266 HEREDITY AND ENVIRONMENT 



nized more than twenty different factors for 

 the color and form of flowers in the snap- 

 dragon, Antirrhinum. 



These factors are probably complex chemi- 

 cal substances which preserve their individu- 

 ality in various combinations, just as groups 

 of atoms or radicals do in chemical reactions; 

 they may be dropped out or added, substituted 

 or transposed, just as chemical radicals may 

 be in chemical compounds. To this extent 

 they maintain continuity and independence, 

 but they are not absolutely independent for 

 they react upon one another as well as to en- 

 vironmental changes, so that the characters of 

 the developed organism are the resultants of all 

 these reactions and interactions. 



Inheritance Factors and Germinal Units 



If it is asked whether there are particular 

 structures in germ cells which correspond to 

 particular inheritance factors it must be ad- 

 mitted that we have no certain knowledge on 

 this subject and that opinions differ greatly 

 with respect to it. On the one hand it is 

 maintained that the entire germ is concerned 



