matter of the genetic relation between successive genera- 

 tions is most complex, comprising, as it does, the considera- 

 tion of many factors as yet but partially recognised and 

 understood; however, much progress has been made in the 

 study of heredity since Darwin's day, and several import- 

 ant laws have been discovered so that order is takmg the 

 place of chaos in some fields of inquiry. 



From the standpoint also of the practical breeder of 

 animals and plants a knowledge of the laws of heredity 

 would be of great importance. The production of improved 

 forms of our domestic animals and cultivated plants would 

 be tremendously accelerated, and a corresponding increase 

 in value of animal and plant productions would take place. 



Many proverbs and phrases are current which show 

 that the "common man" emphasizes the importance of 

 heredity and environment. Some of these are " Like father, 

 like son;" "Get a cat of a good kind;" "The fathers have 

 eaten sour grapes, the children's teeth are set on edge;" 

 "The corncrib cross;" "The breed goes in at the mouth;" 

 "You cannot make a silk purse of a sow's ear;" One can- 

 not gather grapes from thorns nor figs from thistles;" 

 "The child is a chip of the old block;" "Wooden legs are 

 not heritable, but wooden heads are;" "What's bred in the 

 bone;" "Blood tells;" "Every good tree bringeth forth 

 good fruit, but a corrupt tree bringeth forth evil fruit." 



Methods of Investigating Heredity 



Three lines of research have been conducted by stu- 

 dents of heredity: (1) by studies of statistics of the progeny 

 of crossing strains of plants and animals, after the manner 

 of Galton and Pearson: the Statistical Method; (2) by ex- 

 perimentation after the manner of Mendel and his followers: 

 the Mendelian Method; and (3) by the microscopic study of 

 the germ cells and the behavior of the contained chromo- 

 somes, after the manner of Weismann and his followers: 

 the Biologic Method. 



(a)— The Statistical Study of Heredity 



The statistical method of study of problems in heredity 

 was first applied by Francis Galton. Later, important 

 additions were made by Pearson and his associates, so that 

 there is now a large number of reports based on statistical 

 studies of various phases of evolution. The new science is 

 called Biometry or Biometrics. 



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