84 WHAT EVOLUTION IS 



assumption of the inheritance of ac- 

 quired characters. Acquired charac- 

 ters are those pecuHarities that are 

 gained during the Hfetime of an in- 

 dividual as contrasted with his inborn 

 traits. That Lamarckism shall be 

 effective, it is necessary that precisely 

 these characters be inherited. For a 

 long time biologists have attempted 

 to show that such characters are in- 

 herited, but thus far they have been 

 unable to get any conclusive evidence 

 that such is the case. 



The chief opponent of the inherit- 

 ance of acquired characters was 

 Weismann (1834-1914) who pointed 

 out that the bodies of the higher ani- 

 mals were composed of two catego- 

 ries of cells, the body cells proper 

 such as muscle cells, nerve cells, skin 

 cells, and the like, and the reproduc- 

 tive cells, the egg cells and sperm 

 cells. He also showed that acquired 



