Inheritaxce in Tomato Hybrids. 



15 



pigment, x\z. yellow. Two other apparently similar crosses 

 were made which ga\ T e very different results. This was between 

 the Beauty variety on the one hand and the Yellow Plum and 

 Yellow Cherry varieties on the other. The flesh of Beauty is a 

 deep purplish red or pink, and the skin is practically transparent. 

 The Yellow Plum and the Yellow Cherry varieties have both 

 yellow flesh and yellow skin for fruit. We are, therefore, deal- 

 ing with dihybrids in fruit color, the parents being different in 

 both flesh and skin color. 



The hybrids of the F t and F 2 generations, when brought to 

 maturity gave the results embodied in the following table: 



Crosses 



Fi Generation 



F 2 Generation 



Ratio 



No. 



Character 



Pink 



Red 



Yellow 



Yellow Plum X Beauty 



14 

 16 



Red fruit 

 Red fruit 



s 



14 



16 



4 

 4 





Yellow Cherry X Beauty 









Total 





10 1 30 



8 



1:3:4-5 







While apparently exceptional, these results are readily 

 understood when we comprehend the true nature of the crosses. 



The complete dominance of the pink flesh factor of the 

 Beauty parent and of the yellow skin factor of the other parents 

 gave plants bearing fruit with pink flesh and yellow skin which 

 produces red. Thus what might appear to be a temporary 

 blending of color is due to the phenomena of dominance and the 

 interaction of two distinct dominant and separably heritable 

 color factors. 



In the F 2 generation we find the original parental colors 

 and the F t hybrid color or intermediate type. These exist on 

 an average for both crosses in the proportion of 1 pink to 3 

 red (or intermediate) to 4-5 yellow. The number of reds is too 

 high for a simple and temporary blended monohybrid, but is in 

 harmony with the expected proportion for a dihybrid; which 

 is. 75 pink to 2.25 reds; 1 yellow or 3 pink, 9 red and 4 yellow. 



Yellow Pear x Honor Bright. 



The parents to this cross differ with respect to three attri- 

 butes — fruit color, fruit shape and foliage color. The Yellow 

 Pear variety is characterized by pyriform shape and yellow color 

 of fruit and green color of foliage; while the Honor Bright parent 



