548 STRUCTURE AND LIFE HISTORIES 



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. 



