HEREDITY 165 



are also inherited, but in much Jess certainty of degree. These 

 traits belonging to a member of a single generation have a 

 smaller "inheritance fund" on which to draw. In each gener- 

 ation some of these individual qualities are latent or "reces- 

 sive," others are potent or "dominant." The recessive or an- 

 cestral characters reappear with a certain regularity. They 

 may form a sort of mosaic, by mixing with other dominant 

 traits, or they may make a more or less perfect blend. Resem- 

 blance to some remote ancestor occurs at times, being known as 

 atavism. Each ancestor has some claim in the formation of the 

 new individual, and behind the grandfather and grandmother 

 dead hands from older graves reach in their direction. The past 

 will never let go, though with each generation there is a deeper 

 crust over it. These old claims grow less with time, because 

 with each new generation there are twice as many of these com- 

 petitors. ^Moreover past generations can afTect the heredity 

 of the individual only through the agency of his immediate 

 parents. Out of these elements Mr. Galton frames the idea of a 

 " mid-parent," a sort of center of gravity of heredity, though, as 

 Dr. Brooks has observed, it is doubtful if this mid-parent is 

 more than a logical abstraction. The bluer the blood in any 

 species, that is, the more closely alike the ancestors are, the 

 more certain will be the personal resemblance among the de- 

 scendants. 



But characters actually latent are very real in heredity. 

 Dr. Brooks says : 



"When a son of a beardless boy grows up and acquires a heard, we 

 may say that he has inherited his grandfather's beard, but this is only 

 a figure of speech, and he actually inherits the beard his father miglit 

 have acquired, had he lived, nor would the case of a child descended 

 from a series of ten or a hundred beardless boys be different." 



It is, moreover, certainly true that a beard can be as well 

 inherited from the mother — who has none — as from the father. 

 The inheritance is that of the beard the mother might have 

 developed had she been a man. And, in general, in matters of 

 heredity, the child is not derived from the parents as they 

 actually are, but from tlie parents as they might liave been. 

 The traits transmitted in heredity are chosen from the whoh' hue 

 of parental possibilities. And with the process of conception, 

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