CHAPTER IV 

 SOME LAWS OF HEREDITY 



Some of the phenomena of heredity are so 

 conspicuous that they are evident to everyone; 

 yet they are so commonplace that we pass 

 them by without appreciating their significance. 

 That hke reproduces like is a fundamental con- 

 ception in practice as well as in theory. The 

 hen is set on a clutch of her eggs with every 

 assurance that chickens will hatch. Men do 

 not "gather figs of thistles," and that which 

 is sown we expect to reap. It is furthermore 

 well known that particular traits or features 

 may appear as family characteristics. In one 

 of the royal families of Europe, the Hapsburg 

 family, a prominent jaw and full lips were so 

 marked that "the Hapsburg jaw" was almost 

 a mark of royalty. Such traits or features may 

 occasionally skip a generation to reappear in 

 some later member of the family. The child 

 may resemble a grandparent or an uncle. 



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