INHERITANCE— IMPROVEMENT BY BREEDING 161 



enable us to "fix" a new type when we get it. "Choose CHAP, 

 your parents" is the axiom of the successful breeder. It is v - 

 true that considerable success has in the past been achieved 

 by empirical mating ; but it does not advance the farmer far, 

 and at best it is but a slow, risky, and expensive means of 

 attaining the desired end. 



The fact that maize is the basis of the agricultural wealth 

 of a large country makes it eminently desirable that every fact 

 about the inheritance of its characters should be learned as 

 soon as possible. " It is only through the application of such 

 knowledge that the present arbitrary and, in a way, unscientific 

 methods of its improvement as an economic crop will be placed 

 upon a definite and orderly basis" {East and Hayes, I ). 



Certain phases of the question of inheritance are of definite 

 practical agricultural interest, as, for instance, the possibility 

 of increasing the yield of a farm crop. Other phases which 

 are the subject of investigation by students of genetics may 

 seem, on the surface, to be of less importance, or to have no 

 bearing at all on practical problems. But it should be borne 

 in mind that all problems in genetics, even though they appear 

 to be of scientific interest solely, bring us nearer to the com- 

 plete understanding of the transmission of those characters in 

 our live stock as well as in our various crops, which are of 

 definite importance from the financial point of view. 



122. Inheritance of Characters in Maize folloius Mendelian 

 Law. — Different students and writers have shown from time 

 to time that the maize plant behaves in accordance with Mendel 's 

 laws of the inheritance of characters. As the result of extended 

 investigation by East and Hayes (i), these authors conclude 

 that in the behaviour of the maize plant there is no conclusive 

 evidence of (i) failure of segregation of the male gametes ; (2) 

 selective fertilization ; and (3) partial gametic coupling; and 

 that aberrant ratios such as have occasionally been reported 

 (e.g. Correns, 3) may be due to modification by other unknown 

 characters possessed by the parents. 



" When Mendel's Law of Heredity was rediscovered in 

 1900, it was the general belief that it covered only a few 

 isolated cases. Many apparent exceptions were cited. One 

 by one, however, these exceptions have been found to yield 

 to interpretation by simple extensions of the Mendelian nota- 



