INHERITANCE— IMPROVEMENT BY BREEDING 197 



in vigour due to crossing was noticeable, such as was met CHAP, 

 with by East and Hayes. The same result was obtained with 

 the reciprocal cross, showing that in this case the short habit 

 is dominant. 



154. Inheritance of Abnormal Divarfness. — Abnormally 

 dwarf forms, i-i to 3 feet high, sometimes appear, possibly as 

 examples of " reversion " or of " mutation ". East and Hayes 



Fig. 82B. — Fj plant progeny of cross between types shown in Fig. 81 

 plants 4J to 5 feet high. 



find that segregation takes place in their inheritance, in the 

 proportion of three normal to less than one abnormal, but the 

 number of cases studied was perhaps inadequate to determine 

 whether it was a case of Mendelian dominance. 



155. Inheritance of Length of Ears. — Ear length does not 

 show the increased vigour, according to East and Hayes, due 

 to heterozygosis, that is seen in the heights of the plants. 

 They conclude that there is scarcely a doubt that the greatly 



