Halsted: Colors in Vegetable Fruits 



19 



result will be according to rule, namely, 

 all plants bearing pinlc fruits for Fi, and 

 three-fourths of the plants bearing pink, 

 and one-fourth plants bearing lemon 

 colored fruits in the F2. When bred 

 with the second group, namely, the 

 orange-fruited sorts, the combination is 

 between the colorless skin and pink 

 flesh of one parent with the orange skin 

 and lemon flesh of the other, and there- 

 fore both pairs of characters are present. 

 In the Fi the two dominants assert 

 themselves and all plants produce red 

 fruits, that is, neither parent color is 

 reproduced ; while in the F2 all four of the 

 above named types are obtained in the 

 following ratios: red 9, pink 3, orange 

 3, lemon 1. 



The following table may help to add 

 clearness to the above conclusions by 

 graphically showing the details of the 

 combinations : 



is, contain nothing that is unexpressed, 

 and these occupy diagonal squares from 

 the upper left to the lower right hand 

 corner. Plants that arise from these 

 unions, if grown in strict isolation, re- 

 produce themselves and through their 

 progeny for all time either red, pink, or- 

 ange or lemon fruits as the case may be. 



SECOND GENERATION COMBINATIONS 



The diagrammatic table is introduced 

 in particular to show in how many ways 

 the four characters are combined in the 

 F2 of the cross that is here considered. 

 It is seen that the following unions are 

 expected: P. O. 1(2), P. 0. c(2), P. O. 

 1 c(4)_, P. l._ c(2), O. 1. c(2); that is, 

 there is one in eight of the plants with 

 red fruits that carries the factor for 

 lemon flesh, and an equal number of red 

 fruited plants with the colorless skin 

 factor recessive. For example, when a 



Table I 



In Table I the upper row shows the 

 possible combinations of the factors as 

 found in the pollen grains, the capital 

 letters standing for dominant factors, 

 while the recessive are represented by 

 small letters. The same set of asso- 

 ciated factors for the ovules is shown in 

 the first vertical column on the left. 

 The other sixteen rectangles express the 

 unions that may be made between the 

 pollen grain diagramed above with the 

 ovule given at its extreme left. 



Among the sixteen possible combina- 

 tions there are four that are pure, that 



P. O. 1. plant is bred to itself or its equal 

 there will result one pure P. O. and one 

 pure P. 1. plant to every two of P. O. 1. 

 plants and therefore, unless isolation is 

 practiced, there will be a perpetual 

 mixture of red and pink-fruited plants. 

 There is also one plant in every four 

 of the whole block with red fruits that 

 has both recessive characters present, 

 and in the next generation will show all 

 the four sets of combinations that are 

 here being considered. Then there is 

 one in eight of all the plants with pink 

 fruits that is carrying the factor for 



