of heredity on the 

 factorial basis: 



i. P Black (BICP)X Silver-fawn (biCP) 

 Fx ioo per cent Black (BlCP-biCP) 



F 2 Black (BICP) Blue {BiCP) Chocolate (biCP) Silver-fawn 



(biCP) 



2. P Blue (BiCP)X Chocolate (biCP) 



F, 100 per cent Black (BiCP-blCP) 



F 2 Black (BICP) Blue (BiCP) Chocolate (biCP) Silver-fawn 



(biCP) 

 9 3 3i 



3. P Blue (BiCP)X Silver-fawn (biCP) 

 Fi 100 per cent Blue (BiCP-biCP) 

 F 2 Blue (BiCP) Silver-fawn (biCP) 



3 1 



DIFFERENT KINDS OF ALBINOS 



Any one of the color types mentioned, if lacking in the factor C, 

 will be an albino, though carrying the other factors for color. For 

 example, there may be a Black-albino (BIcP), a Blue-albino (BicP), 

 a Chocolate-albino (blcP), or a Silver-fawn-albino (bicP). 



That color factors are present in albinos may be shown by the 

 following experiment. An albino had appeared in a Black stock and 

 was crossed with a Silver-fawn, thus: 



4. P Silver-fawn (biCP)X Albino extracted from Black (BicP) 

 F x 100 per cent Black (biCP-BIcP) 



Black Blue Chocolate Albino-Black Silver-fawn 



(BICP) (BiCP) (biCP) (BicP) (biCP) 



27 9 9 9 3 



Albino-Blue Albino-Chocolate Albino-Silver-fawn 



(BicP) (bicP) (bicP) 



