THE METHOD 101 



other, which he called recessive. The second gener- 

 ation produced from the cross bred plants, which were 

 allowed to fertilize themselves, instead of being uni- 

 form, like their parents, broke into two original forms, 

 in the average ratio of three dominants, to one reces- 

 sive. The recessives are pure, and if allowed to fer- 

 tilize themselves give rise to recessives only, for many 

 generations. One-third of the dominants are also pure, 

 while the other two-thirds produced descendants of 

 which two-thirds are dominants, and one-third piire 

 recessives. Each successive generation consists of 

 dominants and recessives in the ratio, for each one 

 hundred, of twenty-five dominants of pure blood, 

 twenty-five recessives of pure blood, and fifty domin- 

 ants, which produced descendants in the ratio of three 

 dominants to one recessive." 



Mendel reduced this principle to a mathematical 

 formula. For a long time naturalists paid little at- 

 tention to this law. But a few years ago it was re- 

 vived by Bateson and De Yries. 



The latest expression upon this law came from a 

 practical breeder, Prof. Webber of Cornell University. 

 He says : "No discovery in the field of breeding has had 

 more effect, or is more far reaching, in its importance, 

 than the discovery of what have now become to be 

 knoAvn as Mendel's principles of heredity. 

 The law of segregation has shown us, that the splitting 

 of characters follows a definite method, and that we can 

 in general estimate the frequency of occurrence of a 

 certain desired combination, if we know the characters 

 concerned, to be simple unit characters. * * * We 

 can now study the characters presented by the differ- 

 ent varieties of a plant, or of different species, which 

 can be crossed with it, and definitely plan the com- 



