CHAPTER IV 



THE INHERITANCE OF ACQUIRED 

 CHARACTERS 



1. SUMMARY OF PRECEDING CHAPTERS 



HEREDITARY resemblance is due to the derivation of 

 offspring from the same stock as the parent, and 

 successive generations, therefore, are simply periodic 

 expressions of the same continuous stream of germ- 

 plasm. 



Perfect inheritance, or uniformity of generations, 

 does not exist, since variations always occur in suc- 

 cessive generations. It is upon these variations that 

 evolution depends. Without them there would be no 

 change of type and consequently no possibility of 

 evolutionary advance. 



Some variations are fluctuating or continuous in 

 character and may be detected and analyzed by sta- 

 tistical methods, while others are mutations, or dis- 

 continuous variations, representing qualitative differ- 

 ences which do not lend themselves readily to statistical 

 analysis. 



Mutations are more common than was formerly 

 believed, and since they are germinal rather than 

 somatic in character, they play an important role in 

 heredity. 



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