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Reversional Heredity, or Atavism^ occurs when a child 

 resembles its grandparents or earlier ancestors, and is a very 

 influential law. The grandson very frequently resembles 

 his grandfather, and the grand- daughter her grandmother. 

 Lucas thus defines it : " Atavism is a term used to denote 

 cases in which a child, instead of resembling his immediate 

 parents, resembles one of his grandparents, or still remoter 

 ancestor, or even some distant member of a collateral 

 branch of the family a circumstance which must be 

 attributed to the descent of all its members from a common 

 ancestor." It is also referred to by Aristotle, Galen, and 

 -Pliny. Montaigne says : " Is it not marvellous that this 

 drop of seed from which we are produced should bear the 

 impression not only of the bodily form, but even of the 

 thoughts and inclinations of our fathers ? Where does this 

 drop of water keep this infinite number of forms? And 

 how does it bear these likenesses through a process so hap- 

 hazard and so irregular that the great-grandson shall resemble 

 the great-grandfather, the nephew the uncle ?" Atavism has 

 shown itself in the silk-worm after a hundred generations, 

 and is beautifully exemplified in the vegetable kingdom, as 

 shown by Dr. Broca. Reversional heredity is often mani- 

 fested in insanity. Thus, an insane father may have clever 

 and distinguished sons, probably geniuses, yet the offspring 

 of these may manifest insanity at any time, even suddenly. 

 Character, talents, aptitudes, and passions, afford many 

 striking examples of atavism. 



Indirect Heredity is in reality only a modification of 



atavism, differing from it only in appearance. It occurs 



r when a child resembles in its physical, mental, and moral 



I character, an uncle or aunt, or some other relative out of 



the direct line of descent. Some have denied that this 



