306 heredity and environment 



Summary 



The principles of heredity established by 

 Mendel are almost as important for biology 

 as the atomic theory of D alt on is for chem- 

 istry. By means of these principles par- 

 ticular dissociations and recombinations of 

 characters can be made with almost the same 

 certainty as particular dissociations and recom- 

 binations of atoms can be made in chemical 

 reactions. By means of these principles the 

 hereditary constitution of organisms can be 

 analyzed and the real resemblances and differ- 

 ences of various organisms determined. By 

 means of these principles the once mysterious 

 and apparently capricious phenomena of pre- 

 potency, atavism and reversion find a satis- 

 factory explanation. 



Before the establishment of Mendel's prin- 

 ciples heredity was, as Balzac said, "a maze 

 in which science loses itself." Much still re- 

 mains to be discovered about inheritance, but 

 the principles of Mendel have served as an 

 Ariadne thread to guide science through this 

 maze of apparent contradictions and excep- 

 tions in which it was formerly lost. 



