No. 611] LINKED CHARACTERS IN WHEAT CROSSES 

 TABLE V 



Eatio W./T. of Head and Average Percentage of Hard Ge 



In* the opposite direction, i. e., races which markedly 

 violated the correlation by having very high ratios (1.50 

 or more) but with low percentages of hard grains did not 

 occur. 



Again it may be objected that an explanation of this 

 correlation between shape of head and texture of grain 

 as a genetic linkage, is incorrect because the linkage is 

 not complete, i. e., there is considerable regression. This 

 objection may be fully met by the observation that both 

 of the characters here concerned are quantitative and 

 hence subject to fluctuation around a mean. Moreover, it 

 is almost certain that both characters are genetically com- 

 pound, i. e., each are the result of more than one factor, 

 recombinations of which may markedly vary the quanti- 

 tative visible expression of the characters. If, therefore, 

 but a single factor for grain texture be linked with one of 

 the factors concerned in the shaping of the head, there 

 will result a partial correlation of these two characters 

 such as we find. 



The data here presented, therefore, seems to indicate 

 that the two characters, hardness of grain and high ratio 

 of width to thickness of head, which entered this cross 

 together in the macaroni parent, tend to come out together 

 in the segregates of the and F.^ generations, ?". e., that 

 there is a genetic linkage between one or more of the 

 factors controlling the grain texture and head shape in 

 the two varieties employed as parents. 



