CHAP. 



INHERITANCE— IM PRO VEMENT B V BREEDING i 7 3 



Dominant: Recessive: 



starchy grain becomes trans- V 



lucent and horn - coloured or 

 creamy. 



Development of "pods" around Nakedness of grain, 

 the grain. 



Red colour of cob. Absence of red, i.e. white. 



Red silk. Greenish white silks with or with- 



out red hairs, and white silks. 



Red pericarp.' Colourless pericarp. 



Green leaves. "White" leaves, i.e. absence of 



chlorophyll. In this case the 

 heterozygous plants have striped 

 leaves. 1 



Tendency of the ear to split at the Normal type of ear. 

 base into 2-rowed sections. 



Fasciation of the ear. Normal shape of ear. 



Presence of ligule and auricles. Absence of ligule and auricles. 



131. Interaction of Unit-characters. — In some cases we find 

 that a dominant character is present, although it does not 

 appear; to such cases the term "imperfect dominance" has 

 sometimes been given, because it has been thought that they 

 were cases in which the so-called " Law of Dominance " did 

 not apply. It has been found, however, in several instances 

 that the failure of the dominant character to appear is due to 

 the absence or presence of some other factor on which its 

 appearance or non-appearance depends. The phenomenon is 

 known to occur in sweet-peas and other plants, and also 

 among animals. 



The character of flintness is present in some breeds of 

 sugar-maize, but is unable to appear owing to the absence of 

 white starch in the endosperm. In some breeds of maize two 

 kinds of yellow colour are present in the endosperm ; one of 

 these depends for its appearance on the presence of a factor 

 (C) for colour, though what this factor is, is not yet known ; 

 the result in this case is that by crossing two whites we obtain 

 a yellow if each of the parents carries one of the requisite 

 factors ; this has sometimes led to the supposition that a 

 dominant white was present (i.e., that the yellow colour was 

 recessive). That this is not really the case is demonstrable, 

 for by adding the factor for colour the two together are domi- 

 nant over white. 



1 East and Hayes observe that several races exist in which the striping is 

 apparently homozygous and the race breeds true. 



