54 HEREDITY AND EVOLUTION IN PLANTS 



past, no one knows how far. How will these two inheri- 

 tances affect each other when they intermingle in the 

 fertilized egg? Will one tend to inhibit or check certain 

 characteristics or functions of the other; will they evenly 

 blend, so as to produce an expression intermediate between 

 that of the parents; or may entirely new substances be 

 formed or new combinations take place, resulting in an en- 

 tirely new expression in the offspring? 



42. Methods of Study. To endeavor to answer the 

 questions just asked is as fascinating an occupation as it is 

 important, and the answers are significant for man, as well 

 as for plants. It is indeed, a fortunate thing that prin- 

 ciples ascertained by studying plants apply equally to man 

 and other animals, since plants are so much easier to 

 handle in experimental investigations. 



We may go about the answering of these questions in 

 either of two ways. We may gather large numbers of 

 statistics to measure and analyze (statistical or biometrical 

 method), or we may employ the experimental method. The 

 method of biometry enables us to deal with a larger number 

 of individuals, but the material studied is usually a mixed 

 population, whose history is only imperfectly known, the 

 conditions are more complex, and little if at all under 

 control. By the experimental method it is not necessary 

 to deal with such large numbers ; we may choose carefully 

 pedigreed material, about the history of which we have 

 more or less accurate knowledge, and we may greatly 

 simplify and control the conditions under which we make 

 our observations. The largest advance toward the solu- 

 tion of the problems of inheritance has been made by the 

 experimental method, in the form first employed success- 

 fully by Gregor Mendel. This method will be briefly 

 explained in the next chapter. 



