132 THE THEORIES OF EVOLUTION 



in a certain direction and acquires a determined 

 character, it is because certain pangenes issue 

 from the nucleus, multiply in the cytoplasm and 

 impart to it a certain character. The nucleus al- 

 ways retains a complete series of pangenes, for 

 they always multiply before migrating out of it. 

 The pangenes only manifest their motor activity 

 during their migration from the nucleus into the cyto- 

 plasm — what De Vries calls intracellular pangenesis. 



Heredity is then easily explained. The nuclei of 

 all germ cells contain the pangenes of every char- 

 acter of the parents; as the characters found in the 

 offspring result from the cleavage and migration of 

 those pangenes, hereditary resemblance becomes in- 

 evitable. The inheritance of acquired characters re- 

 mains unaccountable, and justly so, for De Vries de- 

 nies it in toto. 



Variation may be due to the multiplication of pan- 

 genes. One single pangene can represent a charac- 

 ter but it cannot express it. In order to express a 

 character pangenes must multiply and the larger their 

 number the more deeply marked the corresponding 

 character will be. As their multiplication may be 

 quicker or slower it can become the source of many 

 individual variations. Besides slight individual varia- 

 tions, there are more important and durable varia- 

 tions from which an entirely new species may spring 

 up. These are the variations which De Vries desig- 



