468 Kepokt of the Depart.meat of Horticultuhk ok the 



leading varieties, the knowledge should be of value for either 

 identical or other crosses. From a study of all the material, we 

 may hazard the following provisional statements: 



First, the fruits in which yellow predominates over red are 

 in a heterozygous condition for yellow and red ; second, the fruits 

 in which red predominates are either homozygous or heterozy- 

 gous; third, the pure yellows are recessive and consequently are 

 homozygous. These conclusions are drawn from the following 

 data. 



In (the Ben Davis X Jonathan progeny,^ we have eleven seed- 

 lings, all red or nearly red. The yellow portion of these apples 

 is so meager as not to arouse suspicion of a heterozygous con- 

 dition. The assumption that there is no yellow in Ben Davis or 

 Jonathan is supported by the results in other crosses in which 

 one of these varieties was a parent. If, however, red consists of 

 a complex of unit characters — the very light red being the 

 simple unit character and the dark red a multiple of red unit 

 characters, then, of course, it is impossible to tell from these few 

 individuals wdiether yellow is or is not a recessive in this cross. 

 For example, red would have to consist of only three unit char- 

 acters to require sixty-four individuals to give one yellow. It 

 would not be surprising if the red color in apples consists of 

 more than one unit for red, since in other plants color is often 

 composed of more than one unit character. Thus, Xillson-Ehle^ 

 separated two distinct blacks in his study of the inheritance of 

 black color in the glumes of oats, and three distinct, inheritable 

 reds in a red Swedish wheat. East^ found two yellow colors 

 in the endosperm of yellow corn, " each behaving when crossed 

 with its absence, as an independent allelomorphic pair." If one 

 yellow in corn gives a light yellow appearance, it is not unrea- 

 sonable to expect that one red in apples may give a very light 

 red and a complex of red unit factors a dark red. The only 

 method of determining this point is, of course, by segregating 

 the unit factors in future generations. 



1 The first name in all cases is the maternal parent and the second the 

 paternal. 



2 Xillson-Ehle, H., 1909, " Kreuzungsunterbuchungen an Hafer und Wei- 

 zen," Lunds Universitets Arsskrigt, N. F. ; Afd. 2, Bd. 5, Nr 2, 1-122. 



3 East, E. M., 1910. "A JNlondclian Interpretation of Variation that is Ap- 

 parently Continuous ", Am. Nat. 44: 65-82. 



