ORIGIN AND IMPROVEMENT OF FRUIT 331 



ern Spy; and Sutton and Northern Spy. Some of the im- 

 portant observations by the authors as a result of the work 

 are as follows: (1) These crosses strikingly contradict the 

 idea that seedling apples (of cultivated sorts) revert to the 

 wild prototype. (2) The stimulus of hybridity is very 

 marked in the vigor of the crosses under consideration. 

 (3) The behavior of some of the crosses strongly suggests 

 that apples may be "preponent" in one or more of their 

 characters. 



Other conclusions which bear on the laws of inheritance 

 are: 



In color of skin, the fruits in which yellow predominates 

 over red seem from the data to be in a heterozygous condition 

 for yellow and red. The fruits in which red predominates 

 are either homozygous or heterozygous. The pure yellows 

 are homozygous. 



The data favor the supposition that so far as size and 

 shape are concerned, these characters are inherited practically 

 as intermediates. 



While all the varieties were sub-acid, the progeny indicate 

 strongly that crosses of these sub-acid varieties break up in 

 the proportion of three sour apples to one sweet one. 



292. The heterozygous nature of fruits. — If an individual 

 plant is pure or homozygous for any one or all of its charac- 

 ters, then all of the sexual gametes produced by it would, if 

 the plant is self -fertilized, produce progeny which are alike. 

 Thus, if a Grimes Golden apple were homozygous for all 

 of its characters when self-fertilized, all the seedling trees 

 produced would be practically identical with the parent. 

 Such a condition does not exist, however, for the seeds of a 

 self-fertilized apple tree will produce a motley array of prog- 

 eny, varjing in color, form, quality, and tree characters. 

 Therefore, all of the common varieties are heterozygous and 

 may be regarded as the Fi generation of previous crosses. 



