MODERN PLANT-BREEDING METHODS 



709 



numbers of plants which have to be described as " inclined 

 to sport a little," a fact not unconnected in most cases with 

 the occurrence of heterozygotes. 



Numbers of cases, however, have now been observed where 

 thousands of individuals have been raised of fixtures isolated 

 in the first and second generations from the actual hybrids 

 without showing any signs of reversion to the parent types. 

 Such facts do away at once with the conception that the fixity 

 of a given type is dependent on the number of years for which 

 it has been cultivated. The inheritance of the following pairs 

 of characters has been shown to be on Mendelian lines : 



Dominant. 



Lack of awns (beardless). 

 Red colour in paleae and 



glumes. 

 Grey colour in paleae and 



glumes. 

 Grey colour in paleae and 



glumes. 

 Presence of hairs on glumes, 



or rough chaff. 

 Keeled glumes. 

 Red colour of grain. 



Wheat. 



Recessive. 

 Presence of awns (bearded). 

 White colour in paleae and 



glumes. 

 White colour in paleae and 



glumes. 

 Red colour in paleae and 



glumes. 

 Lack of hairs. 



Rounded base to glumes. 



White colour of grain. 



In the case of the following characters the heterozygote is 

 intermediate between the two parents : 



Long and short glumes. 

 Long and short grains. 

 Lax and dense ears. 

 Brittle and tough rachis. 



The various characters in the barleys have been investigated 

 with the following results : 



Dominant. 



Black colour in the paleae. 

 Purple colour in the paleae. 

 Colour in the grain. 

 Trifurcate paleae. 

 Lack of awns. 

 Brittleness of the rachis. 

 Narrow glumes. 



Recessive. 



White paleae. 



White paleae. 



White grain. 



Paleae ending in awns. 



Paleae ending in awns. 



Toughness of the rachis. 



Broad glumes. 



