Wilson — Simplified Solutions of Certain Mendelian Problems. ^85 



characters carried by three of these colours are already known, and, if we set 

 down the set of four with the three known combinations, we shall readily 

 infer the characters carried by the fourth group : — 



Agouti, 9X3^^ 



Dilute agouti, .... 3 



Black, . . . . ?, X Y Z 



Blue, . . . . . I X Y z. 



Since it is carried by more than half the groups in the set, Y must be 

 carried by all. The differentiating characters are therefore X and x and Z 

 and s, and, since three of the combinations they can form, namely XYZ, 

 xYZ, and xYz, are already appropriated, the remaining combination must 

 belong to dilute agouti, whose three characters are therefore XFz. 



In Miss Durham's final experiment cinnamon agouti and silver fawn 

 were mated, and their hybrids' progeny consisted of cinnamon agoutis, 

 dilute cinnamon agoutis, chocolates, and silver fawns in the ratio 9:3:3: 1. 

 If we again arrange these four groups in the usual order with the characters 

 of the three which are already known set down against them, we shall be 

 able to infer the characters carried by the fourth : — 



Cinnamon agouti, . . . . % X \j Z 

 Dilute cinnamon agouti, . . 3 



Chocolate, . . . . . '6 x y Z 



Silver fawn, . . . . . \ x ij z. 



Since it is common to three groups, y must also be carried by the fourth. 

 The differentiating characters in the set are therefore X and x and Z and z, 

 and, since three of the four possible combinations are already appropriated, 

 the remaining combination Xy% must belong to dilute cinnamon agouti. 



Thus the complete set of eight groups consists of — 



In parts of the country where tame rabbits have become feral, black 

 young are sometimes found in the nests of wild grey parents. Thus grey 



