METHODS OF INVESTIGATING HEREDITY 537 



depends upon his knowledge of the laws governing their opera- 

 tions. Through our knowledge of the laws of electricity we are 

 now able to utilize it in furnishing light, running motorS; and in 

 many other ways. Also a knowledge of the laws governing 

 nature's forces enables us to so guide our actions as to escape 

 disasters that might otherwise befall us. Through a knowledge 

 of the laws of electricity we are able to protect om- buildings and 

 ourselves from lightning. To the discovery of the laws governing 

 diseases we attribute most of the improvement in public health. 

 So it is with heredity, that force of nature whereby the individ- 

 uals of each generation of plants and animals have their struc- 

 tures and functions largely determined by their ancestors. 

 Heredity is one of the most important facts pertaining to Hfe. 

 It is a fundamental fact to be considered in attempting to produce 

 better plants, better livestock, and better human beings. In 

 eliminating diseases and all undesirable qualities of plants and 

 animals, even including insanity, criminality, and many of the 

 diseases of the human race, heredity must be considered. It is 

 not strange that students of heredity are so eager to discover its 

 laws, for thereby they can predict from a study of previous 

 generations what the individuals of future generations will be, 

 so control the breeding of plants and animals as to produce at 

 will more desirable types and eliminate undesirable ones, and 

 also offer suggestions to the human race whereby many of our 

 evils and ills can be eliminated. 



Methods of investigating Heredity. — Much work has been 

 done on heredity that has contributed very little to our knowl- 

 edge of the subject. The results obtained in investigating a 

 problem depend upon how the problem is attacked and the 

 method of procedure during the investigation. 



Some investigators of heredity employ the statistical method. 

 By this method large groups of plants or animals are studied 

 instead of separate individuals. Such investigators are known 

 as Biometricians. They determine how masses or populations of 

 individuals behave throughout generations in respect to heredity. 

 They deal with averages. For example, they determine whether 

 or not the average yield, height, or aver weight of a mass of 

 individuals is remaining constant. Such information often has 

 considerable value. For example, by keeping a record of the 

 average yield per acre of different strains of Wheat, the strain 



