GENERAL RELATIONS IN INHERITANCE 299 



very great variety of gene combinations — not particularly 

 excellent, nor particularly defective. A large majority of the 

 members of the two extreme classes arise from parents of 

 the mediocre class. When from such parents fortunate com- 

 binations are made, the genes supplementing each other, 

 offspring are formed that pass into the superior class. In 

 man these are the Inventors, the writers, the men of science, 

 the poets, the captains of industry. When a bad combina- 

 tion is made, the children fall back into the undesirable class : 

 the vagabonds, criminals, paupers, ne'er-do-wells. A new 

 combination is made with every child, and any single pair 

 of parents can form literally thousands of diverse combina- 

 tions. So from the same parents some of the children may fall 

 in the superior group, some in the mediocre group, some in 

 the inferior group. From the great mediocre group arise 

 more of the superior group than from the superior group 

 itself, and from it, too, arise more of the inferior group than 

 from the inferior group itself. The superior group are like 

 the cream which arises slowly from the interior of a vessel 

 of milk. And the inferior group are the settlings, the poor 

 genes that get together and sink to the bottom. 



In all this variation resulting from the formation of new 

 combinations of genes, it is of course true that there is in 

 the long run and on the average a tendency for the offspring 

 of given parents to resemble their parents more than they 

 do other individuals, because parents and offspring have 

 more genes in common than have unrelated Individuals. For 

 the same reason the members of a given family resemble 

 each other more than do unrelated Individuals. This is illus- 

 trated by considering the situation with respect to one pair 

 of genes, as A and a. From dominant parents AA or Aa 

 come a larger proportion of dominant than of recessive off- 

 spring. From recessive parents aa come only recessive off- 

 spring. Similar but less sharply defined relations hold when 

 we consider parents differing In many genes; there is a cer- 



